Contact Us Now
Facebook-f Twitter Linkedin-in Instagram Pinterest
Accent Controls (P) Ltd logo
Get Consultation

(+91) 9867364004

Author: admin

Level Sensor Manufacturers in India: Choosing a Tank Level Switch

Most tank level problems in India are point level, not continuous measurement — and for a non-metallic tank, a capacitive switch on the outside wall solves it with nothing wetted at all.

Most level enquiries that reach us do not actually need level measurement. They need to know when a tank is full, or when it is empty, so that a pump starts or stops or an alarm sounds. That is point level detection, and it is a much simpler and cheaper problem than continuous measurement.

Establishing which one you have is the first decision, because it changes everything that follows.

Point level or continuous?

Point level — a switch. Output changes at one defined height. Covers pump control, overflow prevention, dry-run protection, high and low alarms. This is the large majority of industrial requirements.

Continuous — a transmitter. Reports the level as a value across the range. Needed for inventory management, batching by volume, and closed-loop level control. Considerably more expensive.

Two or three point switches at the heights you care about frequently do the job that someone specified a continuous transmitter for, at a fraction of the cost and with far less to go wrong.

The wall material decides the technology

For point level in a tank, the single most useful question is what the tank is made of.

Non-metallic tank: capacitive, mounted externally

This is the one people are surprised by, and it is genuinely the best answer for a large class of applications.

A capacitive proximity switch mounted on the outside of a plastic, fibreglass or glass tank can detect the liquid inside through the wall. Set the sensitivity so the empty wall does not trigger it but wall plus liquid does, and you have a level switch with:

  • No penetration of the tank
  • No seal that can leak
  • Nothing wetted, so nothing to clean and nothing to corrode
  • No mechanical part inside to jam
  • Free repositioning — move the bracket, change the switching height

For water tanks, chemical dosing tanks, plastic storage tanks and fibreglass vessels this is frequently the correct and cheapest solution. Our D32C range is M30 with 10 mm sensing, in NPN and PNP, normally open and normally closed.

The caveat, which matters. The wall consumes part of the sensing range, so thick walls may be beyond it. And if product clings to the inside of the wall, the sensor reads full permanently. Thin water-like liquids are ideal; heavy clinging syrups and slurries frequently are not. Assess this before ordering — see capacitive sensors for level detection.

Metal tank: the sensor has to be inside, or use a float

A metal wall blocks capacitive sensing entirely. Two routes remain.

A fitting through the wall, with the sensing element inside. Effective, but now you have a penetration and a seal, and the element is exposed to the process.

A magnetic float with an external sensor. A float carrying a magnet rides on the liquid inside a non-ferrous stilling tube or chamber, and a magnetic proximity switch outside detects it. Magnetic fields pass through stainless steel and aluminium, so this works where capacitive sensing cannot. Nothing electrical is inside the vessel.

For stainless steel process vessels and hygienic applications this is often the right approach.

What the liquid is doing matters

Four properties that change the answer:

Conductivity and dielectric constant. Water and aqueous solutions are detected easily by capacitive sensing. Oils and solvents have lower dielectric constants and are harder — possible, but the margin is smaller and setup is more critical.

Coating behaviour. Anything that clings to the wall or to a probe is the main enemy of level sensing generally. If the product coats, design around it.

Foam. Foam has a dielectric between air and liquid and can trigger a capacitive sensor. Where foaming is expected, either mount in a stilling arrangement or choose a technology that ignores it.

Turbulence. A sensor at a fill point sees splashing and chatters. Mount away from inlets, or add hysteresis in the control logic.

Powders and granulates

Capacitive sensing works for solids too, and hopper level, silo high and low level, and blocked chute detection are common applications. Two differences from liquids: solids have lower dielectric constants than water so detection is less strong, and solids do not self-level — material can bridge above a sensor and leave it reading empty when the hopper is not.

Mount where material actually flows, not in a corner where it can arch over.

What we supply, and what we do not

Being direct, because the search term that brings people here is broad. We manufacture capacitive and magnetic proximity switches in Mumbai and supply them for point level detection. That covers most industrial tank and hopper switching requirements in India.

We do not manufacture continuous level transmitters — radar, ultrasonic or guided wave. If your application genuinely needs continuous measurement across the full range, that is a different product category and we would rather tell you than sell you three point switches and call it level measurement.

What is worth checking first is whether you actually need continuous measurement. A great many specifications call for it out of habit when two point switches would control the pump perfectly well.

Specifying a level switch

  • Tank material and wall thickness
  • The liquid or solid, and whether it coats, foams or is abrasive
  • Switching heights required, and how many
  • Whether anything may be inside the tank, or whether it must be entirely external
  • Temperature and pressure
  • Cleaning regime, if any
  • Output required and what it controls

A sketch of the tank with the switching heights marked answers most of this at once.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Sensors for Export Machinery: CE, IEC 60947-5-2 and the Documents Buyers Ask For

An Indian machine builder exporting to Europe carries the compliance burden for every component inside the machine. What to collect from your sensor supplier, and when to collect it.

An Indian OEM exporting machinery to Europe, the Gulf or North America takes on responsibility for the compliance of everything inside the machine. The sensors are a small part of that, but they are a part that causes disproportionate trouble — usually because the paperwork was not collected at purchase and cannot easily be obtained afterwards.

This is what to collect, and when.

IEC 60947-5-2: what it actually covers

IEC 60947-5-2 is the international standard for proximity switches. It is not a safety approval and not a certification mark — it is the specification that makes one manufacturer figures comparable with another.

Among other things it defines:

  • The standard target against which sensing distance is measured — material, dimensions and shape. Without this, a sensing distance figure means nothing.
  • Rated, effective and assured operating distance, and the tolerances between them. These are three different numbers and the gap between them is where field failures live.
  • Switching frequency and how it is measured.
  • Electrical requirements — supply range, residual current, voltage drop, short-circuit behaviour.
  • Marking and documentation requirements.

Accent manufactures to IEC 60947-5-2. The practical value for an exporter is that the figures on the datasheet mean the same thing an inspector expects them to mean, and that a design calculation done against them will stand up.

What to collect, and when

The timing matters more than the list. Collect at purchase, because obtaining documents for a component bought eighteen months ago is difficult and occasionally impossible.

  1. Declaration of conformity. The manufacturer statement of which directives and standards the product meets. Required for the machine technical file.
  2. The datasheet for the exact variant, not the series. Ratings differ between variants and an inspector will check the one you actually fitted.
  3. Material declarations where relevant — RoHS and REACH for European destinations, food-contact declarations for food machinery.
  4. Hazardous area certificates if any part of the machine is classified. See specifying intrinsically safe NAMUR loops.
  5. Traceability records if your quality system or your customer requires component traceability to a batch.

CE marking and where the responsibility sits

Worth being precise, because it is widely misunderstood.

You CE mark the machine. The sensor manufacturer does not CE mark the machine, and a CE-marked sensor does not make your machine compliant. What component documentation does is support your technical file — it lets you demonstrate that the parts you selected are suitable for the use you put them to.

A sensor supplier who claims their CE mark covers your machine has misunderstood the framework. A supplier who provides clear documentation so you can build your own file is being useful.

Where sensor choice touches machine safety

If a sensor performs a safety function — guard interlock, safe position, emergency stop related — then the relevant standards are the machinery safety ones, and an ordinary proximity switch is generally not sufficient on its own.

Two things to get right regardless:

Fail-safe direction. Specify normally closed for guard and interlock positions, so that a cut cable, a disconnected plug or a failed sensor produces the same signal as an open guard. With normally open, a severed cable is indistinguishable from a closed guard, and the machine keeps running.

Diagnostic coverage. Where the control system must detect a failed sensor rather than merely respond to it, a conventional three-wire sensor cannot help — its off state and a broken wire look identical. NAMUR sensing provides genuine line fault detection, which is one reason it appears on machinery well outside hazardous areas.

Practical points for exporters

Voltage and frequency at destination. A machine going to a 110 V, 60 Hz market needs components rated for it. This catches out AC two-wire sensors in particular — see the A20C range.

Connector conventions. M12 connectors are effectively universal in European machine building. A hard-wired sensor where the customer expects a connector is a small irritation that reflects on the whole machine.

Spares availability at destination. Your customer will ask how they obtain a replacement. Being able to answer properly is part of the sale, and it is worth establishing before the machine ships rather than when the first one fails.

Marking legibility. Part numbers must still be readable after commissioning. A sensor whose label is destroyed by the first clean-down creates a support problem for the life of the machine.

Why domestic sourcing helps here

Three reasons specific to exporters.

Documentation comes from the manufacturer directly, in the timeframe you need it, rather than through an import chain that may not have it.

Variants are available. Destination-specific voltage, connector type and cable length can be specified rather than accepted, which removes adaptation work from every machine you ship.

The part stays available for the service life of the machine. An imported range that gets rationalised leaves your customer — and your reputation — without a replacement.

Accent manufactures in Mumbai to IEC 60947-5-2 and has done since 1985. Tell us the destination market and the documentation your customer requires, and we will confirm what comes with the delivery before you order rather than after.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Magnetic Proximity Switches: Sensing Through Walls and Stainless Steel

A magnetic switch detects its target through a stainless steel wall. That single property solves sealing problems no other sensing technology can, and it is why they survive where everything else fails.

An inductive sensor stops at the first piece of metal. A photoelectric sensor stops at the first opaque object. A magnetic proximity switch does neither — it responds to a magnetic field, and a magnetic field passes straight through stainless steel, aluminium, plastic, glass and brass as though they were not there.

That single property solves a class of sealing problem that nothing else addresses cleanly, and it is why magnetic switches survive in positions where other technologies are replaced every few months.

What that actually buys you

The sensor goes outside. The magnet goes inside. Nothing penetrates the wall.

Consider a pneumatic cylinder. The piston position needs to be known. An inductive sensor cannot see through the aluminium barrel. A magnetic switch mounted on the outside detects the magnet in the piston with no penetration, no seal and no wetted part. The same logic applies to a stainless steel vessel with a float inside, to a sealed gearbox, and to any hygienic enclosure where a fitting would create a cleaning problem.

There is a second benefit that matters in dirty plant: because the sensor does not need line of sight and does not care about the material between it and the magnet, dust, product build-up, paint and condensation are all irrelevant. A magnetic switch behind a layer of cement dust works exactly as well as a clean one.

The D33C range

Our magnetic proximity switches come in M12, M18 and M30 bodies, NPN three-wire, 30 mA, short-circuit protected:

  • D33C-12MD-NM-3S — M12
  • D33C-18MD-NM-3S — M18
  • D33C-30MD-NM-3S — M30

Plus speed and direction variants, carrying an SD suffix:

  • D33C-18MD-NM-3S-SD — M18 with speed and direction
  • D33C-30MD-NM-3S-SD — M30 with speed and direction

The output rating is the thing to watch

This range is rated 30 mA, not the 200 to 300 mA of the D30C inductive or capacitive ranges. It is designed to feed a controller input.

