UB A400 relay – Voltage monitoring


The voltage monitoring relay UB A400 opens auxiliary loads circuits when battery voltage becomes too low and puts them back in service when battery voltage recovers. A time delay of 20 seconds engages before opening a load circuit and a time delay of 2 seconds before putting back in service a load.
The plug-in design offers secure locking feature for maximum ease of maintenance (no wires need to be disconnected or other hardware removed for relay inspection or replacement). The resistance to impact and vibration is conform to standards in force for Railway Transported Equipment.
Positive mechanical keying of relay to socket is built into relay and socket during manufacture and terminal identifications are clearly marked on identification plate that is permanently attached to the relay.
The UB A400 relay is pluggable in the following sockets: EA 102 B, EA 102 BF, EA 103 BF, EA 104 B, EA 104 BF, EA 105 BF, EA 112 BF.


The UB A400 relay is designed for voltage level sensing and used for example to monitor the battery load shedding.


  • Load shedding relay – 1 voltage level
  • 4 C/O contacts, form Z, 5 A resistive
  • Plug-in design with secure locking feature for maximum ease of maintenance
  • -40 °C…+85 °C operating temperature


  • Proven reliable
  • Long life cycle
  • Easy to maintain and replace
  • Low life cycle cost
  • No maintenance

Railway compliancy

  • NF F 62-002 Rolling stock – Instantaneous relays contacts and sockets
  • NF F 16-101/102 Fire behaviour – Railway rolling stock
  • EN 50155 Railway application – Electronic equipment used on rolling stock
  • IEC 61373 Railway application – shock and vibration tests




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