mep 804a not working.

[Guyfang]

When I switched it from 50 hertz to 60 it continued to run but pegged the meter past 62. once I cut the generator off and tried to restart it with the switch set on 60 hertz, the over voltage light came on and the gen set cut off as soon as I let off of the start switch.

Did you move the S12, Freq switch back and forth while running the set?
The S12 tells the A1, AC volt regulator what Frequency it is supposed to produce. One of the functions of the A1 is Over volt shut off of the set. The A1 may have become "confused". After you turned the set off again, and is shut down when you released the S1, I assume you had beforehand reset the A2, Fault Indicator? If you do not reset it every time a fault light comes on, it will continue to shut the set down. Try this. Place the S1 in the run position. Reset the A2. Then start the set normally. When it reaches the proper AC voltage, CONTINUE to hold S1 up. Flip the S7, Battle short switch up. Let S1 go. What idiot light comes on?

 

[Guyfang]

Does the governor on the back of the injector pump look like its been molester, I mean, worked on by a 52d? can you adjust the hz down before it safety's out?

I don't think that's the problem. It ran fine before, according to the OP.

 

[Dewie38]

Check the resistor on the back of S12.

 

[Guyfang]

Good call Dewie. That is but one thing that needs to be checked.

Below is an answer to our question from someone who knows more about this then I do.He does gen set repairs for a living. I had to edit it a bit.
Gen sets usually run the best if they run as designed. Changing things in the middle of operations seems to make them burp.

WOW! K5 Kicks in when you play with the S12 while running, on a 15KW. That magnetic field in the main gen is doing back flips. What a surprise, K5 trips that’s all? After doing that you might need a new K5, A5, R16 and once in a while a new Voltage sensing Transformer and I’ll bet the regulator was having lots of fun. The LMU was having kittens also. Does he see black goo running out of those black boxes yet?
He does realize what was going on there. All the regulating components have to deal with a sudden frequency change of the engine and has to try to keep up the voltage at the set point. The A5 is being told to drop 300 RPM in an instant, and the engine and components are having lots of fun. I think lots of folks have done this. Then they call us. You might get away with it once. Then you call us. This is why the “how it operates” says to do all that BEFORE you start the thing.
If that fault persists keeping things from running so well, remove and tape wire 203A at the K5 and tape it. The fault panel, that of course was reset before you started all this, won’t see that the K5 is bad. Best to check out the output as the gen comes up though. That marathon main gen is not all that swift.
Now tell him to pull the K5 when you get down time and drill the rivets out and prepare to fix what is busted inside.