Connecting one directly to a contactor coil or a relay is the single most common misapplication of this series. It will either fail immediately or, less helpfully, work for a while and then fail. If the signal must switch a load, route it through a PLC output or an interposing relay driven by something rated for it.

Speed and direction in one sensor

Detecting rotation direction requires two signals in quadrature. Traditionally that meant two sensors, mechanically aligned to a precise offset — and holding that alignment in an industrial environment, through vibration and maintenance, is genuinely difficult.

The SD variants provide both channels in a single housing, with the offset fixed at manufacture. One sensor, one mounting, no alignment to lose. For reversible conveyors, hoists, and any drive where reverse rotation is a fault condition, this is the more robust engineering answer.

Our guide to speed and underspeed monitoring covers the target geometry and controller requirements.

Where magnetic switches earn their place

  • Pneumatic and hydraulic cylinder position — piston magnet detected through the barrel
  • Level switching in stainless or plastic vessels — magnetic float inside, sensor outside, nothing wetted
  • Hygienic applications — no penetration means no crevice and no cleaning problem
  • Door, hatch and guard position — magnet on the moving part, sensor on the frame, tolerant of alignment
  • Rotation and speed monitoring in wet or dusty plant where optical sensing fails
  • Explosion-hazard adjacent areas where keeping electronics outside the enclosure is preferable
  • Through-wall sensing generally, wherever drilling is undesirable

The constraints, honestly

You need a magnet on the target. Where one is already present — a cylinder piston, a magnetic float — this is free. Where it is not, you are adding a component, and it must be fixed securely enough to survive the application.

Ferrous material between sensor and magnet blocks it. The technology passes through non-ferrous walls. A steel wall will shunt the field. Check the wall material before designing around this.

Stray magnetic fields interfere. Near large motors, welding equipment or magnetic separators, consider whether the environment is magnetically clean.

Magnet strength and orientation matter. Sensing distance depends on the magnet, not only the sensor, and magnets have polarity. A magnet fitted the wrong way round will not be detected, which produces a puzzling commissioning fault.

Choosing between magnetic and inductive

Magnetic when you need to sense through a non-ferrous wall, when the environment is wet or dirty enough to defeat other technologies, when a magnet is already present on the target, or when you need direction as well as speed.

Inductive when the target is already ferrous metal and directly accessible, when you need higher output current to drive a load, or when adding a magnet is impractical. It is also cheaper.

Specifying

Tell us the wall material and thickness the sensor has to see through, whether a magnet is already present and if so its type and orientation, the required sensing distance, whether direction sensing is needed, and what the output feeds. For cylinder applications, the cylinder make and bore usually identifies the magnet arrangement.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

NAMUR Control Units, Barriers and Relays: Specifying the Whole Loop

A NAMUR sensor has no output transistor and cannot drive anything. The amplifier is not an accessory — it is half the instrument, and it is where the diagnostics actually happen.

A NAMUR proximity sensor cannot be wired to a PLC input. It has no output transistor and drives nothing. What it does is vary the current it draws from a nominal 8.2 V supply, and something has to provide that supply, interpret the current and turn it into a usable signal.

That something is the control unit, and treating it as an accessory rather than half the instrument is the most common mistake in NAMUR specification.

What the control unit does

Four jobs:

Supplies the sensor. A nominal 8.2 V, current limited.

Interprets the current. Above roughly 2.1 mA means undamped — no target. Below roughly 1.2 mA means damped — target present. The amplifier applies the threshold and produces a clean output.

Detects faults. Both normal states sit inside a narrow band, so anything outside it is a fault rather than a state. Near-zero current means a broken wire. Very high current means a short circuit. This is the property that makes NAMUR worth using even outside hazardous areas — a conventional three-wire sensor cannot distinguish between no target and cut cable, because both produce no output.

Provides isolation. In a hazardous-area installation the amplifier also limits the energy reaching the field circuit, which is what makes the loop intrinsically safe.

The Accent NAMUR control unit

Our NAMUR control unit converts the low-current sensor signal into a relay switching action, and works with either inductive or capacitive NAMUR sensors.

The architecture is the standard one: the sensor sits in the hazardous area and connects by two wires to the control unit, which is mounted in the safe area or inside a flameproof enclosure. That physical separation is the point — the only thing in the hazardous area is a two-wire device with no stored energy of consequence.

Three LEDs on the front fascia show power, cable fault and relay status. The cable fault indicator is the visible expression of the diagnostic band, and it is genuinely useful in service: a maintenance technician can see at a glance whether the problem is the sensor, the wiring or the logic, without a multimeter.

For non-hazardous applications where you want a switching amplifier without the intrinsic safety function, we also supply a standard proximity control unit. The full range sits under control units.

Relay output, and what it means for your design

A relay output gives you a volt-free contact, which has practical consequences worth planning for.

It suits any input. AC or DC, any voltage within the contact rating, PLC input or contactor coil. On retrofit work into older AC panels this matters, because there may be no DC logic anywhere.

It provides galvanic separation between field and control circuits.

It has a finite mechanical life. On a position interlock that operates a few times a shift, irrelevant. On something switching every few seconds, calculate the operations and check it against the contact life. If the count is high, a solid-state output is the better choice.

It has a switching time. Milliseconds rather than microseconds. Fine for process interlocks, not suitable for high-speed counting.

Specifying the loop rather than the parts

Six things to establish together rather than separately:

  1. How many sensors, and therefore how many amplifier channels. Multi-channel units save DIN rail space where there are several.
  2. Where the amplifier goes — safe area or flameproof enclosure — and what panel space is available.
  3. What the output drives, with its voltage and current, so the contact rating can be confirmed.
  4. Operations per hour, to check relay life against the duty.
  5. Cable length and type, because intrinsic safety calculations depend on cable capacitance and inductance, and a long run changes the assessment.
  6. Whether line fault detection must be wired through to the control system rather than only indicated locally. An LED nobody looks at is not a diagnostic; a fault contact routed to the PLC is.

That last point is worth dwelling on. The main practical advantage of NAMUR over conventional sensing is fault detection, and a great many installations throw it away by leaving the fault output unconnected. If you are paying for the diagnostic capability, wire it up.

The sensors

Our NAMUR inductive proximity switches cover M12, M18 and M30 with sensing from 4 mm to 15 mm: D20C-1204-NA, D20C-1805-NA, D20C-1808-NA, D20C-3010-NA and D20C-3015-NA.

Order sensor and amplifier together. Buying them from separate sources is how installations end up with a loop nobody can certify, and the saving never justifies it.

Hazardous area requirements

If the installation is in a classified area, the zone, gas group and temperature class come from your area classification document, and the approval scheme comes from the project specification. Our guide to specifying intrinsically safe NAMUR loops covers what to confirm, and the difference between ATEX, IECEx, UL and CSA.

Tell us the zone and the scheme when you enquire and we will confirm what we can supply against it, and what documentation comes with it.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Extended-Range Inductive Sensors: When Standard Sensing Distance Is Not Enough

Four ways to get more sensing distance out of an inductive switch — larger body, unshielded construction, a better target, or moving the target. And the point at which you should change technology instead.

The enquiry usually arrives in the same form: we need an inductive sensor with more range than the one we have. It is a reasonable request and there are four legitimate ways to satisfy it — plus a point at which the right answer is a different technology altogether.

Why inductive range is limited at all

An inductive sensor works by generating a high-frequency field at the sensing face and detecting the energy lost when a conductive target enters it. Field strength falls off sharply with distance, so the usable range is set primarily by coil diameter. A bigger coil produces a field that reaches further.

Everything below follows from that.

1. Use a larger body

The most direct route. Across the D30C range, sensing distance rises with body size:

  • M8 — shortest
  • M12 — 4 mm
  • M18 — 5 mm and 8 mm
  • M30 — 10 mm and 15 mm
  • M36 — 20 mm
  • M50 — 30 mm

Thirty millimetres from an M50 is the practical ceiling for standard inductive sensing. If the geometry allows a larger body, this is the cheapest and most reliable answer, and it comes with a bonus: the extra standoff tolerates dust, scale and mechanical slop far better than a short-range sensor mounted close.

2. Use an unshielded sensor

A shielded sensor has a metal sleeve around the coil that concentrates the field forward, which allows flush mounting in metal at the cost of range. An unshielded sensor lets the field spread and reaches noticeably further in the same body size.

The price is mounting freedom. An unshielded sensor needs a clear zone around the sensing face — mount it flush in a steel bracket and it detects the bracket, permanently. That failure presents as a sensor stuck on, and gets misdiagnosed as a faulty sensor regularly.

Our note on shielded versus unshielded sensors gives the clearance requirements.

3. Fix the target

This is the option people skip, and it is frequently the best one because it costs nothing.

Rated sensing distance is quoted against a standard mild steel target of a defined size. Two things reduce it in practice:

Material. Stainless steel, aluminium, brass and copper are all detected at less than the rated distance, each by a different factor. If you are sensing aluminium at what you believed was 80 percent of rated range, you may actually be at the limit. Our note on reduction factors for different metals has the numbers.

Size. A target smaller than the standard is detected at reduced distance. Enlarging it — adding a mild steel flag or tab to an aluminium component — often recovers all the range you were missing, for the price of a bracket.

Before specifying a bigger sensor, check whether a bigger target solves it. It usually does, and it is almost always cheaper.

4. Move the sensor

Obvious, and worth stating. The distance that matters is between the sensing face and the target at its closest approach. A mounting position 10 mm closer is worth more than any specification change, and often available once someone looks at the bracket rather than the catalogue.

When to stop and change technology

Past about 30 mm, pushing inductive sensing is the wrong exercise. The alternatives:

Photoelectric — ranges from 100 mm to 20 metres depending on mode, and works on non-metallic targets. Needs reasonable cleanliness, and mode choice matters; see the D31C range.

Capacitive — for non-metallic targets at short range, and the only practical answer for sensing through a non-metallic wall. See capacitive sensing for plastic and powder.

Magnetic — senses a magnet at greater distance than an inductive sensor senses steel, and works through non-ferrous walls. Requires a magnet on the target, which is a constraint but sometimes an easy one.

Position transducer — if what you actually want is not presence at a distance but continuous position, no proximity switch will give it. The Novotechnik range covers that properly.

Sensitivity is not the whole story

One caution about chasing maximum sensitivity. The rated sensing distance is a nominal figure; the assured operating distance you should design to is shorter, because of manufacturing tolerance, temperature drift and supply variation.

