HEYI Inductive Proximity Sensor LJ12A3


Advantage :

  1. Compact volume, Diversified exterior
  2. High precision of repeated location
  3. Good performance of anti-interference
  4. High on-off frequency, Wide voltage range
  5. Dust proof, vibration proof, water proof and oil proof
  6. With short-circuit protection and inverted connecting protection


Flush : DC6 ~36V, AC 90 ~250V

Detection distance

  • DC6 ~36V
  • NPN: NO, NC, NO+NC
  • PNP : NO, NC, NO+NC
  • two wire system: NO, NC

MODEL : 2mm

  • LJ12A3-2-Z/BX / LM12-3002NA
  • LJ12A3-2-Z/AX / LM12-3002NB
  • LJ12A3-2-Z/CX / LM12-3002NC
  • LJ12A3-2-Z/BY / LM12-3002PA
  • LJ12A3-2-Z/AY / LM12-3002PB
  • LJ12A3-2-Z/CY / LM12-3002PC
  • LJ12A3-2-Z/EX / LM12-3002LA

AC 90 ~250V

RC Control Label Silicon :  NO, NC, NO+NC

Relay output

MODEL : 2mm

  • LJ12A3-2-J/EZ / LM12-2002A
  • LJ12A3-2-J/DZ / LM12-2002B

Detection distance

  • Non-flush

DC6 ~ 36V

  • NPN: NO, NC, NO+NC
  • PNP : NO, NC, NO+NC
  • two wire system: NO, NC

MODEL : 4mm

  • LJ12A3-4-Z/BX / LM12-3004NA
  • LJ12A3-4-Z/AX / LM12-3004NB
  • LJ12A3-4-Z/CX / LM12-3004NC
  • LJ12A3-4-Z/BY / LM12-3004PA
  • LJ12A3-4-Z/AY / LM12-3004PB
  • LJ12A3-4-Z/CY / LM12-3004PC
  • LJ12A3-4-Z/EX / LM12-3004LA
  • LJ12A3-4-Z/DX / LM12-3004LB


  • RC Control Label Silicon :  NO, NC, NO+NC
  • Relay output

MODEL : 4mm

  • LJ12A3-4-J/EZ / LM12-2004A
  • LJ12A3-4-J/DZ / LM12-2004B
  • Control output : DC 200mA
  • SCR/Relay 300mA
  • Output voltage drop DC/AC : DC<2V DC(Two wire system) <3.9V AC<10V
  • Consumption current :  DC<15mA AC<10mA
  • Standard detected object : 15×15×1(A3 iron)
  • Repeated precision :  0.01
  • DC/AC Response frequency : 400Hz/25Hz
  • Working environment temperature : –25°C~75°C
  • Insulation resistance : ≥50MΩ
  • Shell material : Metal
  • Protection grade :  IEC standard IP67
  • Altemative model at home and abroad :  E2E-X5M□

Series connection and parallel connection:

Explanation of technical terms:
Detection distance

Move the detected object according to assigned method, the distance from the reference position (reference
plane)to the detecting action(resetting)

Setting distance

Including the effects like temperature  and voltage, without error action the distance passed through from the
practical detection surface to the objected object.

Standard detected object

Take as standard detected object to detect the basic performance. the shape, size and material have been

Differential distance

The absolute value of the distance difference between the distance to action and the distance To resetting

Response time

  • TI: when the objected object enters the action zone, the time from proximity sensor being in action state to
    output appearance.
  • T2:the time from leaving actionzone to output disappearance.

Response frequency

Work out the tracking output times per  second by repeatedly approaching the detected object Brief detection method sees the above diagram

Main features:

Take high frequency oscillation type proximity sensor(front detector)as representative example to briefly explain general features of proximity switch.

Item Explanation Features

  • About detected object
    When the material of detected object is non magnetic metal, the distance of action should descend. But when
    the foil material is approximately thicker than a.01mm,the detection distance will be the same as that of
    magnetic object If the film plating is extremely thin or non-conductive, detection cannot be conducted. The
    effect of cladding material, take note of the changing of detection distance.
  • About ambient weather
    In order to maintain reliable action and long service life, please avoid the(outdoor)occasion beyond the
    stipulated ambient temperature. Do not drench it with Water or water- soluble cutting lubricant when it is used with cover, although the proximity sensor is waterproof. Do not used in the occasions with chemical agents, especially strong base acid, nitric acid, hot strong sulfuric acid and so on.
  • About maintenance and overhaul
    • In order to keep the proximity sensor to work stably for long time, the following regular examinations should be performed just like general control.
    • Check the installation position of detected object and proximity sensor if any deviation, loosening or
      deformation exists.
    •  Check the attached wires and connecting parts if any loosening bad contact or wire breaking off exists
    • Check if there is any metallic powder accumulation or not
    • Check if the temperature condition and surrounding environment condition are normal or not
    • Check if the detection distance is normal or not

The size of detected object and detection distance If the detected object is square metal sheet with constant  hickness (t=1mm), detect at detection distance X when change its side length dmm. X(mm)

When the detected object is bigger than standard detection distance is constant. According to different Machine type, sometimes the features will that mentioned on the left. To through type, the detection object is like cylinder metal bar

The thickness of detected object and detection distance Detect at detection distance Xmm(front detector)when change the thickness of the assigned standard detected object 1mm.

For more than 1mm thick magnetic metal like iron on the main, the detection distance will not change.

The effects resulted from the Thickness of detected object and cladding material Because the detection to standard
detected object will be effected by its shape, size, material, and various cladding material, confirm through detection distance Xmm measurement.

The effects resulted from detection distance and cladding material of the metal excluded iron will be different according to different machine type On the main, the machine type which detects all the metals will not be effected by cladding material.

Correct use, installation and cautions:

  • Mounting screw switch
  • Do not tighten with over-torque when mounting the switch. Adopt toothed washer when tightening
  • Mounting non screw type pillar switch
  • When adopt adjusting screw, the tightening torque should be within 2-4kgf-cm
  • Protection against the interference of non detected object
  • hen mounting the proximity switch on the metal part, do refer to the following diagram. Remain a certain space in advance according to the shown diagram so as to prevent the switch from error action
  • Protection against mutual interference between switches
  • Mount according to the size which is bigger than that in the following diagram to prevent the switch from error action resulted from mutual interference if mount the switches contra-positively or in parallel
  • Adjustable switch action distance(sensitivity)
  • The action distance(sensitivity)of proximity switch can be adjusted by the means of trimming potentiometer. Increase the action distance and reduce sensitivity when turn clockwise. Vice versa. Do not use in the critical state of max. action distance.
  • Guard of switch lead-wire
  • When mount switch, fix the lead-wire at a distance about 10cm from the switch with wire clip so as to prevent the switch lead-wire from damage from outer force

■ Cautions

  • DC switch should adopt insulation transformer and ensure stable voltage mains corrugation.
  • IF any electric power line or dynamic line passes through the surrounding of switch lead-wire, in order to prevent the switch from damage or error action, cover the metal bushing on the switch lead-wire and ground it to the earth
  • Set the switch use distance within the rated distance to avoid the effects from temperature and voltage
  • Wiring while power-on is strictly prohibited. Connecting the wires strictly according to the wiring diagram and output return elementary diagram.
  • If there are any special requirements to the switch like water proof, oil proof, acid proof, base proof, high temperature proof or with any other specifications, the users are required to give clear indication when placing an order. We can produce according to the requirements of the use.

Application illustration of proximity