Generator breaker keeps shutting off immediately

[SHRED]

1995 Lazy Daze.
Onan generator.
Progressive Dynamics PD4645 converter.

There is no power reaching the motorhome from the generator.

I tested the leads to the breaker. One read about 170VAC with generator running. I shut the generator off and tested the other lead and it tested .266 kilohms so I don't think there is a short but I'm not very electrically literate.

I replaced the switch. That didn't fix.

AC voltage works fine when I plug into shore power.

I'm wondering what next to check.
Thanks.

[MEXICOWANDERER]

Not definitive. Use 12 volts. A battery, a 0 ohm resistance will induce a substantial spark. No substantial spark no short. Use positive on the slip ring furthest outboard. This induces inherent magnetism.

Opens are common direct shorts are rare. Check 20 M resistance slip ring to generator chassis.

[dougrainer]

SHRED wrote:
Update:

Replaced brushes and springs.
Shined the rings.
That brought my stationary ohm reading into tolerance on the 9/10 pins at 25 ohms.

Problem is during spinning the ohms flucuate from 0.00 to OL at those same pins.
I think I have a short in the rotor.

Hope not, expensive fix. You CAN buy a re-wound Onan Armature for a lot less than new. Doug

[SHRED]

Update:

Replaced brushes and springs.
Shined the rings.
That brought my stationary ohm reading into tolerance on the 9/10 pins at 25 ohms.

Problem is during spinning the ohms flucuate from 0.00 to OL at those same pins.
I think I have a short in the rotor.

[SHRED]

UPDATE

I followed this video for testing.

MEASURING YOUR GENERATOR WINDINGS

I then called Flight Systems with the results.
They are so helpful.

Pins 9 and 10 test was not good.
I've got new brushes and springs coming plus I need to shine up the rings.

Chances are my regulator is damaged they said by the fluctuations from the brushes not making good contact.

That video is very helpful.

[SHRED]

Good news I think.
I unhooked the ATS and the generator breaker stayed on.

My next question is...If the generator output is indeed 170VAC as it tests, could that voltage harm the ATS?

The running RPM of the generator does not appear to run any higher than normal.

[SHRED]

Good news I think.
I unhooked the ATS and the generator breaker stayed on.

My next question is...If the generator output is indeed 170VAC as it tests, could that voltage harm the ATS?

The running RPM of the generator does not appear to run any higher than normal.

[Gjac]

Does your genset seem like it is running at a higher rpm than normal? You can buy cheap HZ meter plug it into your 120 v socket and adjust the speed to read the correct HZ at the proper rpm.

[Bobbo]

Since it is an ONAN, check CUMMINS/ONAN's website for certified service centers in your area.

[YC_1]

SHRED wrote:
Would a bad Automatic Transfer Switch cause the genset breaker to trip off?

Yes, and you could lift the wires off it for a test but as mentioned, that voltage is far too high. You could have two problems.

The high voltage could have toasted something that has now become a short or at least enough of a load/short that it trips the breaker.

I would assume you have checked the voltage on other things with your meter such as the shoreline outlet. Just to assure your meter is working correctly.

If shoreline power is working fine and nothing is NOT working inside, that is the microwave and any other electrical devices are working then the short would seem to be from the transfer panel towards the generator.

There could be a partially melted wire touching the frame of the rv that has just a few strands touching.

Lifting the wires off the transfer switch that come from the generator should check that. If the thing still trips, pull the wire off the generator breaker and put your meter into the Ohm position or continuity test and check the wires that are now disconnected from both ends.

[dougrainer]

SHRED wrote:
Would a bad Automatic Transfer Switch cause the genset breaker to trip off?

Yes, Shorted contac points or BURNT Transfer relay/wires at the Transfer box. BUT, THERE SHOULD NOT BE 170 VOLTS, PERIOD! THIS is what you need to look at. Doug

[SHRED]

Would a bad Automatic Transfer Switch cause the genset breaker to trip off?

[time2roll]

SHRED wrote:

time2roll wrote:
170v sounds like a regulator issue or an open neutral. Best to have a pro look at this issue.

I'm in Encinitas, CA (San Diego County).
Do you know of any good shops in my area?

I don't.

My best shot would be to call someone 5 star rated on YELP.

https://www.yelp.com/search?find_desc=onan%20rv%20repair&find_loc=Encinitas%2C%20CA%2092024

Hopefully someone will soon post a good shop in your area.

[ndrorder]

170VAC is too high. Disconnect the output wires from the generator breaker to get a good measurement of the voltage between the common and neutral connections at the breaker while the generator is running. If this is more than 132 VAC, generator issues need to be resolved before continuing.

The next step is to isolate the wire past the generator. So with the generator off, leave the output wires from the breaker disconnected and disconnect the generator input wires at the automatic transfer switch (ATS), or unplug the shore power from the generator receptacle. Now measure resistance between the common and neutral wires and common and ground wires. If anything other than an open circuit is measured, there is a short in the wire between the generator and ATS or receptacle that needs to be corrected. Best guess is, because of age, there is a generator receptacle and something inside that box has giggled loose and is shorting.

[SHRED]

KMLsquared wrote:
While I agree 170VAC is too high, I don't see why that would be tripping a over current device like a breaker. If all down stream loads are off and its tripping there must be a short between that generator breaker and the main breaker of the 120VAC distribution panel. Start tracing wires and opening junction boxes.

Odd the 170V as that is the peak voltage of 120VAC. Is your meter a good one or a cheap harbor freight one?

This is my meter.
It's been very accurate for other applications.

METER