Generac and frequency control

Nate · 2007-08-01T12:52:56+00:00

There are a few other posts about this but I'm going to chime inalso.We just installed a Generac 16KW generator at our office to supply ourserver room, network backbone, phone system, and supporting airconditioning. First test after installation showed that every APC UPSwould NOT accept the power from the generator... this is pretty muchall of the gear that we are trying to protect. Frequency checks onthe generator indicate that it's low... around 57 to 58 Hz (no meansto adjust it). Called Generac and was told this is a known issue andthat this generator won't maintain 60 Hz until it's loaded to theupper end of it's capacity (we're currently running about 55% load).I'm pretty surprised that Generac is selling a product like this andapparently it's only an issue in their V-twin engine models. I'veworked in the electrical generation/distribution field and I've neverheard of anything like this before. Even my cheap house and campergenerators maintain frequency throughout their load range.One additional note on the UPS units. We noticed that the Tripp Litesdo accept the power because their frequency tolerance is twice that ofthe APC line. Also, the larger rack mount APCs do have a sensitivityadjustment which, when adjusted fully, will accept the low freqpower. End result is that we're looking at replacing all our smallerUPS units or working in additional load to the generator.

Aug 01, 2007 21 Replies

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Neon John 18 years ago

Keep reading in the section about load testing.

John

-- John De Armond See my website for my current email address

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Pete C. 18 years ago

The inverter type generators are a great innovation. Now if they'll just put a small Li-Po or similar battery pack in there to help further cover sudden loads while the engine gets up to speed.

Pete C.

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