A sensor set up at the very edge of its range works on the bench and becomes intermittent in service — typically in the hottest month, which makes it look like an environmental fault rather than a specification one. Design to the assured distance and leave margin.

What to send us

The distance you need, the target material and size, whether the sensor can be mounted non-flush, the available body size, and the environment. If you are currently marginal rather than starting fresh, tell us what you have and what it is doing — an intermittent sensor and a sensor that never triggers are different problems with different answers.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Speed, Rotation and Underspeed Monitoring: Choosing the Right Sensor

Underspeed detection is a protection function, not monitoring. What sets the maximum countable speed, why the target geometry matters more than the sensor, and where direction sensing earns its place.

Speed monitoring covers three distinct jobs that get treated as one: counting pulses to measure rate, detecting that something has stopped or slowed when it should not have, and establishing which way a shaft is turning. The sensor requirements differ, and specifying for the wrong one is a common cause of intermittent faults.

Underspeed detection is protection, not monitoring

Worth separating clearly. A speed readout on an HMI is information. An underspeed trip on a bucket elevator or a mill roller is a protection function — it exists because a stalled or slipping drive under load damages itself, and in dusty plant can start a fire.

Protection functions deserve the fail-safe treatment. Ask what happens when the sensor cable is cut: if the answer is that the machine reads zero speed and trips, good. If it reads nothing and the logic interprets nothing as fine, the protection is not protection.

What limits the maximum countable speed

Three things, and only one of them is the sensor.

The sensor switching frequency. A rated figure in hertz. The sensor cannot produce more transitions per second than this, and running near the limit gives degraded, uneven pulses rather than a clean failure.

The target geometry. This is usually the real constraint and it is under your control. Pulses per second equals teeth multiplied by revolutions per second. A 60-tooth wheel at 3000 rpm demands 3000 Hz; a 6-tooth wheel at the same speed demands 300. If you are near the sensor limit, reducing the tooth count is easier than changing the sensor — provided the resolution still suits the application.

The controller input. An ordinary PLC digital input scanned every 10 ms cannot count 3000 Hz. It needs a high-speed counter input or a dedicated speed monitoring relay. This is the step most often missed, and it produces the characteristic symptom: counts correct at low speed, drifting low as speed rises.

Target design matters more than people expect

For an inductive or magnetic sensor counting a toothed wheel, the tooth and gap need to be comparable in size to the sensing face. Teeth that are too fine relative to the sensor produce a weak, mushy signal because the sensor never fully sees a gap.

Rules of thumb worth applying: make tooth width and gap width roughly equal, keep both at least as wide as the sensor face, and mount at a consistent air gap well within the sensing distance. A wheel that runs out radially gives a varying air gap and an output that is fine at one point of the revolution and marginal at another.

Direction sensing

A single sensor on a toothed wheel tells you the shaft is turning, not which way. Where direction matters — a reversible conveyor, a hoist, a mill that must not run backwards — you need two channels in quadrature, so the controller can compare which one leads.

The speed-and-direction variants in the D33C range provide this in a single sensor rather than requiring two units to be mechanically aligned. Given how difficult it is to hold quadrature alignment between two separately mounted sensors in an industrial environment, that is usually the better engineering answer.

The part numbers carry an SD suffix — D33C-18MD-NM-3S-SD is the M18 version, D33C-30MD-NM-3S-SD the M30.

Mind the output current

One specific and avoidable mistake. The D33C range is rated 30 mA, not the 200 to 300 mA of the general-purpose switching ranges. It is built to feed a controller input, not to drive a contactor coil or a relay directly.

Wiring one to a relay coil will either fail immediately or, worse, work marginally and fail later. If the speed signal needs to switch a load, take it through a controller or a speed monitoring relay. Our part number guide lists the output rating for each series.

Choosing the sensing technology

Inductive — for a ferrous toothed wheel, gear or keyway at moderate speed. Robust, cheap, tolerant of dust between sensor and target. The D30C range covers it.

Magnetic — senses through non-ferrous material, so the sensor can sit outside a stainless or aluminium cover with nothing exposed. This is why magnetic types dominate in wet, dusty and washdown positions.

Photoelectric — where the target is non-metallic or the standoff is large. Needs a clean environment, which rules it out of most speed monitoring positions in heavy industry.

Typical applications

  • Bucket elevator underspeed — protection against belt slip, in dusty and fire-sensitive plant
  • Conveyor belt slip and drift
  • Mill roller underspeed in sugar and steel plants
  • Fan and blower rotation confirmation, often interlocked with a process
  • Reversible drive direction confirmation
  • Production counting on packaging and assembly lines
  • Shaft rotation confirmation on pumps and gearboxes

Specifying

Send us the maximum and minimum speed, the target — material, tooth count, tooth and gap dimensions, or whether it is a single keyway — the available air gap, whether direction is needed, the environment, and what the signal feeds. If the application is an underspeed trip rather than a readout, say so, because it changes the fail-safe requirement.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Potentiometric Rotary Sensors and Sensor Kits for OEM Integration

If you build the mechanics yourself, a sensor kit is cheaper and more compact than a packaged transducer. What a resistance element and wiper set gives you, and what you take responsibility for.

Most position sensors are sold as complete units: housing, bearing, shaft, seals and electronics, ready to bolt on. For an OEM building a few hundred machines a year, that packaging is sometimes the wrong product. You already have a housing, you already have a bearing, and you are paying for someone else version of both.

A sensor kit is the alternative — the measuring element and wiper supplied as components, for mounting into your own mechanics. Accent supplies these from both Contelec and Novotechnik as authorised distributor for India and SAARC.

What a sensor kit actually is

A potentiometric sensor kit is an absolute resistance element and a matched wiper assembly, designed to be installed into a closed device that the machine builder provides. Position is read as a voltage ratio across the element, exactly as in a packaged transducer — the difference is who supplies the mechanics.

The range we supply includes:

  • PTN and PTX — absolute potentiometric resistance elements and wipers, for mounting in a closed device
  • PRS — resistance element and wiper combination with high accuracy
  • PTP — potentiometric position transducer in a cost-optimised compact design, where you want a packaged unit but a small and inexpensive one

What you gain

Cost. You are not buying a housing, a bearing and a shaft seal you already have. On volume production this is the main driver.

Space. A kit integrated into existing mechanics is substantially more compact than a packaged transducer bolted onto them. Where the machine is already tight, this is sometimes the only way position measurement fits at all.

No coupling. A packaged rotary transducer needs coupling to the shaft, and that coupling introduces backlash, misalignment and a wear point. An integrated element rides on the shaft you already have.

Ingress protection by design. If the element sits inside a housing you have already sealed, the sensor inherits that sealing rather than needing its own.

What you take responsibility for

Being direct about this, because it decides whether a kit is appropriate.

Bearing quality and alignment. In a packaged transducer the manufacturer controls the relationship between shaft and element. With a kit, you do. Radial play translates directly into wiper tracking error, and a worn bearing produces a noisy output that looks like a failed sensor.

Wiper pressure and contact geometry. Specified by the manufacturer and set by your assembly. Too light and the contact becomes intermittent; too heavy and the element wears prematurely.

Contamination control. The element is exposed to whatever is inside your housing. Swarf, condensation and grease migration all cause problems that a sealed packaged unit would have excluded.

Assembly consistency. The measurement is only as repeatable as your build process. This needs a documented assembly procedure and an end-of-line check.

When a kit is the right decision

Yes — volume production, an existing housing with a well-supported shaft, space constrained, and an assembly process capable of holding the tolerances.

No — low volume or one-offs, where the engineering effort is not repaid. Retrofits onto existing machines. Harsh or contaminated environments where a sealed packaged unit is safer. Anywhere the assembly cannot reliably hold wiper geometry.

Packaged rotary alternatives

If a kit is not right, the packaged potentiometric rotary range covers most requirements:

  • IP-6000 — absolute high-precision potentiometric rotary sensor, robust and sealed
  • IPX-7900 — high-precision potentiometric rotary for harsh conditions, available to IP69
  • GP — high-precision potentiometric rotary with reduction gear, for measuring across more than one input revolution
  • AW-360 — high-precision rotary in a robust design with gap-free output voltage across the full turn, useful where the measurement must not have a dead band at the wrap point
  • SP-2800 — compact and robust absolute potentiometric rotary, straightforward to install and adjust
  • F200 — absolute inductive transducer with centering collar and integrated sealed hybrid electronics, where a non-contacting element is preferred

The gap-free question

Worth understanding before specifying any single-turn rotary sensor. Most potentiometric elements have a small dead band at the point where the track ends and begins again — a few degrees where the output is undefined. If your measurement never crosses that point, it does not matter. If the shaft rotates continuously through it, the output jumps.

Where that matters, specify a gap-free type such as the AW-360, or a touchless design. It is a cheap thing to get right at specification and an expensive thing to discover at commissioning.

Getting a recommendation

For a kit, send us the shaft diameter, the available space, the measuring angle, the bearing arrangement, and your annual volume. For a packaged unit, the mounting arrangement, measuring angle, required accuracy, output and environment. If you have a drawing of the housing the sensor has to live in, that answers most of it at once.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Novotechnik Multi-Turn Rotary Sensors: MB1, MC1, MZ1 and RMB Compared

A multi-turn sensor knows how many revolutions it has made, and True-Power-On means it still knows after the power has been off — no battery, no gear train, no homing run.

A single-turn rotary sensor measures position within one revolution. Turn the shaft past 360 degrees and it starts again at zero. For a valve actuator or a throttle that is exactly right. For a crane hoist, a leadscrew, a winch or a steering column, it is useless — you need to know which revolution you are on.

That is what a multi-turn sensor provides, and the interesting question is how it remembers.

True-Power-On: why it matters

Traditional multi-turn designs count revolutions. That works while powered. Remove the power and the count has to be preserved somehow, which historically meant one of two compromises:

A battery, which keeps the counter alive. Batteries fail, and when one does the position is lost — usually discovered at the worst moment, and requiring a re-reference before the machine can move safely.

A mechanical gear train, which stores the turn count physically. No battery, but gears add size, backlash and a wear mechanism.

Novotechnik NOVOTURN technology takes a third route. The sensor determines absolute position across the full multi-turn range at power-up, without a battery and without a gear train. If the shaft is moved while the power is off — by hand, by gravity, by a load slipping — the sensor reports the true new position when it powers up, not the position it remembers.

For anything where an unexpected movement during a shutdown is possible, this is the difference between resuming safely and needing a manual re-reference.

The four series

MB1-3600 — absolute non-contacting multi-turn with True-Power-On NOVOTURN, in a 36.5 mm all-metal housing. The all-metal construction is the reason this one gets specified for rough duty. Available with CANopen and IO-Link.

