Accent D30C Inductive Proximity Switches: Full Range and Ordering Guide

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.