WDA Motion Alignment Sensor

Belt or Chain Alignment and Motion Monitor


Non-contacting extended range magnetic proximity sensor, not affected by dust or material build up, used to detect moving ferrous material up to 100mm away from the sensor. The WDA sensor can be used on bucket elevators to measure speed and alignment by sensing either the metal elevator buckets, or the ferrous bolts attached to plastic buckets. A more specialized use for the WDA switch is as a broken/slack chain detector on drag chain conveyors, or as a non-contact speed switch for screw conveyors. The sensor is used in conjunction with a PLC or with 4B's Watchdog™ Elite or A400 Elite control units. Two output signals are provided: one signal is a pulse output, representing each bucket detected: the second signal is a continuous output when moving buckets are detected.

WDA sensor - belt speed / alignment / chain break sensor
Product Features: 
  • Magnetic Proximity Belt Speed and Belt Alignment Sensor
  • Detects Moving Steel Ferrous Targets
  • Adjustable Sensing Range of 25 – 75mm
  • Not Affected by Material Build Up
  • Stainless Steel Construction
  • High Temperature Version Available
Electronics Application: 

Note: The WDA is Available in Two Models (Standard & High Temp.).

Part numbers & Accessories:

  • WDA3V34CAI  - WDA Standard Sensor
  • HTAS1V34 WDA -  High Temperature Sensor
  • WDAMB  - Sensor Mount (Included with Sensor)
  • AS62  - Abrasion Shield



Supply Voltage12-24VDC12-24VDC
Supply Current65mA130mA
Detection Range25-75mm25-75mm
Detection Rate20-2000 Targets/Min20-2000 Targets/Minute
Outputs(Max)100mA Sink; 50mA Source100mA Sink; 1mA Source
ATEX and IECEXZone 20Not Approved
CSAClass II Div 1Not Approved
Temperature Rating-20°C to +50°C-29°C to +150°C Continuous
Dimensions50mm DIA x 150mm length50mm DIA x 150mm length



Watchdog Super Elite hazard monitor (WDC4)
Combined belt speed (slip), belt alignment, continuous bearing temperature, pulley alignment and plug condition monitor for bucket elevators and conveyors.

  The WDA sensor will not calibrate, what is the issue?  
Make sure that the orange wire is connected correctly, this powers the potentiometer (calibration screw).   

  Why will the LED on the back of the sensor not turn on?  
  Check to see that there are no objects stuck to the face of the sensor (washer, bolts, etc.). Due to the magnetic pull on the face of the sensor, objects can stick and interfere with the sensor. 
  What if the best sensing depth of the WDA sensor?  
The WDA sensor can detect ferrous targets from 1 to 3 inches away.  Keep in mind the distance of other objects within the sensing area. For example, a belt splice on a bucket elevator may be longer than the intended target and can interfere or hit the WDA sensor.

Speed Switch Demonstration Video