Capacitive · M8 – M30, non-metal detection

Capacitive Proximity Sensors (M8 – M30, 1 – 30 mm)

Detects what an inductive sensor cannot: plastic, glass, wood, grain, water and powder, up to 30 mm from an M30 body.

Model LJ8M-E1N / LJ8C-E2N / LJ12M-E3N / LJ12C-E6N / LJ18M-S8N / LJ18C-S15N / LJ30M-S20N / LJ30C-S30N · Brand LE Raun · Category: Proximity Sensors

BodyM8 – M30

Sensing1 – 30 mm adj.

TargetNon-metal

Frequency50 – 100 Hz

Request a quote Full specifications

Overview

A capacitive sensor is an inductive sensor with a bigger, unshielded electrode: it responds to any material with a dielectric constant above air, which covers plastic, glass, wood, grain, water and most powders. That makes it the fallback whenever a photoelectric sensor cannot see the target (transparent, matte, dusty) and an inductive sensor cannot either (non-metal).The cost is stability. Humidity, a film of product on the face and the dielectric constant of the material all shift the trip point, which is why every version above M8 has an adjustable setting distance — set it deliberately low and the drift stays inside the margin.Bodies run M8 to M30, sensing 1 mm to 30 mm, at 50 – 100 Hz with a 1.5 ms response. All are 10 – 30 V DC with NPN or PNP, NO or NC output.

Application scenarios

Bottle and container presence on a filling line

M18 non-flush at 15 mm detects a PET bottle without touching it, from behind the guide rail.

Granulate and powder level in a hopper

M30 body through a plastic hopper wall reports high level; the 20 mm range means it never contacts the product.

Coolant and oil level in a tank

M30 flush body through a 3 mm tank wall detects the liquid level without a float switch.

Timber and board presence on a saw infeed

M30 at 30 mm sees a 20 mm board arriving, in a dusty environment where a photoelectric sensor would not last.

Glass sheet detection at a cutting table

M18 non-flush at 15 mm detects the glass edge where an inductive sensor is blind.

Industries

Food and beverage
Packaging
Woodworking
Chemical processing

Technical specifications

Series	LJ8M-E1N · LJ8C-E2N · LJ12M-E3N · LJ12C-E6N · LJ18M-S8N · LJ18C-S15N · LJ30M-S20N · LJ30C-S30N
Body sizes	M8×45 · M12×60 / 65 · M18×70 / 78 · M30×86 / 87 mm
Sensing distance	1 – 30 mm, adjustable on all but the M8 versions
Housing / face	Stainless steel (M8), nickel-plated copper (M12 – M30); PBT face
Operating voltage	10 – 30 V DC
Switching frequency	100 Hz (M8) · 50 Hz (M12 – M30)
Response time	1.5 ms
Repeat accuracy	< 5.0 % (Sr)
Ambient temperature	−25 °C – +70 °C
Output	NPN / PNP, NO / NC — N, N2, P, P2 suffix
Protection	IP67
Current consumption	≤10 mA
Output current	≤200 mA
Voltage drop	≤1.5 V
Hysteresis	≤0.05 mm of the sensing distance
Circuit protection	Short-circuit, overload, reverse polarity
Cable	2 m PVC, 3 × 0.2 mm², oil-resistant

Dimensions

Item	Value
Thread	M12 × 1 · M18 × 1 · M30 × 1.5
Cable	Ø4 mm on M12 · Ø5 mm on M18 and M30
Adjustment	Potentiometer under the rear cap on the shielded types

A capacitive body needs a clear zone in front equal to the sensing distance: mounting it through a metal plate without that clearance makes it switch on the plate.

Wiring & output

Lead	Colour
2	Blue
3	Black
—	Two-wire types

How to specify

01
Choose shielded or unshielded
A shielded (flush) sensor can be embedded in metal with only its face exposed, at about 60 % of the unshielded range. An unshielded sensor needs a free zone around the barrel but reaches further.
02
Size the sensing distance
Order at least 1.5 × the nominal distance to allow for tolerances, temperature and target material. Non-ferrous targets — brass, aluminium, copper, stainless — reduce the distance to roughly 30–50 %.
03
Match the target size
The target should be at least as large as the sensing face. A smaller target reduces the distance proportionally, so a 4 mm target on an M18 sensor will not switch at 5 mm.
04
Pick the output and the body
NPN / PNP, NO / NC, 3-wire or 2-wire. Plastic barrel for general use, stainless for weld fields, PTFE-faced for weld spatter, high-temperature types up to 120 °C.

Why this series

Senses dielectrics, not just metal

Plastic bottles, glass, timber, grain, coolant and powder all change the field. That is the whole reason this family exists.

Adjustable 1 – 30 mm

The pot lets you set the trip point so a 0.5 mm film on a conveyor does not trigger it but the 20 mm block behind it does.

Flush and non-flush at every size

The C bodies are non-flush and reach further; the M bodies sit level in a metal fixture.

Slower by nature

50 – 100 Hz is enough for a level or a part on a conveyor, and the lower frequency is what keeps the field stable.

Questions

Will it detect water through a plastic tank wall?

Yes, up to the wall thickness the range allows. A 3 mm HDPE wall with an M30 at 20 mm works; a 10 mm wall does not. Tell us the wall material and thickness and we will confirm.

Why does the output stay on after the part leaves?

Product build-up on the face. Capacitive sensors sense through a film, so a crust looks like a target — clean the face or fit the flush version so it wipes itself.

Can it distinguish plastic from metal?

No. It detects both. If you need to separate them, use an inductive sensor for the metal and a capacitive one for the rest.

Need a quotation for Capacitive Proximity?

Send your application details or the guard opening dimensions and we will specify the right model and configuration for your machine.