MC1-2800 — NOVOTURN multi-turn with smart sensor functions, in a more compact 28 mm format. Also available with CANopen and IO-Link. The choice where space is constrained.

MZ1-2200 — NOVOTURN multi-turn with smart sensor functions in the smallest format of the three, 22 mm. CANopen available. For tight installations where an MC1 will not fit.

RMB-3600 — absolute non-contacting NOVOHALL multi-turn in a 36.5 mm all-metal housing, with analogue and digital interfaces and several versions available. NOVOHALL rather than NOVOTURN, so confirm the power-off behaviour against your requirement if the shaft can move during shutdown.

Smart sensor functions

The MC1 and MZ1 carry what Novotechnik describes as smart sensor functions. In practice this means parameters that would traditionally be fixed at manufacture — measuring range, zero point, direction of rotation, output scaling — can be configured rather than ordered.

Two consequences worth planning around. Commissioning gets faster, because the sensor is adjusted to the machine rather than the machine to the sensor. And spares holding gets simpler, because one configurable part can cover several positions that would otherwise need distinct part numbers.

If you hold spares across a fleet, ask about this specifically — it often reduces the number of variants you need to stock.

Choosing between them

  1. Start with the housing size. 36.5 mm, 28 mm or 22 mm. Mechanical space usually decides this before anything else does.
  2. Then the interface. CANopen across all three NOVOTURN series, IO-Link on MB1 and MC1, analogue and digital on RMB.
  3. Then robustness. The all-metal 36.5 mm housings of MB1 and RMB suit exposed and mobile applications.
  4. Then configurability. If you want smart sensor functions, MC1 or MZ1.

Where multi-turn is the right answer

  • Crane and hoist position — drum rotation over many turns, where the load position must be known immediately at power-up
  • Leadscrew and spindle position — linear motion driven through many revolutions
  • Winch and cable drums
  • Steering angle on mobile machinery, where lock to lock exceeds one turn
  • Multi-turn valve actuators — gate and globe valves that take many turns to stroke
  • Roll gap and screwdown adjustment in rolling mills

The common thread is that the mechanism travels through more than one revolution and the machine has to know where it is without a homing move.

When a single-turn sensor is enough

If total travel stays within one revolution, use a single-turn sensor — it is simpler and cheaper. The single-turn range covers that, including the RSC-2800 and RFC-4800.

Where a gearbox reduces a multi-turn mechanism to under one revolution at the measuring point, a single-turn sensor also works — but check the backlash, because it appears directly in your position reading.

Specifying

Send us the total number of revolutions, the resolution required, whether the shaft can move while the power is off, the interface your controller expects, the mechanical arrangement and available space, and the protection rating needed. Accent is the sole authorised Novotechnik distributor for India and SAARC.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Novotechnik Linear Position Transducers Compared: Which Series to Specify

The Novotechnik linear range spans four measurement technologies and a dozen mechanical formats. Three questions narrow it to one or two candidates in about a minute.

The Novotechnik linear position transducer range covers four distinct measurement technologies across more than a dozen mechanical formats. Approached as a catalogue it is bewildering. Approached as three questions it resolves quickly.

The questions are: how is it mounted, how long does it have to last, and does anything need to be inside a cylinder.

The four technologies

Potentiometric — a precision conductive plastic track with a wiper. Simple, absolute, direct DC output, no conditioning electronics, lowest installed cost. The wiper contacts the track, so there is a wear mechanism, though Novotechnik designs use a decoupled wiper tap and pendular fixed slide bearing specifically to give stick-slip-free movement and long life.

NOVOSTRICTIVE (magnetostrictive) — non-contacting. A magnet moves along a waveguide and position is derived from the timing of a returned pulse. No wear in the measuring path, long strokes available, and it can be built as a rod for installation inside a hydraulic cylinder.

NOVOPAD (inductive) — non-contacting inductive measurement in a compact profile. A wear-free alternative in a smaller package than magnetostrictive.

Integrated signal processing types — the TE1 family, which includes signal processing in the transducer and can be replaced without recalibration. That last property is worth noting for maintained plant: swapping the unit does not mean a commissioning exercise.

Question one: how does it mount

This narrows the field faster than anything else.

Rod style, actuated by a moving machine element

  • TEX rod type — potentiometric, pendular fixed slide bearing, decoupled wiper, long life
  • TX2 — potentiometric with a double-supported actuating rod, high adjustment speed. Available with pivot head mounting or mounting clamp.
  • LWH and LWG — potentiometric, the general-purpose workhorses of the range
  • LWX-003 and LWX-004 — the LWX-004 with a shaft-protected design for dirtier positions

Side actuated

  • TLH — potentiometric, side actuated, IP40 to IP54, rated from below minus 30 to above plus 100 degrees Celsius

Spring return, where the machine pushes but does not pull

  • TR and TRS with return spring, TEX with return spring, TE1 with return spring, LS1 with return spring

A return spring matters more than it sounds. If the actuating element only pushes the rod and relies on it following back, the spring is doing the measurement on the return stroke — and if it is absent or too weak for the speed, the reading lags.

Profile designs

  • TP1 — NOVOSTRICTIVE magnetostrictive in a robust profile, non-contacting
  • LS1 — NOVOPAD inductive, compact profile, double-sided supported actuating rod

Inside a hydraulic cylinder

  • TH1 — NOVOSTRICTIVE rod style, designed for integration into cylinders

Sensor kits for integration into your own housing

  • PTX — potentiometric sensor kit, for OEMs building the transducer into their own mechanics

Question two: how many cycles

This decides contacting against non-contacting.

For machine positioning, valve feedback, press setup and general industrial measurement at moderate cycle rates, potentiometric is entirely adequate and considerably cheaper installed. The objection people raise — that the wiper wears — is usually based on experience with wirewound potentiometers rather than conductive plastic elements with decoupled wipers.

For continuous high-cycle duty, for washdown environments, or where a failure is expensive enough that the wear mechanism is unacceptable in principle, specify NOVOSTRICTIVE or NOVOPAD. The cost difference buys the removal of the only wear path.

Question three: cylinder integration

If the measurement has to happen inside a hydraulic cylinder, the answer is TH1 and the other questions become secondary. A rod-style magnetostrictive transducer installed in a gun-drilled cylinder rod gives you position with nothing exposed to the outside world at all — no rod to be damaged, no seal to fail, no alignment to lose.

This is the right answer for mobile machinery, presses and any cylinder in a position where an external transducer would be destroyed.

Interfaces

Most of the range offers ratiometric or analogue output as standard. TH1, TP1 and TM1 also offer CANopen and IO-Link, which is worth knowing if the machine architecture is bus-based — see CANopen position sensors.

A quick way through

  1. Inside a cylinder? TH1.
  2. OEM integration into your own housing? PTX.
  3. High cycles, wet, or wear unacceptable? TP1 or LS1.
  4. Needs to be replaceable without recalibration? TE1.
  5. Everything else — LWH, TEX or TX2 depending on mounting, with a return spring variant if the actuator only pushes.

What to send us

Stroke length, mounting arrangement, whether the actuator pushes only or both ways, expected cycles per day, required accuracy as a number, output needed, protection rating, and temperature range. A sketch of the mechanical arrangement is worth more than any of them individually. Our note on selecting a linear position transducer covers the mechanical decisions in more depth.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Sensors for Packaging and Pharmaceutical Machinery

Packaging lines ask sensors to do the two things they are worst at: detect transparent material, and do it at high speed. Plus survive changeover and a validated cleaning regime.

Packaging and pharmaceutical machinery asks sensors to do the two things they find hardest — detect transparent and low-contrast material, and do it fast — while surviving frequent format changeovers and, in pharma, a cleaning regime with documentation attached.

Here is how the specification usually needs to go.

Transparent material is the defining problem

Clear film, PET bottles, glass vials, blister foil backing and cellophane overwrap are all close to invisible to a diffuse photoelectric sensor. The light passes through, very little comes back, and detection is marginal in a way that varies with ambient light and film tension.

The reliable answer is through-beam. Emitter and receiver facing each other, the target detected by beam interruption rather than reflection. Even a transparent object attenuates the beam measurably, and with sensitivity set correctly this is stable where diffuse sensing is not.

Where a through-beam arrangement is not mechanically possible, retro-reflective is second best, but expect to spend commissioning time on sensitivity and expect it to need revisiting when the film supplier changes. The D31C range covers all three modes in M18 and M30.

Speed, and what it means for switching frequency

A packaging line running 300 packs a minute gives a sensor 200 milliseconds per pack, and the detection window inside that is much shorter. Two things have to be fast enough: the sensor, and the controller reading it.

Switching frequency is a specification parameter that gets ignored on slow applications and becomes decisive here. If the sensor is counting, specify against the maximum line rate with margin, not the nominal rate.

The failure mode is characteristic: counts that are correct at low speed and drift low as the line speeds up. If you are seeing that, the sensor or the input scan rate is the cause, not the mechanism.

Small targets and tight geometry

Packaging machinery is compact. There is rarely room for an M30 body, and the targets — a tablet, a cap, a label edge — are small. This pushes towards M8 and M12 inductive bodies for metal targets, and towards photoelectric with a well-defined beam for everything else.

Where the target is small relative to the sensing field, the sensor may respond weakly or inconsistently. Specify the target size when you enquire; it changes the recommendation more than people expect.

Changeover survives or it does not

A line that changes format several times a week puts mechanical stress on everything adjustable. Sensors get knocked, brackets get moved and not moved back, and cables get caught.

Three things help:

  • Mount out of the changeover path wherever the geometry allows. The best protection is not being in the way.
  • Use positive mechanical location — a dowel or a machined seat rather than a slot — so a sensor that is removed goes back in exactly the same place.
  • Specify connector versions rather than fixed cable where sensors are routinely removed. An M12 connector survives repeated disconnection; a cable that is pulled through a machine frame every changeover does not.

Hygiene and cleaning in pharma

On pharmaceutical lines the cleaning regime is validated, which means it will not be adjusted to suit a sensor. Specify to survive it as it is.

  • Stainless steel bodies, flush mounting, no crevices, no exposed threads collecting product, no horizontal ledges.
  • Chemical compatibility with the actual cleaning agent — including the cable sheath, which is the component most often overlooked and quite often the first to degrade.
  • Rating against the wash, not the process. Where high-pressure hot washdown is used, see IP69K washdown specification. The connector matters as much as the sensor: an IP69K sensor on an IP65 connector is an IP65 installation.
  • Cable entries pointing down. Standing water on an upward-facing gland defeats any rating eventually.

