DC Voltage Detector S631


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  • Optical high side isolation
  • Polarity protected
  • Automatic reset
  • 10A rated relay contacts
  • Shock and vibration suited for rail applications

Product Description

Model S631 DC Voltage Level Detector provides an effective and accurate solution to monitor DC voltage. The unit detects the applicable high voltage and upon reaching the calibrated threshold, the internal relay changes state (relay engages – closes). Optical isolation guarantees safe operation and the high accuracy reference provides an accurate and repeatable trip point.

The S631 Series is calibrated at the factory to 375Vdc and capable of withstanding a continuous overload of 1000Vdc and a 2000Vdc transient (25m-sec), without damage or performance deterioration.  The detector delivers performance accuracy over a temperature range of -25°C to +75°C and operates with a supply voltage from +25Vdc to +45Vdc.  The unit’s molded construction and internal epoxy encapsulation creates a durable transducer, withstanding environments of moisture, humidity, vibration and shock.

The S631 DC Voltage Detector comes standard with terminal studs for easy quick connection and are reverse polarity protected.

  • Rail applications
  • Traction motor control

Additional information

Weight 20 oz
Dimensions 3 × 3 × 2 in




Supply Type

Supply Voltage

Housing Material

Voltage Range


  • Attitude: Works in any position.