ONAN Generator Output

[john massey]

I have a 1977 Royale and we are finally back at home after being out
for about three months. I was checking out my batteries and decided that
while the weather was nice I'd run the generator for an hour which I do each
month. I rarely use it since generally have shore power.
While it was running I decided to check its output with my digital
voltmeter and got a disturbing reading. With a 1500 watt load it was putting
out 145 V ac, removing the load, it went to 155 V ac. Checked the meter
against the shore power and it read 115V ac. What gives?
During the past months I've used the generator several times to power
the TV and electric heater with no problem.
I've got the GMC in August and one of the things I do not have is an
Onan owners manual.

John Massey

 

[9675.0203]

John,
Per the Onan manual, "Engine speed determines the output voltage and
frequency of the generator"

This is a function of the 'governor'. Again per the manual, the maximum
no-load voltage should be 126 volts, the minimum full-load voltage
should be 110 volts. Maximum no-load speed should be 1890 rpm, 63 hertz;
minimum full-load speed should be 1770 rpm, 59 hertz.

High voltage output means high frequency also. On prolonged useage, this
could damgage the appliances connected to it.

Does your gen motor surge or 'hunt'? This can be caused by any of the
folowing: carburator adjusment, fuel filter, fuel pump, valve or valve
seal leakage, or the throtle and governor adjustment/condition.

Hope this helps,

HR in Indy
9675.0203

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>
> While it was running I decided to check its output with my digital
> voltmeter and got a disturbing reading. With a 1500 watt load it was putting
> out 145 V ac, removing the load, it went to 155 V ac. Checked the meter
> against the shore power and it read 115V ac. What gives?
> During the past months I've used the generator several times to power
> the TV and electric heater with no problem.
> John Massey