The uneven speed of diesel generator set is mostly caused by the abnormal resistance of the parts of the injection pump and governor and the slow response of the governor. Generally, there are two kinds of performance. One is a large swing, the voice is clearly identifiable, commonly known as gasp or tour car. The other is that the speed fluctuates in a small range, the sound is not easy to appear at low speed, which will lead to the diesel engine flameout. The following are eight reason for the uneven speed of diesel generator sets.
SOURCE: Generac Guardian 15kW Generator
That sounds just about right, if the relay contacts get welded together it sometimes takes out the driver on the printed circuit board. As you found out, 12vdc from 23 to 194 makes the transfer switch move to the Generator position, relay not energized makes the ATS move to the Normal position.
You can make a nice test function by installing a 10 amp contact switch in series with either the N1 or N2 terminals. When the switch is open the generator thinks the Normal power has failed.
Regards,
Carl
SOURCE: 10kw Generac shut down overspeed
Make sure that the throttle linkage is all there and not damaged/misadjusted, then get a manometer and check your inlet gas pressure. Gas pressure should be 8 inches of water column and stay there running or not.
Carl
SOURCE: Attempted to start Generac Guardian 15 kw air
I work on these every day. Its either gonna be the rotor or stater, the voltage regulator, but most likely its a bad stepper motor which is the throttle motor, or control board. Thats all that could be causing that so its one of those. If its the rotor or stater thats bad it causes the generator to RPM up because it thinks its not producing enough power due to that. I had the same problem with the same one we just fixed and it was the slip rings on the end of the rotor so bad rotor.
SOURCE: Generator Transfer Problem
There isn't much you can do with servicing the generator set or transfer switch unless you've got lots of experience in diagnoising semi-conductors and electronic components.
Depending on the age of the system, it would be benificial to have a qualified service tech take a look at it.
As an electrician, I've installed several back up generator sets in homes for customers and have had a few of these automatic transfer switches with intermittent operation issues. Sometimes it's the switch and other times it's the Generator that is causing the problems.
Hope this helps, and best regards!
SOURCE: Generac 43903 standby Generator overspeed indicator on starting
I have a generator that did the same thing. It would start and then stop within a few seconds. The more expensive generators have an oil level safety switch to prevent the engine from burning up. There is usually a wire connecting to the switch on the outside of the engine near the oil fill hole. Remove this wire and try to start the generator. If it runs without a problem then it is the switch. You need to remove the switch and take it apart carefully and clean it. There is a small float inside the assembly. When the oil runs low the float allows the switch to short to ground which kills the spark to the spark plug. Hope that helps.
Bob Janelli
I’m happy to help further over the phone at https://www.6ya.com/expert/bob_62dfa2f81bb55288
Testimonial: "This is good information in the event that the low oil switch is part of the problem."
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