Sizing of bus capacity for parallel generators

The computation for the current should be multiplied again by 1.25. Its too high.

Enbr 77,

The 1.25 safety factor is based on NEC code requirement. Please see also Mc partland pratical electrical design.

Acer,

Each 1500 kVA generator can deliver 1805A. All 4 together give 4 x 1805A = 7220A.

You accounted for an additional 25%, thus 9021A. Why do you want to derate by 20% ?

Dear guest,

Derating is based on the generator site altitude and enclosure room temperature.

Thanks,

Acer

The bus bar rating in this case depends on number of outgoings and location of the outgoings.

I understand there are 4 outgoings.Each outgoing rating is 2500 Amps.There are 4 incomings each is rated for 1804.25 Amps.

If you arrange all the incoming on one side and all the outgoings on the otherside then bus bar rating should me 10000 amps.

if you arrange the incoming and the outgoing alternatively then bus bar rating can be 5000 amps.

similarly if you arrange all the incoming at the centre and outgoings ( 2 on either side) then also busbar rating can be 5000 amps.

Ramvinod,

My original design is based on your suggested concept, however, since cummins or ASCO can provide up to 10,000-12,000A I decided that it is good for the system considering bus expansion is quiet very hard when all equipment are already installed at site.

Thanks for your comments,

Acer