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Urgent (diesel engine alternator)


Wondewonde's Avatar
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02-10-13, 06:35 AM   #1  
Urgent

18kvA generator engine goes off while I remove one terminal of generator. Also in normal operation the engine goes down almost to shut down and then goes up even without load.Both syptom happening in different time. In my understanding diesel engine alternator will charge the system once the engine starts. What do U suggest the problem?



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Last edited by Wondewonde; 02-10-13 at 06:45 AM. Reason: one figure is missing
 
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02-10-13, 06:55 AM   #2  
Clarifying: You have the two systems you're talking about - the generator which the engine drives to provide electricity for say a van or a heater or lights, etc. and the alternator on the engine that charges the battery that starts the engine?

If that is correct, the alternator would charge the battery that starts the engine. That system would be tripped on (or could be) when a demand is present for the generator to run. This would be like when land line electricity is lost and the generator engine starts up to fill in. The latter is somewhat automated and you see that in hospitals a lot.

Other backup or primary systems are manual startup or run all the time for periods of time.

 
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02-10-13, 07:21 AM   #3  
The diesel engine that drive 18KVA electric motor 1- will shut down while one battery terminal removed. 2- while engine working it goes down almost to shut down and then goes up to normal working rpm, and sometimes shut down the engine even at no load.

 
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02-10-13, 07:24 AM   #4  
Is that an automated startup where it's used as a backup. It would then start on its own to supply electricity when another source fails?

 
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02-10-13, 07:35 AM   #5  
not at all. There is two generator one 40KVA and the other is the faulty one 18KVA and both are connected to a change over switch. It is shifted manually in 12 hour interval

 
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02-10-13, 07:41 AM   #6  
Marbobj, does the working principle support while battery terminal removed the engine should shut down??? this problem also happening in 6.5Kw generator

 
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02-10-13, 08:25 AM   #7  
I'm not exactly sure what you are doing there but technically once an engine is started you don't need the battery connected as the alternator will supply power but the battery should be left connected to hold the regulated voltage stable.

Removing the battery can cause the alternator voltages to spike which is not particularly healthy to electronics and control modules.

 
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02-10-13, 09:07 AM   #8  
Tnx PJmax. In case of vehicle removing battery terminal will not shut down the engine even on electronic controlled cars. But in case of generator am expecting it might be the symptom of another problem because this generator engine sometimes will goes down from set rpm even at no load.

 
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02-10-13, 10:07 AM   #9  
It depends a lot of what you have set up there. The engine alternator can supply power to the battery only, then that current will go to a solenoid type shutoff on the fuel injection pump. If the power to that solenoid is interrupted by the means you're describing, or if the alternator is malfunctioning, then the engine would shutdown. Some automotive designs need a battery in the circuit for the engine to run.

If you have an older type of diesel where the shutoff is manual through say the throttle position directly to the pump, then the power interruption would make no difference and the engine would keep running.

If you have a setup where the power to the solenoid is picked off the current directly from the alternator going to the battery, then the alternator, if working properly would keep the solenoid open and the engine would continue running. That may or may not be the case with yours.

I was asking about the automated startup of yours in case a relay responsible for the startup and shutdown, depending on an alternate source of power failing, may be malfunctioning and shutting the system down.

 
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