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Thiim BMWB DC Combined Over And/Or Under Voltage Relay


  • Includes two relays for use in parallel or for individual under and over voltage signalisation
  • Accurate adjustment for upper limit, upper return, lower limit and lower return by means of multiturn potentiometers
  • Easy dipswitch setting selects function as under and over voltage relay, window relay or under or over voltage relay only
  • LEDs indicate the state of the input
  • LED indicates the state of the relay
  • LEDs indicate when the timing function is active


BMWB is a combined over and/or under voltage relay. The voltage relay is designed for precise monitoring of a wide range of DC voltages from 14V to 340V. With a build in high efficiency switch mode power supply, the BMWB is able to cover the whole measuring range without the need of an external supply. The BMWB can by means of dipswitches be set to work as a relay for monitoring under voltage and over voltage with two individual C/O contacts, or the contacts can be paralleled and the BMWB be used as a window discriminator relay where both C/O contacts are in the powerless position outside the window. With the paralleled relays the BMWB can be set to only register under or over voltage.

When the supply voltage is applied, the - power up reset - period begins. If a voltage within the allowed voltage range is applied to the input, the internal relay pulls in at the end of the reset period. If the input voltage exceeds the adjusted upper or lower limit, the corresponding relay or both relays drops out. If the input voltage comes between the upper return and the lower return, the relay pulls in. As under voltage relay only, the relays remains energized for input voltages exceeding the upper limit. As over voltage relay only, the relay remains energized for input voltage under the lower range limit, until it drops out due to power loss at inputs below 14V.

Voltage monitoring in UPS, stationary and mobile battery installations.

Additional Information

Manufacturer Thiim


Product Name / Options Price (ex VAT)
Thiim BMWB-1434-DA3C DC Voltage Monitoring Ring Relay, Rail Mounting - 14 V - 340 V DC - 41651 Call for Prices

Thiim BMWB-1434-DE3C DC Voltage Monitoring Ring Relay, Socket Mounting - 14 V - 340 V DC - 44250 Call for Prices