Coupling generator to transformer consequences
Coupling generator to transformer consequences
(OP)
Are there any consequences to coupling a generator to a large transformer? I have seen past postings that indicate this is a great way to eliminate inrush, but are there any factors that may be detrimental to the generator.
I am going to be supplying temporary power with (4) 2 MW – 480 Volt generators feeding a 13800 Volt bus. Each generator will have its own 2500 kVA transformer and a normally closed 15 kV switch on the high side. The main issue is that the 13800 side will be connected to a 30 MVA transformer. That is why we will start the first generator directly coupled to its transformer. When that generator is on line, we will sync the other 3 generators online.
I just want to make sure that there are not any issues on the generator alternator that I need to be aware of by energizing the transformers this way. I will slow down the soft starting of the voltage regulator to try to cut down on voltage overshoot.
Have also enclosed a simple one-line.
Any suggestions or comments are greatly appreciated.
I am going to be supplying temporary power with (4) 2 MW – 480 Volt generators feeding a 13800 Volt bus. Each generator will have its own 2500 kVA transformer and a normally closed 15 kV switch on the high side. The main issue is that the 13800 side will be connected to a 30 MVA transformer. That is why we will start the first generator directly coupled to its transformer. When that generator is on line, we will sync the other 3 generators online.
I just want to make sure that there are not any issues on the generator alternator that I need to be aware of by energizing the transformers this way. I will slow down the soft starting of the voltage regulator to try to cut down on voltage overshoot.
Have also enclosed a simple one-line.
Any suggestions or comments are greatly appreciated.






RE: Coupling generator to transformer consequences
You can bring up the transformer with a generator, but you can't have any loads connected to the transformer while it is coming up, obviously.
The possible synchronizing scenarios will have to be carefully thought out and appropriate interlocking used to avoid closing in out of synch.
RE: Coupling generator to transformer consequences
There will NOT be any loads on the system. We will bring the first generator on with its breaker closed and powering the transformer on startup. Once the generator is stable, the other generators will be synced and paralleled. When all four are on line, the load will be manually added.
We have all the synchronizing and load sharing controls already in place. Have done numerous jobs paralleling jobs. Just haven't started with a direct couple to a transformer this large.
Want to make sure it won't damage the alternator.
RE: Coupling generator to transformer consequences
There are others around here who have more experience with this than I do, so maybe they will be able to add something.
RE: Coupling generator to transformer consequences
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RE: Coupling generator to transformer consequences
Thanks for all the responses.
RE: Coupling generator to transformer consequences
Keith Cress
kcress - http://www.flaminsystems.com
RE: Coupling generator to transformer consequences
RE: Coupling generator to transformer consequences
This is a temporary power solution only. Not permanent. Our generators are already equipped with the paralleling gear and breakers on them. This will only be used as a standby system. If the main utility fails, the bus will be dead. We will manually start the first generator with its breaker closed and power up the transformer. Then the other generators will be synced and paralleled to the bus. Then the load will be added by a switch on the load side of the 30MVA.
I guess my main question is if this will be detrimental to the generator / alternator by energizing the transformer this way.
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