Documentation

Pharmaceutical and export machinery frequently needs component documentation as part of the machine file — declarations of conformity, material certificates, and in some cases traceability to a production batch.

Establish what your quality system requires before ordering rather than during qualification. Components bought through unofficial channels are commonly untraceable, which is a difficult thing to discover late. Our note on buying direct versus through a channel covers how to avoid that.

Typical sensor map on a packaging line

  • Product presence and gap detection — through-beam photoelectric, dark-on
  • Counting — photoelectric with switching frequency specified against maximum line speed
  • Metal cap, can and foil detection — D30C inductive in M8 or M12
  • Carton, plastic and non-metal detection — capacitive, or photoelectric where the target moves fast
  • Guard and interlock positions — normally closed, so a cut cable stops the machine
  • Format part identification — inductive presence sensing to confirm the right tooling is fitted, which prevents an entire class of changeover error
  • Servo and axis position feedback — position measurement rather than switching; see the Novotechnik linear range

Specifying

Send us the target — material, size, whether it is transparent or reflective — the line speed in units per minute, the available mounting space, the cleaning regime, and the output your controller expects. For transparent targets, a sample or a photograph is worth more than a description.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Sensors for Cement Plants: Dust, Heat and Very Long Cable Runs

Cement dust is abrasive, conductive when damp, and gets absolutely everywhere. Combine that with kiln heat and 200 metre cable runs, and three ordinary specification choices become wrong.

Cement plants present a combination that is unusual even among heavy industries: extremely abrasive dust everywhere, intense radiant heat in one area, and cable runs long enough that the electrical specification changes.

Each of those individually is manageable. Together they invalidate a few habits that work fine elsewhere.

Dust is the dominant problem

Cement dust is abrasive, it is fine enough to penetrate anything imperfectly sealed, and when it takes up moisture it becomes conductive and mildly cementitious. That last property is the one that catches people out — dust that has been damp and dried is not dust any more, it is a thin layer of set material, and it does not brush off.

Three consequences for specification:

Optical sensing is difficult. Lenses foul fast. Where photoelectric sensing is unavoidable, use through-beam mode, specify substantially more range than the gap requires so there is margin to lose, and plan for cleaning access. Diffuse mode in a cement plant is rarely a good decision.

Capacitive sensing needs care. Damp dust on the sensing face reads as a target. Where capacitive sensing is genuinely needed, mount so the face cannot collect material.

Inductive sensing is the workhorse, because dust between the sensor and a metal target affects it very little. This is why most of what actually survives in a cement plant is inductive.

Long cable runs change the electrical specification

Cement plants are physically large. A sensor on a conveyor gallery may be 150 or 200 metres from the nearest panel, and at that distance two things that are normally irrelevant become decisive.

Voltage drop. Over a long run at small conductor size, the supply reaching the sensor is measurably lower than the supply leaving the panel. Check the sensor still has adequate supply voltage at the far end, and size the conductor accordingly.

Noise pickup. A long cable running alongside VFD output cabling is an efficient antenna. Cement plants are full of large drives, and VFD carrier frequencies couple readily into signal cables.

The practical answers: use screened cable and earth the screen at one end only, physically separate signal and drive cabling, and where an analogue measurement is involved prefer a current output over a voltage output — a 4 to 20 mA loop is immune to the voltage drop and far more tolerant of induced noise. For long-distance position measurement, a digital or fieldbus interface removes the problem entirely; see CANopen position sensors.

Kiln area heat

Near the kiln, kiln hood and clinker cooler, radiant heat rather than ambient temperature sets the case temperature. The remedies are the same as in any hot process: increase distance, fit a shield, or provide cooling — in that order of preference, because each step adds something that can fail.

Measure the case temperature at the intended mounting position during normal operation before ordering. It takes ten minutes and prevents a recurring replacement.

Applications through the plant

Conveyors

Belt drift, belt slip, underspeed and pull-cord status account for a large share of the sensor population in a cement plant. Speed and underspeed monitoring is a protection function — a stalled belt under load is a fire risk and a mechanical one.

Magnetic speed sensors from the D33C range are appropriate here, and they tolerate dust better than optical alternatives because they sense through non-ferrous material.

Bucket elevators

Speed monitoring and belt alignment. An elevator that slips or misaligns damages itself quickly, and the sensors that detect it are among the most valuable in the plant.

Chutes and transfer points

Blockage detection. This is where plugged-chute events become spillage events, and where a sensor that works is worth a great deal. The environment is as bad as it gets — material flow, impact, dust — so mount with standoff and protect mechanically.

Gates, dampers and diverter positions

Straightforward D30C inductive switching, specified with generous sensing distance so the standoff can absorb dust build-up and mechanical slop. Normally closed for anything safety-related.

Silo and hopper level

Point level detection at high and low. Where the vessel is metallic, external capacitive sensing is not available and the solution needs to be inside — which changes the technology choice. Tell us the vessel construction when you enquire, because it determines the answer.

Damper and valve position feedback

Where the control system needs actual position rather than open or closed, this is position measurement rather than proximity switching. Rotary sensors from the Novotechnik range cover it, with touchless variants for the dustier positions.

The specification habits worth adopting

  1. Bigger bodies, longer sensing distances, more standoff. M30 and above wherever space allows. The extra clearance is what tolerates dust build-up.
  2. Short-circuit protected outputs — the -3S suffix — on everything. Cable damage is routine over these distances.
  3. Screened cable, earthed one end, separated from drive cabling.
  4. Current or digital outputs for anything analogue over distance.
  5. Mount so faces shed material rather than collect it, and so they can be reached for cleaning.
  6. Standardise. A plant this size with forty variants cannot stock spares properly.

If you want help with the last one, send us the plant sensor list and we will map it to the smallest set of equivalents that covers it.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Sensors for Sugar Mills: Surviving Cane, Juice, Steam and the Season

A sugar mill runs flat out for six months and then stops. That season shape, not the humidity, is what should drive sensor specification — because there is no window to fix anything in February.

Sugar is an unusual industry to specify sensors for, because the operating pattern dominates everything else. A mill runs continuously through the crushing season and then stops for months. During the season, unplanned downtime is expensive and cane is waiting. Outside it, there is time to do anything.

That shape should drive the specification. The question is not what is adequate — it is what will run to the end of the season without attention, because there is no window to fix it in February.

What the environment actually does

Fibre gets everywhere. Cane fibre and bagasse work into every crevice, pack around sensor faces, and bridge gaps that were designed to stay open. On a capacitive sensor, packed fibre reads as a permanent target. On an optical sensor it blocks the lens.

Juice is sticky, and it sets. Sugar-bearing juice dries to a hard deposit. A sensor face that is wiped clean weekly stays fine; one that is not accumulates a coating that changes its behaviour gradually rather than suddenly, which makes the fault hard to attribute.

Steam and humidity are constant. The boiling house runs wet and warm. Thermal cycling between a hot process area and cooler night-time ambient drives moisture into anything imperfectly sealed.

Mill drives vibrate heavily. Cane mills are high-torque, low-speed and rough. Mountings loosen and cables chafe.

Where sensors go, and what to specify

Cane carrier and feed

Belt or chain movement, level in the feed chute, and blockage detection. The requirement here is standoff — the sensor must be far enough from the material stream that fibre does not pack against it, which means specifying a larger body with a longer sensing distance than the geometry strictly needs. An M30 with 15 mm sensing mounted at 10 mm will outlast an M12 with 4 mm mounted at 3 mm, every season.

D30C inductive switches in M30 and above are the standard choice for metal targets on carriers and drives.

Mill roller speed and direction

Underspeed detection on mill rollers is a protection function, not a monitoring nicety — a slipping or stalled roller needs to be detected before something breaks. Magnetic speed sensors from the D33C range handle this, and the speed-and-direction variants are useful where reverse rotation matters.

Note the 30 mA output rating on that series: it feeds a controller input, not a contactor coil directly.

Juice, syrup and molasses level

This is where capacitive sensing earns its place. Juice has a high dielectric constant and is detected easily, and where the vessel wall is non-metallic the sensor can be mounted externally with nothing wetted and nothing to clean.

The caution is specific to this industry: syrup and molasses cling. If product coats the inside of the wall, an externally mounted capacitive sensor reads full permanently. Assess that before committing to the approach — on thin juice it usually works well, on heavy molasses often not.

Centrifugal position and interlocks

Lid position, discharge plough position and safety interlocks. Specify normally closed for anything that is a guard or a safety interlock, so a severed cable produces the stopped state rather than the running one.

Bagasse handling and boiler feed

Conveyor movement, chute blockage and level. Dusty, fibrous and in places warm. Photoelectric sensing is possible but needs through-beam mode and generous range margin, because lenses foul quickly in bagasse dust. Where a mechanical or inductive solution exists, it will usually need less attention.

Boiling house and pan floor

Warm, wet and steamy. Specify for washdown conditions rather than for the nominal ambient, and point every cable entry downward. Our note on IP67, IP68 and IP69K covers what each rating actually tests.

Specify for the season, not the day

Three practical rules that follow from the operating pattern:

Over-specify the sensing distance. The extra standoff is what buys tolerance to fibre packing and deposit build-up. This is the single highest-return decision in a sugar mill.

Standardise the part numbers. A mill with forty sensor variants cannot hold meaningful spares of any of them. A mill with eight can. During the season, being able to substitute from stores in ten minutes is worth more than an optimal specification for each position.

Specify short-circuit protected outputs. The -3S suffix. In an environment with this much vibration and cable chafe, output shorts happen, and an unprotected sensor is destroyed by the first one.

Use the off-season properly

The maintenance window between seasons is the time to do the things that prevent in-season failures: replace sensors that were marginal rather than failed, re-route cables that are chafing, fit guard brackets where something got hit, and rationalise the spares holding.

If you want to do that rationalisation, send us the current sensor list from the plant — part numbers and positions — and we will map it to the smallest set of equivalents that covers the mill. It is a more useful exercise than replacing like for like, and the off-season is when there is time to act on it.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Proximity Sensors for Steel Plants and Rolling Mills: What Survives

In a rolling mill the sensor is rarely what fails first — the cable is. What heat, scale, descaling water and vibration each do to an installation, and how to specify around them.

A steel plant destroys sensors in a small number of very predictable ways. Once you know what they are, specification becomes a matter of designing around each one rather than hoping a high IP rating covers everything.

These are the five failure mechanisms we see, in roughly the order they cause problems.

1. Radiant heat, which is not the same as ambient temperature

The mistake is specifying against the plant ambient. A sensor mounted two metres from hot stock is not at ambient — it is receiving radiant heat continuously, and its case temperature can be far above the air around it.

