Overvoltage Protection Modules

Because of how and where they are used, surge protection products must be versatile to ensure safe and error--free protection. WAGO's overvoltage protection products ensure reliable protection of electrical equipment and electronic systems against the effects of high voltages.

Product overview

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Ground Fault Detection

Increasing Availability via Improved and Preventive Maintenance

According to the IEC 60204-1 standard, measures must be taken to reduce the probability of malfunctions due to insulation faults/ground faults in a control circuit. A common option is connecting 0 V to the ground potential in the control circuit, in combination with an upstream fuse. With the new ground resistance signaling module (789-665), WAGO offers the possibility of detecting not only the grounding of the 0V potential, but also the full and automatic undershooting of a non-adjustable, unbalanced insulation resistance between +24 V or 0 V of the supply voltage and ground. An integrated potential-free contact can be used to signal the Iso OK status to a controller, for example, a PLC. Additionally, on-module LEDs clearly indicate the insulation fault to the operator. Compared to mechanical ground conductor disconnect terminal blocks, maintenance is considerably simplified. Early detection of imminent ground faults enables improved preventive maintenance, ensuring increased system uptime.

The module can be used in single-phase grounded and ungrounded control circuits, but it does not meet the requirements for insulation monitoring devices according to IEC 61557-8. A slide switch allows the user to select the grounded/ungrounded control circuit operating mode. With the new ground resistance signaling module, it is possible to upgrade from the former manual testing of a ground fault to a permanent test of the insulation resistance.

Your Benefits:

  • Automated insulation resistance measurement
  • Early detection of potential ground faults
  • Insulation fault indication via LEDs and potential-free contact

Our Overvoltage Protection and Specialty Electronic Products

Protection Devices

With overvoltage protection, electrical equipment and systems can be reliably proteced against high voltage thus ensuring system availability.


  • Protection of the system against overvoltage by using the overvoltage protection modules
  • Space saving thanks to the narrow design
  • Cost savings by preventing downtime
  • High operational safety and system availability by avoiding equipment errors due to over voltage

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