Frequency Variation MEP-803A

When I startup my MEP-803A with no load and apply different loads, it's impossible to keep it at 60HZ without making manual adjustments.

Is that how it is supposed to work? Is there a maximum variation from 60HZ I should be looking for?

I'm not exactly sure yet where to leave it. I know what the always on load will be but that's pretty low - maybe 1000W. I know what the load will be with the AC running or maybe the water heater. Not sure which amount of load should be tuned for exactly 60HZ.

I set mine to about 61.5hz with no load. Fully loaded that gives me just about 60hz.

DieselAddict said:

I set mine to about 61.5hz with no load. Fully loaded that gives me just about 60hz.

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Thanks. I'll try a few different external meters and see if I can get it that close.

Usually you will get 1-3 drops in hertz. If it drops more, then you need to adjust the governor.

Review page 4-15 in TM-9-6115-642-24 for Frequency Droop Adjustment. It will refer you to the performance characteristics on page 1-7.
Here is a print screen for the frequency characteristics.


I tried adjusting mine and couldn't get better than 3% from no load to loaded at 50 amps. I set mine to 62.5 unloaded with a digital meter. There was no change in mine after a couple of turns on the governor screw so I decided to live with it. According to the chart the adjustment range would be 58.2 to 61.8 hz.

Are you basing this solely on what the panel gauge is telling you?

Light in the Dark said:

Are you basing this solely on what the panel gauge is telling you?

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. No, the gauge seems to be off/broken. It's off by at least 1 HZ. I was using a Kill-a-Watt device to get readings. I didn't realize I might want to get a permanent frequency/voltage meter now that I see how inexpensive they are.

I also need to adjust my voltage. At first I was set to 111V per leg. My utility power is 123V per leg. While I was out there, I forgot what I was shooting for specifically.

Bob, one hertz isn't even a measurement. If you are worried about one hertz, go buy a nuke plant. I don't care what you have in the house, nothing will squeal over a one hertz difference. Your house power will fluctuate more then that. Don't go overboard. There are too many other things to worry about.

The dial is off by 1Hz but that wasn't my problem. My concern is a larger change from idle to full load. I recall it was 3 Hz.

As others have said, you will find to set hertz higher (61.5 is a real good starting point) and give 'her ****, and adjust the hertz once your load has been determined. It should hum there pretty well (even considering tolerance range) for as long as you have fuel.

And yes, most modern power supplies built into products are autoswitchable units (meaning they are universal voltage input, 50/60hz)... so they are gonna run no matter what your MEP throws down the pipe. I routinely see grid power dip to mid 50s for short durations all the time (see it on our large server UPS when I am at work).