Tuning a Generator?

[Diggin It]

I can't tune a piano, nor can tuna fish and don't even ask me to carry a tune, but can I tune a generator?

I have an ETQ (Eastern Tools) 8250. Off brand that used to be OK, but they shut down all operations. It starts and runs fine, but the output power is dirty. My various UPSs and battery backups puke on it, all sorts of buzzing and bleeping from them. I'm not sure if the voltage is varying or the cycles, but they don't like it at all. I found it was easier to buy a smaller HF 2K inverter to power those.

Thing is, the big one runs motors like the fridge and A/C just fine, and if I have a heavier load on it (like a radiant heater), the UPSs don't act up.

Somebody suggested the brushes on the genset mike be worn or out of tolerance, but I have no idea where they even are or if they require disassembly deeper than I'm comfortable with. While I have basic tools and meters, I don't have anything capable of measuring that kind of output to any fine degree.

And, I don't know of any shops nearby that might even want to try it.

 

[orezok]

If there are any lakes near you, that generator would make a great anchor

 

[LouNY]

On the small portables most of them are quite similar,
attached is a video on changing the brushes.
How to Change your Generator's Carbon Brushes - YouTube

 

[Roadworthy]

It sounds to me like it doesn't regulate into a light or zero load. If it was a brush problem my expectation would be inadequate current output - an inability to keep up with the load. If it works when loaded to about fifty percent capacity I don't believe you have a problem. It should be run for awhile every month or two just so it gets some "exercise".

 

[SPYDERLK]

Dirty is usually rather high in frequency. Id try 3 capacitors: L1-L2, L1-N, L2-N at the gen output to siphon off the high freq. I think Surplus Center has some fairly low value 440VAC caps at good price.

 

[Diggin It]

^^ Only way I can check quickly is to plug a Kill-A-Watt into one of the outlets and check the input frequency.

 

[SPYDERLK]

"Dirty" is usually rather high in frequency. Id try 3 capacitors: L1-L2, L1-N, L2-N at the gen output to siphon off the high freq. I think Surplus Center has some fairly low value 440VAC caps at good price.

^^ Only way I can check quickly is to plug a Kill-A-Watt into one of the outlets and check the input frequency.

The "dirty" is actually a HF superimposed on the major sine wave that is dependent on RPM. On an oscilloscope you see the sine wave as fuzzy - not a clean line. The HF may not be sine at all, but a myriad on fast occurring spikes riding the 60HZ. The spikes dont amount to much energy but can confuse or wreak havoc on electronics that does not have built in filtering. A capacitor will essentially short out the spikes.

I dont think your Kill A Watt would respond to the high freqs - youd just get the major wave reading.

 

[RNeumann]

Without knowing output voltage (hopefully the meter you have) and frequency/hrz (Kill-a-watt ot other meter) you are taking shots in the dark.

I’d be worried about the frig etc.....those compressors “run fine” till they don’t.

 

[Diggin It]

I've had the Kill-A-Watt on it before and the voltage is fine, relatively stable too, 120-123 or so as I recall, but I'd have to check again to be sure.

 

[jayincmh]

You also need to check the output Hz. Sounds like the HZ (which can be connected to RPM on a generator) is off...and when its under load it corrects itself. I had that issue on a DAC generator.

 

[Diggin It]

Quick test run with Kill-A-Watt connected.

No load, 121.3 V with little variation. Frequency about 63Hz with slight variation to about 63.5 or so. Energize a 1500 radiant heater, you hear a slight change in engine tone and the frequency drops to around 61 Hz. De-energize the heater and the previous numbers come back. Heater has two switches to select lo or high. With only one switch on, the frequency is in between, around 62Hz.

I have no idea how to adjust that or if it's even possible. Or if it would matter.

 

[SPYDERLK]

That means its running a little fast at low load. Not enough to be trouble. It probably settles to 60HZ at about mid capacity and a little lower at full load. Not bad.