Generator AVR – What is the AVR?

The Generator AVR is a small electronic device that sits on the alternator monitoring the power output. You may never even notice it. This small electronic device automatically maintains the generator electrical output terminal voltage within pre-set manufacturers parameters.

The Automatic Voltage Regulator (AVR) is usually fitted on all modern diesel generators to maintain constant voltages. It’s like type of power conditioning, ensuring that the generator power to the site equipment load remains constant. Without a functioning AVR the generator output could vary widely, causing disruption to the site. The AVR smooth’s out the constant power output of the generator.

How do I know that my AVR is working?

If your generator is working fine- No AVR problem
Never look for an issue when there are no issues.

How would I know if there is NO AVR Fitted?

All modern diesel generators have an AVR fitted as standard

How would I know if the AVR has failed?

Generator hunting and surging randomly or erratically. This can occur when the generator is under load, whereas before the generator was running perfectly normally then suddenly your generator struggles.

You’ll first become aware of this, because you’ll hear the engine struggling or hunting randomly.

Check the control panel for frequency fluctuations.
You may find that on the control panel you can see the frequency drop and rise erratically whilst you’re watching.

Watch the video for an example how a failed AVR affects the generator output.

Contact your generator supplier who can send out an engineer with a laptop to log into your control panel. Once inside the software, he can determine whether this is the AVR fault or not, fuel issue or it’s your site load is the issue. Should an AVR require replacement then do so immediately.

Whatever you do NOT operate the generator if the AVR has failed.

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