Generator Voltage Dip
Generator Voltage Dip
(OP)
Our client reported that they are experiencing an unpredictable and irregular voltage dip with their power supply. They have their own power plant using diesel engine generators. On a particular single-unit operation, they reported that the dip occurs once a month, after two months and twice a month. The genset is still new. It was a brand new unit started-up and operated 6 months ago. The dip occurs only on this new unit.
The voltage dip, according to the report, occurs for a duration of about one second. However, the motor loads stopped/tripped off. They observed that the voltage meter almost registered "zero" during the dip and recovers. One report indicated that after the recovery of the voltage, the meters registered 58Hz and 450V. (The system is 3-phase, 480V, 60Hz.)
Has anybody experienced such occurrence? What is/are the possible causes of this dip?
Any inputs are appreciated. Thanks.
The voltage dip, according to the report, occurs for a duration of about one second. However, the motor loads stopped/tripped off. They observed that the voltage meter almost registered "zero" during the dip and recovers. One report indicated that after the recovery of the voltage, the meters registered 58Hz and 450V. (The system is 3-phase, 480V, 60Hz.)
Has anybody experienced such occurrence? What is/are the possible causes of this dip?
Any inputs are appreciated. Thanks.






RE: Generator Voltage Dip
RE: Generator Voltage Dip
RE: Generator Voltage Dip
RE: Generator Voltage Dip
Thank you very much for the insights. I will follow your advice. Will let you know the results. I really appreciate it.
RE: Generator Voltage Dip
Hi Gene!
I have some question: How many generators are connected?
There are feeding the same bus?
I said this because, when one generator (connected in parallel with others generators)loose (for any reason) the excitation current; the terminal voltage do not fall to zero immediatly, Why? because the gen when loose the excitation, behave like a Induction Generator. I mean the generator will absorb the reactive power that need and the speed down (slip).
Excuse my English!
Regards!
RE: Generator Voltage Dip
RE: Generator Voltage Dip
The unit in question is running as single unit - not synchronized with the other units. There are 3 units one of which is new where the problem occurs. Synchronizing is used when transferring the load from one unit to another.
jbartos:
I agree with you. Actually, the operators are logging the volts, amps and kw hourly. However, since the dip as reported is unpredictable and lasts only for a second, they have no record on the exact values during the actual dip.
Thanks to both of you.
RE: Generator Voltage Dip
Regards
RE: Generator Voltage Dip
RE: Generator Voltage Dip
You should also check the rotating rectifier diodes and also the semicondutor fuses, if any in that ckt for any damages due to dynamic forces.
RE: Generator Voltage Dip
Are you the supplier of this unit? I suppose this unit is still under warranty. Then, the supplier should provide the services to determine the problem and the appropriate solution.
In addition to previous suggestions, I noted from the information you provided, "One report indicated that after the recovery of the voltage, the meters registered 58Hz and 450V".
If the problem is on electrical/generator side, the frequency/speed of the engine should have remained stable during voltage dip. Intermittent overloading or high starting currents may cause the voltage to dip more so if the engine can't respond fast enough. Please check engine side also, governor gain setting, fuel lines, etc. And be sure no overloading.
Regards