M12/M18/M30 2-Wire AC Inductive Proximity Sensors

Name: M12/M18/M30 2-Wire AC Inductive Proximity Sensors
Brand: DAIDISIKE
SKU: m12-m18-m30-2-wire-ac-inductive-proximity-sensors
Availability: InStock

Two-wire M12/M18/M30 inductive sensors that wire directly into a 20-250V AC circuit, no DC supply needed.

M12/M18/M30 2-Wire AC Inductive Proximity Sensors - dimensional drawing

🔍 Click to enlarge · 1/7

Technical Specifications

Sensing method	Inductive
Thread sizes	M12, M18, M30
Wiring	2-wire (AC)
Output type	Normally open (A1) / Normally closed (A2)
Mounting style	Flush (P) / Non-flush (T)
Working voltage	20-250V AC
Sensing distance - M12	2mm, 4mm (flush P) / 4mm, 8mm (non-flush T)
Sensing distance - M18	5mm, 8mm (flush P) / 8mm, 16mm (non-flush T)
Sensing distance - M30	10mm, 16mm (flush P) / 8mm, 16mm (non-flush T)
Max load current	400mA
No-load leakage current	<1.8mA
Inrush current	5A for 20ms
Overload current protection point	120mA
Protection rating	IP67
Operating temperature	-25°C to +70°C
Response time	10ms
Switching hysteresis	<15%(Sr)
Repeat accuracy	<5%(Sr)
Temperature drift	<10%(Sr)
Voltage drop	<8VAC at 400mA
Switching frequency	<25Hz
LED indicator	Yes
Cable length	2m standard (extendable on request)

Overview

This is a family of inductive proximity sensors in M12, M18 and M30 threaded metal housings, wired with only two leads (brown BN and blue BU) that are inserted in series with an AC load — the sensor itself does not need a separate power terminal. Each size is available in flush (P, embeddable in metal) and non-flush (T, needs metal-free clearance around the head) mounting styles, and in normally-open (A1) or normally-closed (A2) output logic.

It suits OEM machine builders, panel retrofitters, and maintenance engineers working on equipment where the control circuit is AC-powered (e.g., older relay/contactor panels, AC solenoid/lamp circuits) and a DC 2-wire or 3-wire sensor would require an extra power-conversion or interface step. Working voltage spans 20-250V AC, with sensing distances from 2mm up to 16mm across the three thread sizes.

Features & Benefits

Direct AC line connection, no DC power supply needed

Wires directly in series with a 20-250V AC load using only 2 leads (BN/BU), eliminating the need for a separate DC power supply, transformer, or interface relay in AC-controlled panels.

Wide sensing-distance lineup across three thread sizes

Sensing distances span 2mm (M12 flush) up to 16mm (M18/M30 non-flush), giving 24 model variants across NO/NC outputs to match different target sizes and mounting clearances.

Both flush and non-flush mounting options

Flush (P) versions can be embedded flush with surrounding metal, while non-flush (T) versions offer longer sensing distance where metal-free clearance is available around the sensing face.

NO/NC output selection built into the part number

A1 suffix denotes AC normally-open output, A2 denotes AC normally-closed output, letting engineers directly match existing relay logic without adding a signal-inverting relay.

IP67-rated sealed metal housing

Rated IP67, suitable for environments with dust, splashing water, or washdown exposure typical of production-line mounting locations.

Built-in overload current protection

The sensor's overload current protection point is specified at 120mA, giving the switching circuit a defined protection threshold.

Onboard LED status indication

Every model in this AC series includes an LED, giving a visual on/off status indication at the sensor without needing to trace back to the control panel.

2m standard cable, extendable on request

Ships with a 2-meter lead cable as standard, with longer lengths available for custom orders.

Applications

Workpiece-in-fixture presence detection — Detects whether a metal workpiece is present in a fixture or nest station on an assembly/indexing line.