Three responses, in order of preference:

  • Move it. Distance is the cheapest heat shield there is, and a mounting position half a metre further back often solves the problem permanently.
  • Shield it. A simple steel plate between the sensor and the radiating source blocks the line of sight. Effective and cheap.
  • Cool it. Air purge or water cooling where the first two are not possible. Reliable, but now you have a service that can fail.

Measure the actual case temperature at the intended position during normal production before ordering. It is a ten minute job and it prevents a recurring replacement.

2. Scale

Mill scale is conductive, magnetic and abrasive, and it accumulates on everything. On an inductive sensor face a scale build-up can trigger the sensor permanently, which presents as a sensor that is stuck on and gets replaced unnecessarily.

Mount sensors facing downward or vertically where possible so scale falls away rather than collecting. Where the face must point up, plan for cleaning access, because it will need it.

3. Descaling water and cooling water

High-pressure descaling spray is closer to an IP69K condition than an IP67 one, and it comes with thermal shock: a hot sensor hit by cold water contracts rapidly and draws water past marginal seals. See our note on IP67, IP68 and IP69K for what each rating actually tests.

Specify for the spray, and point cable entries downward. An upward-facing cable gland in a wet area collects standing water and fails eventually regardless of its rating.

4. Vibration and mechanical damage

Mills vibrate, and cobbles happen. Two consequences worth designing for:

Mountings loosen. A sensor that drifts out of position reads intermittently and gets blamed on electronics. Use locknuts on both sides, and check alignment as part of routine maintenance rather than after failure.

Things get hit. A sensor in an exposed position will eventually be struck by stock, by scale, or by a maintenance trolley. Where you cannot move it out of the way, a simple guard bracket costs very little and saves the sensor.

5. The cable, which is what usually actually fails

In our experience of mill installations, the sensor is rarely the first thing to go. The cable is — chafed on a sharp edge, crushed under something, cooked against a hot surface, or pulled out of the gland by thermal movement.

Specify the cable properly. Route it away from heat and away from sharp edges. Support it so the gland carries no weight. Leave a service loop. And where the run is long, consider specifying a made-to-length cable so the first joint is outside the hostile zone rather than inside it.

What to specify where

Position and limit sensing on cold or warm sections — D30C inductive switches, sized with generous sensing distance so the standoff can be increased for heat and scale clearance. M30 and above rather than M12 where space allows.

Hot stock detection and tracking — hot metal detectors, which sense radiated infrared and therefore need no proximity to the stock at all. Specification is a geometry problem; see what to specify before ordering an HMD.

Long-distance presence detection across a pass line — D31C photoelectric in through-beam mode, specified with substantially more range than the gap so there is margin as the lenses foul.

Roll and shaft speed, and direction — magnetic speed sensors from the D33C range, which detect through non-ferrous material and tolerate the environment better than optical encoders.

Screwdown, roll gap and hydraulic cylinder position — this is not proximity switching but absolute position measurement, and it wants a Novotechnik transducer. For high-cycle or wet positions the touchless rotary series are the appropriate choice.

Hazardous areas in the gas plant or by-products section — NAMUR switches with a suitable amplifier. See specifying intrinsically safe NAMUR loops.

Standardise the spares holding

A practical point that matters more than any individual specification. Mills accumulate sensor variety — a dozen manufacturers, forty part numbers, and a stores holding that cannot cover any of them properly.

Rationalising to a smaller number of variants across the plant reduces stockholding, makes substitution possible during a breakdown, and means the maintenance team knows the parts. If you want to do that exercise, send us the current sensor list and we will map it to the smallest set of equivalents that covers it.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Replacing Imported Proximity Switches: How to Cross-Reference Correctly

Cross-referencing a sensor on body size and sensing distance alone is how machines end up with parts that fit and do not work. The six parameters that must match, and the two people forget.

A sensor fails. The label says something from a European or Japanese manufacturer, the lead time is eight weeks, and someone suggests finding an Indian equivalent. That is usually a good idea. It goes wrong when the cross-reference is done on body size and sensing distance alone.

Those two parameters determine whether the part fits. Four more determine whether it works, and two others determine whether it keeps working. Here is the full list.

The parameters that must match

1. Body size and thread

M8, M12, M18, M30, M36, M50. Straightforward, but check thread length as well as diameter — a sensor with a shorter barrel may not reach through a thick bracket, and one with a longer barrel may bottom out.

2. Sensing distance, adjusted for the target

Match the nominal figure, then check what the target actually is. Catalogue sensing distances are quoted against standard mild steel. If the machine senses aluminium or stainless steel, the effective distance is shorter — and if the original sensor was specified with that already accounted for, a nominal match may not be a functional one.

Our note on reduction factors for different metals has the correction figures.

3. Shielded or unshielded

This is the one most often missed, and it fails in a specific and confusing way. A shielded sensor can be mounted flush in metal. An unshielded one senses further but needs a clear zone around the face.

Fit an unshielded sensor into a mounting designed for a shielded one and it triggers on the bracket, permanently. The symptom is a sensor that reads on with nothing in front of it, and it gets diagnosed as a faulty sensor about half the time. See shielded versus unshielded.

4. Output type — NPN or PNP

Must match the input card. A PNP sensor into an NPN input does nothing at all, which at least is obvious. The subtler failure is an input card that accepts both but was configured for one.

5. Contact function — NO or NC

Match the original unless you are deliberately changing the logic. Substituting NO for NC and fixing it in the PLC works, but it leaves a machine whose wiring no longer matches its drawings, and the next person will lose a morning to it.

6. Supply voltage and output current

Confirm the supply range covers what the panel provides, and that the output current rating exceeds what the load actually draws including inrush.

The two that get forgotten

Connection method

Cable or connector. If connector, which one — M12 four-pin is common but not universal, and pin assignment varies. If cable, what length? A replacement with a 2 metre tail where the original had 5 metres means a junction box that was not in the plan.

This is worth specifying rather than accepting, because a made-to-length cable is usually available and removes the problem entirely.

Switching frequency

Rarely checked, occasionally decisive. If the sensor is counting teeth on a rotating shaft or detecting parts on a fast line, the replacement must switch at least as fast as the original. A sensor that is perfectly adequate for a limit position will miss counts on a high-speed application.

If the application is counting or speed sensing, say so — it changes the recommendation, often towards the D33C range.

What to send us

The fastest cross-reference comes from three things:

  1. The full part number from the label, photographed rather than transcribed. Sensor labels use characters that are easy to misread, and a wrong digit sends the whole exercise sideways.
  2. A photograph of the sensor installed, showing the mounting and how close the surrounding metal is. This answers the shielded question, the thread length question and often the target question at once.
  3. What it is sensing, and at what distance.

If you have the machine wiring diagram, the page showing the sensor is more useful than the sensor datasheet.

What you get from switching

Replacing imported sensors with domestically manufactured equivalents changes three things that matter on a maintained asset.

Lead time becomes a production question. No ocean freight, no customs clearance in the critical path.

The part stays available. Imported ranges get rationalised, and distributors change. A part made in Mumbai is subject to neither.

Variants become possible. Cable length, connector type and housing details can be specified rather than accepted — which, on a machine where you are replacing a dozen sensors anyway, is a chance to remove the junction boxes that were only ever there because the standard cable was too short.

Where we would tell you not to switch

If the original is doing something an inductive, capacitive, photoelectric or magnetic switch cannot do — absolute linear or rotary position measurement, for example — then a proximity switch is not the equivalent, whatever the mounting suggests. In that case the right answer is a position transducer from the Novotechnik range, and we will say so rather than sell you the wrong category of device.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

How to Read an Accent Part Number: The Complete Ordering Code Guide

Every Accent part number encodes the whole specification. Once you can read it, you can write the exact part you need onto a requisition without opening a catalogue.

Every Accent sensor part number describes the complete specification of the product. Series, body size, sensing distance, output type, contact function, wiring and protection are all in there. Once the pattern is clear, you can read any part number off a label and write a replacement code without opening a catalogue.

This page is the decoder for the whole range.

The series prefix

The first four characters identify the technology:

  • D30C — DC inductive proximity switch, three-wire. The general-purpose range.
  • D31C — photoelectric switch.
  • D32C — capacitive proximity switch.
  • D33C — magnetic proximity switch, including speed and direction variants.
  • D20C — NAMUR inductive proximity switch, for intrinsically safe duty.
  • A20C — AC two-wire inductive proximity switch.

Inductive, capacitive and NAMUR: D30C, D32C, D20C, A20C

These follow a common pattern:

D30C-1204-NM-3S

D30C Series
12 Body thread in mm — 08, 12, 18, 30, 36 or 50
04 Nominal sensing distance in mm
N Output transistor — N for NPN, P for PNP
M Contact function — M for normally open (make), B for normally closed (break)
3S Three-wire, short-circuit protected. Plain 3 omits the protection.

So the body and sensing distance pair together as four digits. 1204 is M12 with 4 mm sensing. 5030 is M50 with 30 mm. 3015 is M30 with 15 mm.

A20C differs only in the output section, because an AC two-wire sensor has no transistor type. A20C-1808-M-2 is M18, 8 mm, normally open, two-wire.

D20C NAMUR parts carry the NA suffix instead of an output code, because a NAMUR sensor does not switch a load — it changes the current it draws. D20C-1805-NA is M18 with 5 mm sensing, NAMUR output.

Photoelectric: D31C

Photoelectric parts need two extra fields, because sensing mode and range are independent of body size.

D31C-18TB-15000-PL-2S

D31C Series
18 Body thread — 18 or 30
TB Sensing mode — TB through-beam, RR retro-reflective, DR diffuse reflective
15000 Sensing range in mm
P Output — P for PNP, N for NPN
L Logic — L for light-on, D for dark-on
2S Short-circuit protected

Magnetic and speed sensing: D33C

D33C-18MD-NM-3S is an M18 magnetic proximity switch, NPN normally open, three-wire, short-circuit protected, rated 30 mA.

An additional SD suffix indicates the speed and direction variant, used for rotation monitoring where the control system needs to know not just that a shaft is turning but which way. D33C-30MD-NM-3S-SD is the M30 version.

Note the output current: the D33C range is rated 30 mA rather than the 200 to 300 mA of the switching ranges. It is designed to feed a controller input, not to drive a contactor directly. Driving a relay coil from one is a common and avoidable mistake.

Output current by series

  • D30C — 200 mA and 300 mA depending on variant
  • D31C — 200 mA
  • D32C — 300 mA
  • D33C — 30 mA
  • A20C — 200 mA

Check the actual current your load draws. A contactor coil inrush can be several times its holding current, and a sensor sized on the holding figure will fail.

The suffixes that matter most

S for short-circuit protection. The difference between -3 and -3S. Small price difference, prevents the most common field failure. Specify it unless there is a reason not to.

