Power Distribution: Motor Starting
Power Distribution: Motor Starting
(OP)
I need some help to settle an argument...
I have a power distribution network with secondary selective switchgear (i.e. two incoming feeders to the switchgear with an open bus tie breaker).
The the main distribution switchgear is fed by generators synchronized with a feed from the grid and there are some large motors attached to one bus of the secondary selective switchgear a couple of levels below.
My question is, is it likely to be more difficult to start the motor when the switchgear it is fed by has both incomers connected and the bus tie breaker open or with a single incomer connected and the bus tie breaker closed (assuming all other factors stay the same)?
Let me know if you need more info. I'll be grateful if anyone can help me to settle the argument.
I have a power distribution network with secondary selective switchgear (i.e. two incoming feeders to the switchgear with an open bus tie breaker).
The the main distribution switchgear is fed by generators synchronized with a feed from the grid and there are some large motors attached to one bus of the secondary selective switchgear a couple of levels below.
My question is, is it likely to be more difficult to start the motor when the switchgear it is fed by has both incomers connected and the bus tie breaker open or with a single incomer connected and the bus tie breaker closed (assuming all other factors stay the same)?
Let me know if you need more info. I'll be grateful if anyone can help me to settle the argument.






RE: Power Distribution: Motor Starting
If the two sources are from different busses, you will get circulating current when you close the tie breaker and this should be looked at too. If the effects are relatively minor, then my initial comments of easier motor starting with the 2 paralleled sources still apply.
RE: Power Distribution: Motor Starting
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If we learn from our mistakes I'm getting a great education!
RE: Power Distribution: Motor Starting
Unless of course you pick the bus with the generation paralleled with one incoming feeder. This would be a better choice.
RE: Power Distribution: Motor Starting
The impedance is the same regardless of whether the motor switchgear is fed with both incomers connected and the bus tie breaker open or with a single incomer connected and the bus tie breaker closed.
Thank you.
RE: Power Distribution: Motor Starting
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If we learn from our mistakes I'm getting a great education!
RE: Power Distribution: Motor Starting
However, the above does not mean the motor is more difficult to start. If it gets enough voltage applied then it will still start just fine.
But then, maybe I don't understand how you are describing your system...