Rotary-table position / index detection — Confirms rotary indexing-table position by sensing metal features on the table as it stops at each station, supporting stop-position confirmation in rotary assembly cells.

Aluminum can / metal container detection on a conveyor line — Side-mounted sensing of metal cans passing on a belt conveyor for counting, gating, or line-speed synchronization.

Pallet / carrier positioning on conveyor lines — Detects the metal frame of a pallet or carrier fixture to confirm it has reached a stop or transfer position on a chain/roller conveyor.

Door open/closed status detection on machine guarding or enclosures — Senses the metal door frame/hinge structure to report open vs. closed status, useful for interlocked machine access panels wired into an existing AC control circuit.

Retrofit of AC relay/contactor control panels — Because the sensor wires directly into the existing AC loop, it is well suited to replacing worn mechanical limit switches in panels that were never built with a DC sensor supply.

AC-driven indicator lamp or solenoid interlock circuits — The 2-wire AC output can switch directly in series with an AC pilot lamp or small AC solenoid coil circuit without an intermediate relay, subject to the load current staying within the rated range.

Models & Ordering Information

M12

M1202A1PM1202A2PM1204A1PM1204A2PM1204A1TM1204A2TM1208A1TM1208A2T

Flush (P): 2mm, 4mm. Non-flush (T): 4mm, 8mm.

M18

M1805A1PM1805A2PM1808A1PM1808A2PM1808A1TM1808A2TM1816A1TM1816A2T

Flush (P): 5mm, 8mm. Non-flush (T): 8mm, 16mm.

M30

M3010A1PM3010A2PM3016A1PM3016A2PM3008A1TM3008A2TM3016A1TM3016A2T

Flush (P): 10mm, 16mm. Non-flush (T): 8mm, 16mm.

How to Select

Step 1 - Choose thread size by installation space: M12 (compact, tightest mounting clearance), M18 (mid-size), or M30 (largest body, longest available sensing distance).
Step 2 - Choose sensing distance (Sn) needed for your target: M12 offers 2mm/4mm (flush) or 4mm/8mm (non-flush); M18 offers 5mm/8mm (flush) or 8mm/16mm (non-flush); M30 offers 10mm/16mm (flush) or 8mm/16mm (non-flush).
Step 3 - Choose mounting style: Flush (P suffix) if the sensor will be embedded level with surrounding metal (e.g., in a metal bracket or machine frame); Non-flush (T suffix) if the sensing face needs to protrude with clearance for maximum range.
Step 4 - Choose output logic (NO/NC): A1 suffix = AC normally-open (contact closes on target detection); A2 suffix = AC normally-closed (contact opens on target detection). Match this to your existing control-circuit logic (e.g., fail-safe stop circuits typically prefer normally-closed).
Step 5 - Confirm AC electrical compatibility: Working voltage range is 20-250V AC, max load current 400mA, with a no-load/leakage current under 1.8mA - check that your load (relay coil, PLC AC input, lamp, etc.) draws enough current to keep the sensor's internal circuit powered and does not exceed 400mA.
Reference part number example: M1808A1T = M18 body, 8mm sensing distance, A1 (AC normally-open), T (non-flush).

📘 Need the full method? How to Choose a Proximity Sensor · NPN vs PNP Sensor Outputs Explained

When NOT to specify the M12/M18/M30 — and what to use instead

Detecting non-metallic targets such as plastic, wood, liquid, or glass

Why not: This is an inductive sensing family - it only responds to metal targets, per the sensing-method spec; it has no dielectric-based detection capability for non-metallic materials.

Use instead: A capacitive proximity sensor, such as the M12/M18/M30 metal-housing capacitive proximity sensor series, which responds to non-metallic and liquid targets.

Wiring the sensor into a DC-powered PLC input or control circuit

Why not: This is a 2-wire AC-only device rated 20-250V AC on its brown/blue leads; it has no DC operating-voltage rating and is not designed to be driven by a DC supply.

