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Standby generator trip on overspeed
We have an standby generator installed. It starts and run but after about 30 minutes it stops running.

We have an standby generator installed. It starts and run but after about 30 minutes it stops running. It trips on overspeed. That happens on several occacion. Does some-one know about the possible problem?

Not enough details.
What is the generator type?
What control system?
Is the generator tripping on mechanical overspeed or electronic overspeed?
If electronic, what brand and type is the electronic overspeed relay?

it's looking like the air filter is not ok, check it.

also check the RPM metter to see if it is giving a real revolution per minute.

What's the color of the smoke of the generator??

if it is white check the fuel filters.

if it is black turn it on without the air filter to see how long it last on.

By Bob Peterson on 30 March, 2004 - 5:12 pm

Is it actually overspeeding? or is the trip circuit malfunctioning?

If it really is overspeeding than your regulator is probably not functioning properly. Or you could have an issue with the load varrying too fast.

Not really enough info to give you much help.

By daniel hohm on 4 April, 2004 - 11:14 am

I am an engineer that designs engine control systems for generators, so this is right up my alley. Two possible issues come to mind with this problem.
1.) Most genset controllers come with a seperate engine speed controller. The end user usually has the ability to adjust the speed loop controller to optimize the response of the engine under step load conditions and steady state operation. The end user interface points are usually to the Proportional (P) the Integral (I) and the Derivitive (D) terms refered to the PID gains. You may have to open up the control box to get to this controller to adjust these PID gains. If you decide to open up the control box, disconnect the battery form the system to make sure you don't fry anything, or JUST BE CAREFUL. You are probably going to need to increase the Proportional (P) gain and/or the derivitive (D) gain terms to allow the engine speed controller to operate with a tighter response to changes in load. BEFORE YOU CHANGE ANYTHING, NOTE THE FACTORY SETTINGS SO YOU CAN GO BACK TO THIS SPOT IF YOU OVER COMPENSATE THE ENGINE CONTROL LOOP. If you set these gains to high the engine will "hunt" or oscillate during normal operation. If this occurs decrease these gains back towards there original settings until stable speed operation occurs.

2.) If you have a volt meter they usually come with a frequency measurment function. Check to make sure the generator frequency output is set to 60Hz (or 50Hz if you are in Europe). Again there is usually an end user adjustment spot to adjust the engine set point speed. If this is set to high, the controller may shut off after awhile due to the higher than normal operating speed. Again use caution since you will be probing high voltage and high power connections that could be deadly.

You can also contact the vendor you purchased the genset from and see if they can help, but this is usually a long and drawn out process that takes longer than the actually time it takes to fix the problem.

Hope this helps

By Wilton Anderson on 5 March, 2018 - 6:57 pm

My Guardian generac 15kw standby generator just had the same symptoms. I spoke to a generac certified repair guy and they mentioned something about some brushes might be damaged inside of the generator causing it to over speed. Does anyone know about this issue?