Generator Hunting and Surging

Generator is hunting and surging erratically.

What are the signs your generator is hunting and surging? Listen for the engine struggling or hunting randomly.

If you can hear this, check the frequency on the control panel. You may see it rise and fall erratically whilst you’re watching.

Here is what a Generator start up should sound like:

Usual causes of generator hunting and surging – solutions

Fuel blockage or restriction: Firstly, check filters and fuel quality.

Fuel pump – intermittent fault: Check for leaks or lack of fuel. Generator oil checks hunting and surging

Machinery has suddenly started up and caused a wild spike load. This is beyond the range of your generator and it is struggling to cope.

Motor drives downstream are going ON & OFF erratically. Moreover, this is causing generator overload.

Unbalanced generator load that keeps increasing and decreasing.

Old motor drives without electronic governors starting up. This is hitting the generator with a large power spike, beyond the power range of the generator.

Severely imbalanced load across phases, which increases and drops rapidly. E.g. Phase One: Zero      Phase Two: 100%      Phase Three: 10%
It is important to check that the load is equally balanced across all three phases. Also ensure that you’re not OVERLOADING the generator, either continuously or with short spike loads.

NO functioning AVR on the generator – Basic alternator/governor.
Arrange for the installation of a new AVR. Contact your generator installer for assistance with this.

AVR failure or intermittent AVR failure.
The AVR (Automatic Voltage Regulator) is a small device that sits on the alternator, monitoring the power output. You may never even notice it.
The AVR is there to maintain constant voltage and power line conditioning to the equipment load. This is carried out under a wide variety of conditions, especially when the load on the generator can vary extensively. The AVR smooths out the constant power output of the generator.

Contact your generator supplier, who can send out an engineer with a laptop to log into your control panel. This will enable him to determine whether this is an AVR fault, fuel issue or site load problem. Whatever you do, DO NOT operate the generator whilst it is struggling.

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