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Generator cutting off power

My coach has a Powertech. The voltage regulator went bad and was replaced 3-4 months ago.
When I run all 4 roof AC after about an hour it will cut off power. The engine keeps running. It will continue to cycle power on/off every 3-4 minutes. If I cut it back to 3 roof AC it will run and produce power no problem.
Any idea where to start?

Do you know what the model number of the regulator is?  Voltage regulators started using a volts per hertz roll off feature some 25 years ago.  I know this sounds confusing but it is really simple.  As the engine speed decreases, the regulator’s output is reduced to the exciter which results in a reduced output voltage.  Depending on the regulator model, it can be fixed or adjustable.

At a first guess, it sounds as if the load on the engine is slowing it down and the voltage is dropping too low.  The kubota engine’s governor operates on a droop governing principle whereby the engine looses speed from a fixed position as load is applied.  Most all sets are configured this way.  There are some later models with isochronous governing (steady state speed regardless of load).  The droop is usually 3 to 5% but as the engine ages this can open up to much larger percentages.  What this means is, your engine’s speed may be low enough to trigger a fixed roll off setting in the regulator.  

Did the speed get checked when replacing the regulator, if v/hz is adjustable, did it get set to match the engine speed?

This is my best guess with the limited amount of information provided.

Gordon Jones

On my service ticket it says 63-4 AVC, 06REG634AVC
It’s on a 2005 coach. It said they set the dials to the same and installed new one.

Do you have any way to read the frequency when it is running with 3 AC’s online?

Gordon Jones

That is a PEARL from someone who knows what is what!

Now that it is said, it makes perfect sense. If you don’t have a clamp on meter that will read current and frequency, you should.

Easy peasy way to see if the genset is bogging down.

Richard and Rhonda Entrekin
99 Newell, 512
Subaru Outback Toad
Inverness, FL (when we're home Cool )

I do have a meter I can clamp on and check that.
My coach had the transfer switch replaced and hasn’t had the silverleaf updated (so I was told) so I can’t see what power is being drawn that way at all.

My power tech will do the same. The airs will be running fine, then off for a few seconds, then back on. I have not replaced the voltage regulator, yet.

Ernie Ekberg
Prevost Liberty-sold
Ernie Ekbergs Flooring on Facebook
[email protected]

To follow up with what the issue was, at some point one of the AC had been switched to the wrong leg of the generator and causing it to pull too much power.

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