Is it the Voltage regulator?

[Jens]

Hi,

I have a Craftsman (Generac) 6300 Watt AC Generator, model #580.326300.

Until the other day it had been vworking fine. Then suddenly after starting it up the out put was only 6V in the 120V plug.

I started to take the generator apart to get some measurements. The voltage to excite the Field was only 0.2V, so I grabbed an old battery I had lying around (output 9V) and connected it to the Field. Voila, now the output was up around 70 Volt. But it went back down to 6V as soon as I disconnected the battery.

With my (very) limited knowledge of generators of this type. I would say it is the Voltage Regulator board that is dead.

Any Ideas, toughts, other tests I can try ?

Regards,

Jens

[drdongle]

Sounds like a problem with the field control and voltage sensing ckt.

[Nando]

Jens:

It seems that the AVR is not receiving voltage feedback for proper operation and voltage control.

Is the AVR encased in plastic ( epoxy) or is it repairable ?.

I am not familiar with that generator so I can not give you good advice.

Nando

[Jens]

The AVR is encased in epoxy, not much hope for a repair. However there is a small screw/potentiometer I don't know what it does. But I was hoping that there was something else that might be the cause.

The AVR energises both the rotor and the stator both meassured about 0.2V. I completely forgot about about the feedback wire.

I'll try to get a reading on the feedback when jolting the rotor and try to get a reading on the feedback wire.

With a dead AVR, the power generated is due to residual magnetism, right?

Jens

[Nando]

Jens:

Yes the feed back wire loss will limit the voltage build up just enough to start producing voltage, so check the feedback wire that is the voltage that is used to produce the forward rotor field energy for the generator to produce full voltage.

I have the impression that the AVR is OK, since you put a battery that increased the voltage to 70 volts, try a higher voltage but do not load the generator to avoid demanding excessive current from the added voltage source, most of them use around 60 volts to produce peak voltage but with up to some extra amps of feed back (or supplied voltage).

Good luck

Nando

[Jens]

I did some more measurements.

The feedback is ok.

The exciter for the stator is seems to be working fine. The current flows through up to 120V AC the it drops suddenly.

But the Rotor exciter stays at 0.2V DC no matter what.

Jens