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Anonymous Poster #1

Transformer Selection

09/08/2011 7:01 AM

We estimate a peak load of 3500 KVA in our new plant. Power supply is from 33KV grid. Shall we opt for one no. 33/0.433 KV, 4 MVA transformer or two nos 33/0.433KV, 2MVA transformers ? If the second option is adopted, there will be no need to operate the transformers in parallel in future. Which option is more economical without compromising safety & reliability, considering cost of transformer, busduct, HT & LT breakers, keeping in mind LT current rating & short circuit rating ?

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Guru
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#1

Re: Transformer Selection

09/08/2011 8:59 AM

2 X 4MVA to give redundancy to the system.

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#2

Re: Transformer Selection

09/08/2011 10:48 AM

the cost of those transformers should be take in account! 4MVA covers the peak load and you get 0.5MVA extra (is not much but you can in the future plug a few more machines) 2 transformers will rise in others costs as well, such construction and maintenance of facilities, between others still. thats my choice- nº1

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#3

Re: Transformer Selection

09/09/2011 1:37 AM

Since 3.5 MVA is peak load, you can also opt for say 2x2.5 MVA or 2x2.0 MVA depending on base continuous load. Such an arrangement ensures base loads are met, in the event of failure of one of the transformers.

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Power-User
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#4

Re: Transformer Selection

09/09/2011 4:38 AM

be careful in choosing your KV and MVA...you might end up with high fault current level...choose the right kV and MVA...

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Power-User

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#5

Re: Transformer Selection

09/09/2011 10:59 AM

since you do not wish/need to use the transformers in parallel - having 2 is better to limit your fault levels . . . you should still have a bus coupler so if you are operating at less than half load you may save on the fixed losses of one transformer . . .

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Guru
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#6

Re: Transformer Selection

09/09/2011 11:52 PM

Even though the initial expenditure will be more I strongly recommend for 2 MVA transformers with bus coupler arrangement as it will be much more convenient and maintenance . There will be saving in recurring losses and can avoid power outing for preventive maintenance and all the more essential if a continues process industry which needs un interrupted power supply..

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