Generator hunting problem
Generator hunting problem
(OP)
Hi,
I have a 220KVA Iveco generator with Deep Sea Electronics Model 521 Automatic start and Iveco Aifo Speed Control Unit installed. This then goes to a Star Delta control box that runs a 55KW motor on a granulator (for the plastic industry. It is a Blackfiars HD67 granulator)
I am having a problem with the generator. It seems to be hunting all the time in time with the granulator working. I have checked for fuel leaks and made sure that all the connections are tight. I am about 100% sure that the problem isn't an air leak in the fuel.
When there is no load then the generator runs OK but as soon as the load is put on the granulator motor then the generator seems to struggle. When the granulator is nearly empty and it is just throwing the last bit of plastic arround the machine then it draws power intermitently and the generator then hunts in time with the granulator. (at this point it isn't drawing many more amps than at idle. between 30 and 60) Eventually it just stops (sometimes after 3/4 hour sometimes 1/4 hour) and then sometimes needs bleeding to start again but not all the time. I suspect this is because the hunting causes a vacum in the pump and is not the actual cause of the problem but a symtom.
We are now stuck so any thoughts on this would be most appreciated.
Cheers
Lenny
I have a 220KVA Iveco generator with Deep Sea Electronics Model 521 Automatic start and Iveco Aifo Speed Control Unit installed. This then goes to a Star Delta control box that runs a 55KW motor on a granulator (for the plastic industry. It is a Blackfiars HD67 granulator)
I am having a problem with the generator. It seems to be hunting all the time in time with the granulator working. I have checked for fuel leaks and made sure that all the connections are tight. I am about 100% sure that the problem isn't an air leak in the fuel.
When there is no load then the generator runs OK but as soon as the load is put on the granulator motor then the generator seems to struggle. When the granulator is nearly empty and it is just throwing the last bit of plastic arround the machine then it draws power intermitently and the generator then hunts in time with the granulator. (at this point it isn't drawing many more amps than at idle. between 30 and 60) Eventually it just stops (sometimes after 3/4 hour sometimes 1/4 hour) and then sometimes needs bleeding to start again but not all the time. I suspect this is because the hunting causes a vacum in the pump and is not the actual cause of the problem but a symtom.
We are now stuck so any thoughts on this would be most appreciated.
Cheers
Lenny
RE: Generator hunting problem
If you have to bleed air then there is a leak or you are running out of fuel. Whenever the engine is turning there should be a vacuum in the fuel pump. That's how it sucks up the fuel. Go figure.
After you fix that, check the fuel stop setting of the governor. If the engine has been worked on be someone not familiar with generators the speed may have been set with the fuel stop adjustment rather than the speed adjustment. That will result in the engine pulling down under load.
No load speed should be set 3% above nominal frequency.
Bill
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"Why not the best?"
Jimmy Carter
RE: Generator hunting problem
RE: Generator hunting problem
Is the engine "making oil"? You may have a damaged diaphragm in the engine mounted fuel pump. A symptom of a damaged diaphragm may be fuel in the crank case and an increasing oil level. But not always.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator hunting problem
RE: Generator hunting problem
Erratic slow downs that I have encountered are usually fuel related. Have the fuel filters been changed lately?
An anecdote; A worker filled the fuel tank on a small diesel generator with fuel from a tank with a lot of standing water.
He got a couple of quarts of water into the fuel tank. The filter plugged and the set stopped. He correctly diagnosed the problem as a plugged fuel filter and changed the filter. The fuel pickup was still sucking water. The new filter plugged up immediately. He had just changed the filter so he "knew" that the filter was good. He then suspected the oil pressure switch and destroyed it. The over temp was the next to go. I forget what all was on the set, but he managed to destroy everything, including the remote start. Finally he found the water, cleaned the tank, changed the filter and started the set. In the next few months it turned out that the safety stops were not needed. An oil line broke.No problem, the set eventually stopped on its own. Over temp, stopped on it's own. Another oil leak, no problem it'll stop.
When the set could not be started at all, it was sent to the dealer for repairs.
The dealer evaluated the damages and then asked what our tax situation was. The repairs would cost $4600. If we were not in a position to write the repairs of against taxes a new motor could be supplied for $4000.
The moral is; Just because you have changed a filter, the fuel may be still contaminated.
This really sounds like a fuel related problem. But the motor may be failing, or you may have a cable going bad.
If you have an ammeter, see if the amps are going up above the rated output of the set when it slows down.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator hunting problem
RE: Generator hunting problem
I don't think that you have told us the voltage or frequency yet
What make of engine is driving the generator?
What type of governor? Mechanical, Electronic?
By the way, if it's electronic, check the wiring to the induction pickup on the bell housing near the flywheel.
I have had connectors go bad. A loose or out of adjustment proximity pick-up may cause strange actions.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator hunting problem
It most likely has an electronic governor.
I would check the stabilty gain first and then the magnetic pickup for metal filings.
Then I would troubleshoot the governor controller and actuator. Assuming all wire terminations are secure.