Early ground fault detection

By OEM Update Editorial April 4, 2022 12:01 pm IST

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 signalling module, WAGO offers the possibility of detecting not only the 0 V grounding, 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. Additionally, on-module LEDs clearly indicate the insulation fault to the operator.

Compared to mechanical ground conductor disconnect terminal blocks, maintenance is considerably simplified. With this new module, a permanent insulation resistance test can now be performed every three months instead of the standard manual ground fault test. Early detection of imminent ground faults enables improved preventive maintenance, ensuring increased system uptime. A slide switch allows the user to select the grounded/ ungrounded control circuit operating mode. However, the module does not meet the requirements for insulation monitoring devices according to IEC 61557-8.

Why does the standard require taking measures against ground faults? 

Ground faults in control circuits can cause the problems such as: Unintentionally starting dangerous movements or preventing the emergency shutdown of machinery (safety risk) as well as Distortion of analog signals (no correct process flow)

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Preventive maintenance, in the form of early detection, allows for maximum repair time that avoids immediate plant shutdown (loss of production).

Advantages of the ground resistance signalling module over mechanical ground conductor disconnect terminal block- 

• Replacement of the manual test for incipient ground faults 
• Reduction of the inspection interval from approx.3 months to 10 seconds 
• Potential-free contact allows immediate signalling to a PLC.

Visit https://bit.ly/3sP2ar4 for more information or send us an email at marketing.india@wago.com