The 3-wire DC inductive sensor is the workhorse of factory automation: separate brown, blue and black conductors for supply positive, supply negative and switched output. Available as PNP (sourcing) or NPN (sinking), in normally open or normally closed logic.
Choosing PNP or NPN
PNP sensors switch the positive line to the load and are the default across most Indian and European PLC installations. NPN sensors switch the negative line and are common on Japanese-origin machinery and older imported equipment. Match the sensor to your PLC's input card — a sinking input card needs a PNP sensor, and a sourcing input card needs an NPN sensor.
Normally open (NO) outputs turn on when metal enters the field; normally closed (NC) outputs turn off. Safety and fault-detection circuits usually prefer NC, so a broken cable fails to the safe state.
Key features
- PNP or NPN output — specify at order to match your PLC input card.
- NO or NC logic — adaptable to any control philosophy.
- No voltage drop on the load — separate supply and output conductors.
- IP68 chrome-plated brass — rated for coolant and wash-down duty.
- Short-circuit and reverse-polarity protection built in.
- LED status indicator for fast commissioning and fault-finding.
Technical specifications
| Parameter | Value |
|---|---|
| Wiring | 3-wire DC (brown +, blue −, black output) |
| Output type | PNP (sourcing) or NPN (sinking) |
| Output function | Normally open (NO) or normally closed (NC) |
| Rated switching distance | 1 mm to 50 mm, depending on barrel size |
| Hysteresis | 5–10% of the rated sensing distance |
| Repeatability | 5–10% of the rated sensing distance |
| Operating voltage | 10–30 V DC |
| Switching frequency | Up to 200 Hz |
| Housing material | Chrome-plated brass (stainless steel on request) |
| Protection class | IP68 — dust-tight and submersion-proof |
| Mounting | Flush (shielded) or non-flush (unshielded) |
| Protection circuits | Short-circuit and reverse-polarity protected |
| Status indication | LED on the sensor body |
| Standard cable | 2 m, 3-core PVC (custom lengths on request) |
| Available sizes | M8, M12, M18, M30, M50, M80 and rectangular |
Typical applications
- Conveyor and material-handling systems — part counting and jam detection.
- Manufacturing lines — part-presence verification and assembly interlocks.
- Process control — valve and actuator position feedback.
- Machine tools — turret indexing, slide position, guard confirmation.
How to order
Tell us the sensing gap, the target material, your supply voltage and the output type your controller needs. If you are replacing an existing sensor, a photograph of the body markings is usually enough for us to identify an equivalent. We will confirm the specification and quote — normally the same day.
Related products
Frequently asked questions
Should I order PNP or NPN?
Order PNP if your PLC has sinking (negative-common) input cards — this covers most Siemens, Allen-Bradley, Delta and Mitsubishi installations sold in India today. Order NPN if your input card is sourcing (positive-common), which is common on older Japanese machinery. If you are unsure, send us the PLC model number.
What sensing distance can I expect?
It depends on barrel size and whether the sensor is shielded. Typical rated distances are 2 mm for M8, 4 mm for M12, 8 mm for M18, 15 mm for M30, 25 mm for M50 and up to 50 mm for M80. These figures are for mild steel; stainless steel, aluminium and brass targets reduce the range.
Can I mount the sensor flush in a metal plate?
Only if you order the shielded (flush-mountable) version. An unshielded sensor mounted flush in metal will latch on permanently. Unshielded types need a clear zone of free space around the sensing face.
Need a quote for the 3-Wire DC Proximity Sensor (PNP / NPN)?
Send us your application — target material, sensing distance, supply voltage and housing constraint. We will recommend a part, quote it, and ship from Mumbai.