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Warren&Renee · 08-02-2008, 05:36 PM

Greetings,
Recently I was checking the voltage and frequency settings on my 1999 Generac Series Q-55G and discovered that the frequency is running about 128 Hz. The unloaded voltage is running about 126V. I don't have a way of determining the engine RPM but it appears to be running in a normal range. Does anyone have any thoughts on why the frequency might be running so high? Any input would be greatly appreciated.
Thanks,
Warren

Warren&Renee · 08-02-2008, 05:36 PM

Greetings,
Recently I was checking the voltage and frequency settings on my 1999 Generac Series Q-55G and discovered that the frequency is running about 128 Hz. The unloaded voltage is running about 126V. I don't have a way of determining the engine RPM but it appears to be running in a normal range. Does anyone have any thoughts on why the frequency might be running so high? Any input would be greatly appreciated.
Thanks,
Warren

SCVJeff · 08-02-2008, 07:57 PM

Are you sure you're not reading the 2nd harmonic of 60Hz, and it's not really 64Hz unloaded? That being the case, 64Hz isn't unreasonable (unloaded). If not, you have issues, but I seriously doubt it's running 3600RPM without noticing..

J Walker · 08-03-2008, 05:20 AM

Most assuredly you are reading the second harmonic of nominal 60 Hz or you are getting a factor of 2 in your reading. If your frequency was truly doubled you would have problems all over your rig. Doubling the frequency would double the voltage out of all transformer or inductive loads. It would be a major catastrophe.

Warren&Renee · 08-03-2008, 01:18 PM

Thanks for your input Jeff & Jim. I thought it might be a harmonic but wasn't sure. I went ahead and checked the frequency under a small load and it was 64 Hz. As soon as I remove the load it goes back to 128 Hz. Any thoughts why I would read a harmonic instead of the primary frequency when the unit is unloaded? Is this normal? The instructions for setting the frequency & voltage require a no load condition for the initial reads and adjustments. Nothing is mentioned about a reading a harmonic.
FYI: I recently purchased this coach and have been dealing with several electrical problems. It appears that there might have been a surge or spike on the electrical system because the microwave, the primary TV and the VCR are inoperative. The microwave had a cracked varistor and a smoked transformer & relay on the "Smartboard". The TV doesn't appear to have any obvious problems but it's out for the count. The VCR had a blown fuse.
I would think that a surge/spike that the electrical system might have experienced was from an external source. But, with the generator acting strangely I'm uncertain.
Thanks again for you assistance.
Warren

SCVJeff · 08-03-2008, 06:10 PM

It's hard to say why you are getting an unloaded reading like that. I've never heard of this before, but if I were to venture a guess I would say that you're being fooled by essentially an un-terminated "load", and if you fiddle with RF, all kinds of crazy things can happen with un-terminated transmitters (or generators in this case).

Fire up the A/C and run your checks and adjustments with that load on it and you should be fine.

Jeff
PS- I see we're neighbors...

Warren&Renee · 08-05-2008, 06:48 PM

Thanks for the input Jeff. I spoke with a Generac Technician today and he pretty much confirmed what you are saying. He seems to think it might have something to do with the meter I am using though. He says it has to be a harmonic I am reading and not to worry.
This issue has got me thinking about power quality and how to monitor & avoid harmful conditions. After a little research on the subject I discovered an Electrical Management System that appears to be just what the doctor ordered. The device's model number is EMS-HW50C and it's made by Progressive Industries. It connects to the AC system and monitors & protects against high/low voltage conditions, reverse polarity, open neutral, open ground, surge protection and AC frequency protection. I plan on ordering it tomorrow.
Thanks again neighbor,
Warren

SCVJeff · 08-05-2008, 08:20 PM

If you really get in a pickle let me know. I have a simple box with a AC voltmeter and freq meter with a plug on the end built specifically to tune up non-inverter generators. The meter can't be fooled since it's only looking at +-5Hz or so.. Plug it in, bring it to the generator and tweak.

Route 66 · 08-06-2008, 03:05 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">After a little research on the subject I discovered an Electrical Management System that appears to be just what the doctor ordered. The device's model number is EMS-HW50C </div></BLOCKQUOTE>

I and many others use that unit for protection and to keep an eye on the power.