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anandbhushan
Participant

Join Date: Sep 2010
Posts: 1

Unbalance in Power System

09/15/2010 2:44 PM

we are having 10/12.5 MVA, 132/11KV, %impedance 8.12%, star/star with nutral ground on both sides. this transformer is loaded with two single phase transformers in addition to three phase transformers, one is connected between R and B phase having 3MVA, 11/3.45KV, %impedance 8.237% No. of phases 01 and another is also connected between R and B phase having 4MVA, 11/3.6KV, %impedance 6.82% No. of phases 01. what may be the unbalance of the system and how to calculate it.
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mountk2
Power-User

Join Date: Jun 2010
Posts: 348
Good Answers: 10
#1

Re: Unbalance in Power System

09/15/2010 4:58 PM

It is not a matter of imbalance or as to how to calculate it, rather the scheme is a conceptual failure.

star- star connection is strictly meant for balanced loads, effect of unbalanced loading is that neutral point shifts resulting in dangerous overvoltages.

Connection of 3+4 MVA transformers on R-B phases, both neutral points grounded,

It is an immidiate distruction !!!

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Anonymous Poster
#2
In reply to #1

Re: Unbalance in Power System

09/16/2010 9:27 AM

But 3MVA 11KV/3.45KV single phase transformer connected between R and B phases is loaded on 10/12.5MVA, 132KV/11KV transformer (which is having tertiary winding in delta connection) from last 10years.
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