M and B. Make and break — normally open and normally closed. Worth choosing deliberately rather than defaulting: on a safety-relevant interlock, normally closed means a cut cable produces the stopped state.

N and P. NPN and PNP. Determined by your input card, not preference. See PNP versus NPN sensors.

Reading a worn label

If the label on an installed sensor is partly illegible, you can usually reconstruct the code. Measure the thread to get the body size. Count the wires: two means A20C or D20C, three means one of the DC ranges. Trace the output to see whether it sources or sinks. Then send us what you have — a photograph of the sensor in place and its wiring is generally enough for us to identify the part.

Cross-referencing another manufacturer

If you are replacing a competitor part rather than an Accent one, send us the full part number from the label and the application. We will identify the equivalent rather than ask you to work through the decoder — see our guide to replacing imported proximity switches.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

A20C AC Two-Wire Proximity Switches: Retrofitting Panels With No DC Supply

Older Indian plant runs on AC contactor logic with no DC rail anywhere near the machine. The A20C exists for exactly that retrofit — and for the leakage current problem it creates.

A great deal of working plant in India was built around AC contactor logic. There is no 24 V DC rail, no PLC input card, and no convenient place to get one — just a contactor coil that needs switching and a mechanical limit switch that has finally worn out.

Replacing that limit switch with a modern DC three-wire proximity sensor means adding a power supply, finding panel space, and running a new circuit. The A20C exists so you do not have to.

What a two-wire AC sensor is

It wires exactly like a mechanical switch: in series with the load, two wires, no separate supply. The sensor takes its operating power through the load itself. When it switches, current flows to the contactor coil; when it does not, only a small residual current flows.

That makes it a genuine drop-in replacement for a limit switch, a reed switch or a microswitch, with no panel modification at all. For retrofit work on ageing plant this is frequently the difference between a half-hour job and a rewiring project.

The A20C range

Eight body and sensing combinations, each available normally open or normally closed:

  • M12 — 2 mm and 4 mm sensing
  • M18 — 5 mm and 8 mm
  • M30 — 10 mm and 15 mm
  • M36 — 20 mm
  • M50 — 30 mm

All are two-wire, rated 200 mA. The ordering code follows the house pattern:

A20C-1808-M-2 — M18 body, 8 mm sensing, normally open (M for make), two-wire. Substitute B for break to get the normally closed version.

The two things that catch people out

Two-wire AC sensors have two well-known characteristics. Neither is a fault, but both cause confusion when they are not expected.

Residual current. Because the sensor powers itself through the load, a small current flows even when the sensor is off. In most cases the contactor coil ignores it. With a very low-burden load — a solid-state relay input, an electronic timer, some PLC AC input cards — that residual current can be enough to hold the load partially on, or to make an input read permanently true.

The symptom is a contactor that hums, or an input that never clears. The fix is a bleeder resistor across the load to give the residual current somewhere to go. Check the minimum load current your device requires before ordering.

Voltage drop. The sensor drops a small voltage across itself when conducting, because it needs that to operate. With a single sensor this is immaterial. Put three in series for an interlock chain and the drops add, and the coil at the end may not see enough voltage to pull in reliably.

If you are chaining sensors, add up the drops and compare against the coil pull-in voltage. Where the sum is marginal, use DC sensors and a relay instead. Our note on series and parallel connection of proximity switches covers the arithmetic.

When to use AC two-wire, and when not to

Use it for direct replacement of a worn mechanical switch in an AC panel, where the load is a contactor or solenoid with a normal burden, and where you want to avoid adding a DC supply.

Do not use it where the load is electronic and low-burden, where several sensors must be chained in series, where fast switching is required, or where you are building new. On a new machine, specify DC three-wire from the D30C range — more output options, no residual current, no voltage drop, and better diagnostics.

Why this range still matters

Because a very large amount of Indian manufacturing capacity was installed before DC control became standard, and that plant still has to run. A machine from the 1990s with a failed limit switch does not need a control system upgrade. It needs a sensor that fits the wiring that is already there.

The A20C is made in Mumbai to IEC 60947-5-2, so obsolescence is not a concern in the way it is with an imported range that may be rationalised away.

Ordering

Send the body size the existing mounting takes, the sensing distance needed, whether the function is normally open or normally closed, the AC supply voltage, and what the sensor is switching — ideally with the coil rating. If you are replacing a mechanical switch, a photograph of the installation usually answers the mounting questions faster than measurements do.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Accent D31C Photoelectric Switches: Range, Sensing Modes and Ordering

Choosing between diffuse, retro-reflective and through-beam decides reliability more than any other parameter. The full D31C range, what each mode is good at, and how the ordering code works.

When the sensing distance you need is beyond what an inductive switch can reach, or the target is not metal, the answer is usually photoelectric. The D31C range covers that requirement with 72 variants in M18 and M30 bodies, and the single most important decision is not the model number — it is which of the three sensing modes you choose.

Get the mode right and a photoelectric sensor runs for years. Get it wrong and it becomes the device the maintenance team resents.

The three sensing modes

Through-beam puts the emitter and the receiver in separate housings, facing each other. The target is detected when it breaks the beam. This is the most reliable mode by a wide margin: the receiver sees a strong, direct signal, so dust, fog, mist and a dirty lens all have to degrade it a long way before detection fails. It is also the only mode that reliably detects shiny, dark, transparent and irregularly shaped objects, because it does not depend on anything being reflected back.

The cost is installation. Two housings, two mounting brackets, and cable to both sides.

Retro-reflective puts the emitter and receiver in one housing and a reflector opposite. The beam travels out, bounces off the reflector and returns. Detection occurs when the target interrupts it. You get most of the range of a through-beam arrangement with only one electrical connection to make — the reflector needs mounting but not wiring.

The limitation is shiny targets. A polished or reflective object can bounce enough light back to look like the reflector, and the sensor misses it.

Diffuse reflective puts everything in one housing with no reflector at all. The beam reflects off the target itself. Simplest to install, shortest range, and most sensitive to the target surface — a matt black object reflects very little and is detected at a fraction of the distance a white one is. Background objects within range can also trigger it.

The D31C range

Diffuse reflective

  • M18 — 100 mm and 300 mm
  • M30 — 500 mm, 1000 mm, 2500 mm and 3000 mm

Retro-reflective

  • M18 — 1000 mm, 2000 mm, 3000 mm and 5000 mm
  • M30 — 10000 mm, 15000 mm and 20000 mm

Through-beam

  • M18 — 1000 mm, 3000 mm, 5000 mm, 10000 mm and 15000 mm

Every variant is available in all four output combinations, three-wire, 200 mA, short-circuit protected.

Reading the ordering code

A typical part number:

D31C-18TB-15000-PL-2S

  • D31C — photoelectric switch series
  • 18 — M18 body (or 30 for M30)
  • TB — sensing mode: TB through-beam, RR retro-reflective, DR diffuse reflective
  • 15000 — sensing range in millimetres
  • P — output type: P for PNP, N for NPN
  • L — output logic: L for light-on, D for dark-on
  • 2S — short-circuit protected

So D31C-30RR-20000-ND-2S is an M30 retro-reflective unit with 20 metre range, NPN output, dark-on, short-circuit protected.

Light-on or dark-on

This catches people out because the intuitive answer is often the wrong one.

Light-on switches the output when the receiver sees light. Dark-on switches when it does not.

For a through-beam or retro-reflective sensor detecting an object passing through the beam, dark-on gives you an output when the object is present — which is usually what the control logic wants. For a diffuse sensor, light-on gives you an output when the object is present, because the object is what returns the light.

There is also a fail-safe consideration. With through-beam set to dark-on, a failed emitter, a cut cable or a power loss all produce the same state as object present. If that state stops the machine, the failure is safe. If it starts something, it is not. Think this through for the specific function rather than accepting the default.

Choosing the mode for your application

  • Transparent objects — through-beam, with sensitivity adjusted. Glass and clear film are close to invisible to diffuse sensors.
  • Shiny or polished metal — through-beam. Retro-reflective will miss it.
  • Dark or matt targets — through-beam or retro-reflective. Diffuse ranges collapse on dark surfaces.
  • Dusty environments — through-beam, and specify more range than the geometry needs so there is margin as the lenses foul.
  • Long distances — retro-reflective in M30 reaches 20 metres, the longest in the range.
  • Limited access on one side — retro-reflective or diffuse, since only one side needs wiring.
  • Short-range presence detection with easy access — diffuse, the simplest and cheapest to install.

Specifying with margin

The quoted range is measured under clean conditions with a standard target. In a working plant, lenses accumulate dust and reflectors get knocked. Specify a sensor whose rated range comfortably exceeds the actual distance, so there is headroom to lose before detection becomes marginal.

A 3 metre gap served by a 3 metre sensor will work at commissioning and become intermittent by the second monsoon. A 5 metre sensor on the same gap will not.

Ordering

Send us the distance, the target — material, colour, surface finish, size, whether it is transparent — the environment, whether both sides of the gap are accessible, and the output your controller expects. We will specify the mode and return the part number. Our photoelectric switch range is manufactured in Mumbai, and non-standard cable lengths are available on request.

If the distance is short and the target is metal, an inductive switch from the D30C range will usually be cheaper and more robust — worth checking before defaulting to photoelectric.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

Accent D30C Inductive Proximity Switches: Full Range and Ordering Guide

The D30C is Accent core DC inductive range — M8 to M50, 4 mm to 30 mm sensing, 72 variants. Here is how the ordering code works so you can specify the exact part in one line.

The D30C is the range most Indian plants actually run on: a DC three-wire inductive proximity switch, made in Mumbai to IEC 60947-5-2, in every combination of body size, sensing distance and output that ordinary machine building needs.

There are 72 variants. That sounds like a lot until you understand the ordering code, at which point specifying the exact part you need becomes a single line. This guide explains the code and the four decisions behind it.

Reading the ordering code

A typical part number looks like this:

D30C-1204-NM-3S

It decodes as:

  • D30C — the series: DC inductive proximity switch
  • 12 — body thread, M12
  • 04 — nominal sensing distance, 4 mm
  • N — output transistor type: N for NPN, P for PNP
  • M — contact function: M for normally open (make), B for normally closed (break)
  • 3S — three-wire with short-circuit protection. Plain 3 is the same without protection.

So D30C-5030-PB-3S is an M50 body, 30 mm sensing, PNP, normally closed, three-wire, short-circuit protected. Once the pattern is clear you can write the part number straight onto a requisition.

