DC Voltage Monitoring Relay

DC voltage monitoring relay is applied in the DC circuit for monitoring undervoltage and overvoltage of DC cabinet, battery, electric control system, etc. ATO company provides DC voltage monitoring relay with 2 C/O contacts (2 Form C or DPDT) provide protection for the equipment from undervoltage and overvoltage in DC circuit 12V, 24V, 36V or 48V, adjustable trip delay time, LED indicator for working state. DIN rail mounting, compact design, high precision and factory price. In addition to wholesale, ATO as a vendor can also customize the monitoring relay you want.
DC voltage monitoring relay


  1. Compact size in DIN rail mounting.
  2. DC circuit monitoring of overvoltage and undervoltage. Single phase voltage monitoring relay also can do it.
  3. Adjustable overvoltage and undervoltage threshold.
  4. Adjustable trip delay time.
  5. Powered by the measuring circuit.
  6. Monitoring relay with 2 C/O contacts. (2 Form C or DPDT)
  7. 2 LEDs for status indication.


Measuring Circuit DC circuit
Monitoring Functions Overvoltage, Undervoltage
Rated Voltage DC 12V DC 24V DC 36V DC 48V
Voltage Setting Range Undervoltage 10-14V 20-28V 30-42V 40-56V
Overvoltage 13-17V 26-34V 39-51V 52-68V
Trip Delay Time 0.1-15s adjustable
Voltage Hysteresis 3-5% fixed
Indicators LED indicators for Normal, Trip
Output Contacts 2 C/O
Contact Capacity 6A, 250V AC (resistive load)
Degree of Protection IP 20
Working Conditions Operating Temperature -25℃~65℃
Humidity ≤85%RH, non-condensing
Mechanical Durability 1,000,000 cycles
Dielectric Strength >2kVAC 1min
Power Consumption ≤2W
Mounting 35mm DIN rail
Weight 130g
Dimensions (H*W*D) 79*23*79mm
Certification CE

Wiring Diagram:

DC voltage monitor relay wiring diagram

Dimension: (Unit: mm)

DC voltage monitor relay dimension
Tips: Why you Need DC Voltage Monitoring Relay From ATO Manufacturer?

  1. High precision. Voltage monitoring relay adopts powerful microprocessor chip, traditional technology adopts AC sampling technology, voltage measurement accuracy is ±1%, new technology adopts true RMS measurement technology, measurement is more accurate, error is less than 1%, and it can Displays the phase voltage values of the three-phase power supply respectively, which is equivalent to the function of three voltmeters.
  2. Wide power supply voltage. Voltage monitoring relay can be applied to phase voltage 150~300V (line voltage 250~500V), which greatly reduces the specifications of the phase sequence protector, which is convenient for users to choose, and can reduce a lot of spare parts funds.
  3. Independent normally open and normally closed output. The voltage monitoring relay adopts high-power double-group contact relays, which can independently control equipment of different voltage levels and are more widely used.
  4. Intuitive display. The special wide temperature and high clear LCD display is adopted, which can display the phase voltage of three-phase power supply under normal operation, and directly display the cause of fault when the fault occurs, and can also display which phase fault and the voltage value when the fault occurs.
  5. Fault record. Voltage monitoring relay adopts non-volatile storage technology. When overvoltage, undervoltage, phase loss, unbalance, and phase sequence faults occur, faults are recorded. Even if the product is completely powered off, it can also memorize fault information, which is convenient for fault inquiry.
  6. Installation method. The base of the Voltage monitoring relay adopts the guide rail type and has two M4 screw holes. It can be installed on the HT35 guide rail or fixed with M4 screws. The two installation methods are more flexible and convenient.
  7. Humanized voltage unbalance protection. An optimized mathematical model is established inside the Voltage monitoring relay, which can automatically adjust the action time according to the three-phase voltage unbalance, without user settings.

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