Use instead: A 3-wire DC inductive proximity sensor, such as the M18/M30 inductive proximity sensor series, for DC-powered control circuits.

Driving a very low-current relay coil, PLC input, or other high-impedance AC load

Why not: As a 2-wire AC sensor, the load current itself keeps the sensor's internal circuit powered; the datasheet gives a no-load leakage current below 1.8mA but does not publish the minimum load current the sensor needs to operate reliably, so an undersized high-impedance load risks nuisance-triggering or the sensor failing to switch off cleanly.

Use instead: Confirm the minimum required load current with the factory, or use a DC 3-wire sensor with its own dedicated power feed instead of load-powered operation.

High-speed applications needing switching frequencies above the rated 25Hz, such as fast part counting

Why not: Switching frequency for this AC series is specified at <25Hz and response time at 10ms, both slower than the DC 3-wire inductive families in this catalog.

Use instead: A DC 3-wire inductive proximity sensor, such as the M18/M30 inductive proximity sensor series, which is rated from 0.2ms to 2ms response depending on model.

Safety-related guarding or personnel-protection interlocks

Why not: No safety rating or safety-standard compliance is claimed anywhere in this product's specifications.

Use instead: A dedicated safety interlock switch or safety light curtain (DX series), not a standard proximity sensor.

Specifications we do not publish yet

We only publish a figure once we are confident it is true. The items below are still being validated through further testing and real-world customer feedback, so for now we would rather leave them open than guess. If one of them matters to your design, ask us for the latest validated status.

Non-ferrous metal (aluminum/brass/stainless) sensing-distance correction factor
Minimum load current required to keep the sensor's internal circuit reliably powered
Housing material composition (e.g., brass, stainless steel)
MTBF / rated mechanical and electrical life
Cable conductor gauge and jacket material for the standard 2m cable
Certification marks (CE, UL, etc.)
Tolerance band on the rated 2-16mm sensing distances (e.g., ±10%)

Frequently Asked Questions

Does this sensor need a separate DC power supply?

No. This is a 2-wire AC sensor - it is wired in series directly with a 20-250V AC load circuit, using only its brown (BN) and blue (BU) leads. It does not have a dedicated power terminal.

What is the difference between the A1 and A2 suffix in the part number?

A1 denotes an AC normally-open (NO) output - the switch closes when a metal target is detected. A2 denotes an AC normally-closed (NC) output - the switch opens when a metal target is detected.

What is the difference between the P and T suffix?

P denotes flush (embeddable) mounting, where the sensor body can be installed level with surrounding metal. T denotes non-flush mounting, which requires a metal-free clearance zone around the sensing face and typically allows a longer sensing distance for the same body size.

What sensing distances are available in this AC series?

M12: 2mm/4mm (flush) or 4mm/8mm (non-flush). M18: 5mm/8mm (flush) or 8mm/16mm (non-flush). M30: 10mm/16mm (flush) or 8mm/16mm (non-flush).

What is the working voltage and maximum load current?

Working voltage is 20-250V AC, maximum load current is 400mA, with a rated inrush current of 5A for 20ms and a no-load/leakage current of under 1.8mA.

What is the protection rating and operating temperature range?

The sensor is rated IP67 and specified for an operating temperature range of -25°C to +70°C.

Does the sensor have short-circuit or overload protection?

An overload current protection point of 120mA is specified in the datasheet; short-circuit protection is not indicated for this AC series. Certification documents are available on request.

Is there a visual status indicator on the sensor?

Yes, every model in this AC series includes a built-in LED for on-site on/off status indication.

What cable length is standard, and can it be customized?

The standard cable length is 2 meters; longer lengths are available on custom order per the datasheet.

What wire colors are used, and what do they connect to?

Brown (BN) and blue (BU) are the two leads used in this AC 2-wire configuration; both are wired in series with the AC load (~), per the sensor's internal switch (NO or NC contact type depending on model).