Decision one: body size and sensing distance

These two are linked. A larger coil senses further, so body size and sensing distance move together across the range:

  • M8 — for tight mechanical spaces, shortest sensing distance
  • M12, 4 mm — the general-purpose small sensor
  • M18, 5 mm and 8 mm — the most widely used size in Indian plants
  • M30, 10 mm and 15 mm — where standoff matters or the target position is less well controlled
  • M36, 20 mm — heavy machinery, larger clearances
  • M50, 30 mm — maximum inductive sensing distance in the range

Two cautions on sensing distance. First, the quoted figure is the nominal distance against a standard mild steel target; the assured operating distance you should design to is shorter. Leave margin. Second, non-ferrous targets reduce the distance — stainless steel, aluminium, brass and copper each by a different factor. Our note on reduction factors for different metals gives the arithmetic. Specifying an M12 4 mm sensor for an aluminium target at 3.5 mm is a fault waiting to happen.

Decision two: NPN or PNP

This is determined by your input card, not by preference. PNP sources current into the input and is the general standard in Europe and increasingly in India. NPN sinks current and is common in Japanese and some Indian-built equipment.

Get it wrong and the sensor appears dead, or appears permanently on. If you are replacing an existing sensor, match what is already there unless you are also changing the input card. Our guide to PNP versus NPN explains how to tell which you have.

Decision three: normally open or normally closed

Normally open (M) is the default: the output switches on when a target is present. Normally closed (B) switches off when a target is present.

The reason to choose NC deliberately is fail-safe behaviour. On a guard interlock or an end-of-travel limit, a normally closed sensor means a broken cable produces the same signal as an unsafe condition, so the machine stops. With normally open, a broken cable looks identical to a healthy sensor with no target, and the machine keeps running. Where the consequence of a missed detection is significant, specify NC.

Decision four: short-circuit protection

The 3S variants include short-circuit protection on the output; the 3 variants do not. The price difference is small and the failure it prevents is common — a crushed cable or a wiring error that shorts the output destroys an unprotected sensor immediately.

Specify 3S unless you have a specific reason not to. The D30C range carries 200 mA and 300 mA output ratings depending on variant; check the load current your solenoid or relay actually draws rather than assuming.

Flush and non-flush mounting

One decision the code does not cover but that matters mechanically: whether the sensor is designed to be mounted flush in metal or must stand proud. Shielded sensors can be embedded in a metal bracket; unshielded sensors sense further but need a clear zone around the face. Mounting an unshielded sensor flush in steel makes it trigger on the bracket. Our note on shielded versus unshielded sensors covers the clearances.

The rest of the range

The D30C covers DC inductive switching. Adjacent needs are served by other series:

  • D32C capacitive — for plastic, liquid, powder, wood and glass
  • D20C NAMUR — for intrinsically safe and hazardous-area duty
  • D31C photoelectric — where the sensing distance exceeds inductive range
  • A20C AC two-wire — for retrofits into panels with no DC supply available
  • Magnetic switches — for sensing through non-ferrous walls

Ordering

If you know the code, send it. If not, send the target material, the sensing distance required, the body size your mounting allows, the output your input card expects, whether the function should be NO or NC, and the supply voltage. We will return the part number and price. Non-standard cable lengths and connector options are available on request — worth asking about on any order above a handful of pieces, because it usually removes a junction box from every machine.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

LVDT Manufacturers in India — and When a Potentiometric Transducer Is the Better Buy

Buyers search for LVDTs because that is the technology they know. For most industrial stroke measurement in India, a potentiometric or Hall-effect transducer is cheaper, more available and entirely adequate.

A lot of linear position enquiries in India arrive asking for an LVDT. Often the application genuinely needs one. Just as often the buyer is asking for an LVDT because that is the technology they encountered first, and a potentiometric or Hall-effect transducer would do the job for less money, with shorter lead times and easier support.

This is a comparison of the three technologies from a purchasing point of view rather than a physics one, so that the enquiry you send matches the problem you have.

LVDT: what it is genuinely good at

A linear variable differential transformer measures displacement through electromagnetic coupling between a primary coil and two secondary coils, with a movable core. Because the core does not touch the coils, there is no wear in the measuring path.

Its real strengths are narrow and worth respecting:

  • Very high resolution over short strokes. Sub-micron measurement is achievable. For metrology, materials testing and precision gauging, nothing else is as appropriate.
  • Effectively infinite mechanical life in the measuring path.
  • Excellent repeatability in a controlled environment.

The costs are equally specific. An LVDT needs AC excitation and signal conditioning electronics, so the installed cost is well above the sensor price. Strokes are typically short. And the whole assembly is more expensive than the alternatives by a margin that is difficult to justify unless you are actually using the resolution.

Potentiometric: the workhorse

A potentiometric transducer is a precision resistive track with a wiper. Apply a voltage across the track and the wiper delivers a voltage proportional to position. It is the simplest possible arrangement and it remains the correct answer for a large share of industrial stroke measurement.

  • Direct DC output with no conditioning electronics required
  • Absolute by nature — position is known at power-up with no homing
  • Long strokes available, well past what LVDTs practically cover
  • Substantially lower installed cost

The trade-off is the wiper. It is a contacting device, so in very high-cycle applications the track eventually wears. In practice, for machine positioning, hydraulic cylinder feedback, valve position and press ram measurement, this is rarely the limiting factor — and Novotechnik conductive plastic elements are considerably more durable than the wirewound potentiometers the objection usually has in mind.

The Novotechnik potentiometric range we supply covers a wide span of formats: TLH side-actuated, LWH, LWG and LWX, the TR and TRS spring-return units, TEX in rod and pivot-head mountings, TE1, TX2, and the PTX sensor kit for integration into a customer housing.

Hall-effect and touchless: the modern middle ground

Magnetic touchless transducers give you the wear-free measuring path of an LVDT without the excitation and conditioning overhead. There is no contact, the output can be a straightforward analogue signal or a digital bus, and protection ratings can be very high because nothing has to penetrate the housing.

For high-cycle industrial applications that do not need sub-micron resolution, this is frequently the correct modern answer, and it is where a lot of applications that would once have used an LVDT now sit.

Choosing between them

Specify an LVDT when you need sub-micron resolution over a short stroke, in metrology, materials testing or precision gauging — and when you have budgeted for the signal conditioning.

Specify potentiometric for general machine positioning, cylinder feedback, valve position and press applications, where you need a reliable absolute reading, a simple DC output and a sensible price. This covers most industrial enquiries.

Specify touchless when cycle counts are high, the environment is hostile, washdown is involved, or you want the position on a fieldbus.

On sourcing LVDTs in India specifically

Worth being direct: we do not manufacture LVDTs, and we would rather say so than sell you something adjacent and call it equivalent. What we do supply is the full Novotechnik linear position transducer range as sole authorised distributor for India and SAARC, covering potentiometric and touchless technologies across a wide range of strokes and mountings.

If your application genuinely requires an LVDT, tell us and we will say so. If it does not — and in our experience most do not — we can usually offer a transducer that is available faster, costs less installed, and needs no signal conditioning.

What to send us

  • Stroke length required, and the mechanical space available
  • Resolution and accuracy genuinely needed, as a number rather than as high
  • Expected cycles per day and the intended service life
  • Output required and the controller it feeds
  • Environment: temperature, protection rating, washdown, vibration
  • Mounting arrangement, and whether a return spring is needed

Our guide to selecting a linear position transducer covers the mechanical decisions in more detail.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com

CANopen Position Sensors: Selection and Supply for Indian Machine Builders

Putting position on the bus removes an analogue input card, its wiring and a calibration step. Which Novotechnik series carry CANopen, what to confirm about profiles, and when analogue is still the better answer.

Machine builders standardising on CAN keep arriving at the same question: can we take position measurement onto the bus rather than running it as analogue into an input card? For most of the Novotechnik range the answer is yes, and the reasons to do it are more practical than they first appear.

What moving position onto CANopen actually saves

An input card and its wiring. Each analogue position signal needs a channel, a screened cable run and a termination. On a machine with six position measurements that is most of a card plus the loom.

The analogue conversion chain. A digital sensor reports position as a number. An analogue one reports a voltage or current that then has to be scaled, and every step in that chain contributes error and drift. Removing it removes a calibration task from commissioning and a drift mechanism from service.

Diagnostics. This is the benefit that justifies the change on its own. An analogue sensor reading mid-scale is indistinguishable from a healthy sensor at mid-position. A bus device reports its own status, so the controller knows the difference between a sensor saying halfway and a sensor that has stopped talking.

Commissioning time. Parameters set over the bus rather than by trimming.

Which series carry CANopen

From the Novotechnik range we distribute in India, CANopen is available on:

Rotary sensors

Linear transducers

Several of these also support IO-Link — MB1-3600, MC1-2800, TF1, TH1 and TP1 — which is worth knowing if your architecture uses IO-Link masters at the machine level rather than CAN throughout.

What to confirm before ordering

Fieldbus variants are configured to the protocol at manufacture. This is not a setting that can be changed on site, so the following need to be right at order stage.

  1. CANopen specifically, not CAN generally. CANopen, J1939 and proprietary CAN implementations all run on the same physical layer and do not interoperate. Confirm which one your controller actually speaks.
  2. The device profile. Encoder devices commonly follow CiA 406. Check your master expects that profile.
  3. Node ID and baud rate setting method. Whether these are set by hardware switch, by configuration over the bus, or fixed at order.
  4. Termination. Whether the sensor includes a terminating resistor or whether you supply it. A bus terminated twice, or not at all, is a classic commissioning fault.
  5. Redundancy. RFX-6900 and RSX-7900 offer redundant measurement channels. If the position feeds a safety function, specify this at the start.
  6. The EDS file. Ask for it with the quotation, not after delivery.

When analogue is still the right answer

Bus is not automatically better. Analogue remains sensible when you need one position signal rather than several, when the controller has a spare analogue input and no CAN master, when you are replacing a single sensor in an existing machine, or when the maintenance team is set up for analogue troubleshooting and not for bus diagnostics. Converting one sensor to CANopen on a machine that is otherwise entirely analogue adds complexity without collecting the benefit.

Where a mixed approach makes sense, several of these series are available in both analogue and bus variants, so the mechanical design can stay identical while the interface differs.

Ordering

Send us the measurement required — angle or stroke — the controller and CAN master you are using, the profile expected, the mechanical arrangement, the protection rating needed, and whether redundancy is required. Accent is the sole authorised Novotechnik distributor for India and SAARC, so configuration questions go back to the factory rather than being guessed at.

Need a price, a drawing or a stock check?

Send us the part number, or just describe the application and the target you need to sense. We will come back with the right model, a dimensional drawing and a quotation. Accent Controls has built sensors in Mumbai since 1985 and is the sole authorised distributor in India and SAARC for Novotechnik (Germany) and Contelec (Switzerland).

Request a quotation  ·  +91 98673 64004  ·  info@accentsensors.com