Obsolete Railway Relays

ACD-U200 Battery voltage monitoring relay


This product is no longer available. The replacement relay is the MTDV4-U200.
Click here to go to the product page of the MTDV4-U200.


Electronic plug-in railway monitoring relay for battery voltages. The relay reacts on the mean value of a DC-voltage with ripple. The pull-in voltage and hysteresis (the difference between pull-in voltage and drop-out voltage) are adjustable by means of multiturn trim potentiometers.
The pull-in time after crossing the setpoint is < 15ms. The drop-out time is approximately 20 ms, which can be extended to 250 ms. Optional the relay can be supplied with fixed (sealed) set values, or led indication. The ACD relays are pluggable into standard D-U200 relay sockets.



  • Plug-in DC voltage monitoring relay
  • Adjustable pull-in voltage and hysteresis (with a multi-turn potentiometer)
  • 1 CO and 1 NO contact (weld no transfer)
  • Compact plug-in design
  • Flat, square silver plated relay pins for excellent socket connection
  • Wide range sockets
  • Integrated snap lock
  • Transparent cover
  • Flexibility by many options


  • Proven reliable
  • Long-term availability
  • Easy to maintain
  • Used in safety-critical applications
  • Low life cycle cost
  • No maintenance

Railway compliancy

  • EN 50155 Electronic equipment used on rolling stock for railway applications
  • IEC 60571 Electronic equipment used on railway vehicles
  • IEC 60077 Electrical equipment for rolling stock in railway applications
  • IEC 60947 Low voltage switchgear and control gear
  • IEC 61373 Rolling stock equipment - Shock and vibration test
  • EN 50121 Electromagnetic compatibility for railway applications
  • NF F16-101/102, TS 45545-2 Fire behavior - Railway rolling stock
  • IEC 60529 European standard describes the protection class (IP-code)
  • IEC 60068-2

Product information request

Railway rolling stock
Railway signalling