Generator Over Voltage – What Possible Cause?

Generator over voltage can occur randomly, especially when supporting machinery.

Carefully check the following to isolate the possible root causes:

  • Are setpoints too restrictive after full load rejection?

    Firstly, check the loads that the generator is supporting are not imbalanced .
    Secondly, ensure all loads are balanced across the 3 phases.
    Check the load dropping onto the generators is not cutting IN and OUT too quickly.
    If the load is intermittent it could be too quick for the generator to support the load.
    The voltage parameters may need adjustment.
    All off the above can cause generator over voltagegenerator over voltage checks

  • AVR failure

    Ensure the AVR is fully functional as this can cause generator over voltage issues.
    As the AVR controls voltage, this is often the reason for voltage issues.
    Of course, this requires a generator engineer with a laptop to plug into the system.
    Call your dealer to arrange this AVR functionally test.
    Replace the AVR if necessary.
    AVR failure does happen.

  • Lightning strikes on power lines?Grid power lightning strikes will effect your generator operation.
    Importantly, check that your site has not been affected by lightning strikes in the past 24 hours.
    Also ensure that the generator has a good earth connection.
    Earth connections can work lose over time, due to rust or vibration.
    Generator engineers can check this next time there is a maintenance visit.
  • Clear the alarm on your control panel.

Then, restart the generator to check if the fault reappears.
Should the generator over voltage keep occurring, then carry the above checks once more.
Thereafter, contact your local generator dealership to carry out a full investigation.

The above tests should highlight the cause and therefore the solution to the problem. However, be sure to contact your local dealer if the generator over-voltage issue remains.

Also read the following helpful advice on Power Continuity Knowledge Resource

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