distributionpanel main breaker

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lukuluku

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I am to design for my company a distribution panel that will supply power to the following quipment:
Air compressor 4 nos each having a starting current of 175A on a ( star/deltal starter) and a running current of 85A each.
1 nos vacum generator with a starting current of about 52A(DOL Starter)and a runing current of 18A and another vaccum generator with a starting current of 50A and a running current of 13A.
The 2 vaccunm generator are to be swithed on first while each of the compressors are to be switched on one after the other, 3 0f the compressors will works at a time while the 4th compressor is used as a spare.
I came up with the following design:
200A 4nos circuit breaker for each of the air compressors while I provided 100A each for the vaccum generator. I also provided for spare breakers one each of 200A and 100A.
For the "main" breaker to be used for the distribution panel I am thinking of using a 600A MAIN CIRCUIT BREAKER OR A 400A CIRCUIT BREAKER
The 400A main circuit breaker seems to be adequate but considering the starting currents for the compressor I would want to favour the use of the 600A circuit breaker.
the total steady state current for all the loads are (85+85+85+13+18)=286A.
Your advice on the best option for this design will be greately appreciated.
please not the equipments are to be run on a 3 phase 400v power supply.
 
Re: distributionpanel main breaker

sounds like you are not in the USA. hard to give you good advice on a foreign electrical system.

personally, I am always inclined to up the size of the main breaker rather than rely on interlocks to prevent starting of multiple units simultaneously, or the spare unit(s) always being spares. it is almost certain that at some point down the road the spares will end up not being spares anymore.

[ November 21, 2005, 03:49 PM: Message edited by: petersonra ]
 
Re: distributionpanel main breaker

Thanks a lot for your reply,
I actually wrote in from Nigeria thou the codes are difference but I have gained a lot from this forum .Besides I recent ly had a training in the USA. and a have fair knowledge of NEC. I hope to have more opionion on this design.
If there is any other site on the internet for Electrical design Engineers I would be glad to have the address.
 
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