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Active Contributor

Join Date: Oct 2008
Posts: 23

Shortcircuit current

10/19/2008 10:45 AM

Dear sir,

In my case, The 11 kv/433 V ,3600 KVA transformer shortcircuit current is 76KA.So i have selected ACB rated for 6000a,Ish=100KA which is going to feed for PCC having 3 nos of 250KW motor , 1 no chiller compressor of capacity 586 kw , 2nos of pumps of capacity 90KW and 2 nos of cooling tower motor of capacity 110KW.All are running with 80%.How to i have to select the MCCB with Ish for PCC incomer and outgoing MCCB rating the loads mentioned as above.What are all the things to be taken for calculation.Pl explain in details.........

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Guru

Join Date: Jun 2007
Location: chennai,India
Posts: 592
Good Answers: 19
#1

Re: Shortcircuit current

10/19/2008 1:35 PM

On casual reading the the connected load does not increase beyond 2000 kw.What is the diversity factor ?.In my opinion 3600kva trafo is over rated.In india Generally we select 2500 kVA transformer as maximum for LT Distribution.if the load is beyond 2500 kVA , we distribute the load to two transformers.

May be I can help you if you give all the relevant particulars.

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Ramesh,Freelance Electrical/automation Consultant
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Active Contributor

Join Date: Oct 2008
Posts: 23
#2
In reply to #1

Re: Shortcircuit current

10/20/2008 12:58 AM

Dear sir,

We will be going with 3600 KVA transformer with a special approval.Load factor is 50% since one transformer failed the adjacent transformer will share the load of the failed one.

I want to share something ie as per the IS standard max capacity of distrn transformer is 1600 KVA ( IS:10028 part 1).But they are allowing upto 2500 KVA ,reason behind that one is availability of test facilities and high rating switch gears.

Now a days switchgears and test facilities are available for 3600 KVA transformer switch gear items.So we have to revise the IS standard for 3600 KVA transformer.

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