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Anonymous Poster

11Kv/415V Tranformer Neutral failure

08/13/2007 5:01 AM

Hello,

A tranformer was delivering over voltage i.e a range of 140 -320Volts/phase(r,y,b) when measured with a avometer and it keeps on fluntuating through the night damaging lots of gadjets at home. After series of trouble shooting, it was discoverd that the transformer earth(sec. side) termination point failed ie loose contact.The terminal point was corrected and the entire system balances out now giving a balance voltage range of 220-240Volt/phase.

Douggy.
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raspberry
Member

Join Date: Aug 2007
Posts: 8
#1

Re: 11Kv/415V Tranformer Neutral failure

08/13/2007 5:19 AM

This is standard for a loose neutral connection. When viewed with a three phase chart recorder, the three voltages appear to be fluctuating at random. One phase voltage increases, and the other drop etc.

The problem accentautes as load increases.

Raspberry..
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FKIA
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Join Date: Jul 2007
Location: Somewhere in the hills of Pennsylvania, I think.
Posts: 246
Good Answers: 4
#2

Re: 11Kv/415V Tranformer Neutral failure

08/14/2007 1:58 PM

O.K., I give up. What's the question?

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coconutpete
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Join Date: Feb 2007
Location: Suva Fiji Islands
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#3
In reply to #2

Re: 11Kv/415V Tranformer Neutral failure

08/14/2007 5:58 PM

I give up too but it may have something to do with fluntuation

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V.I.Abraham
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Join Date: May 2007
Location: Pune , India
Posts: 875
Good Answers: 42
#4

Re: 11Kv/415V Transformer Neutral failure

08/27/2007 7:35 PM

If your load is 3 phase balanced one,floating neutral does not cause neutral shifting or variation in phase voltage. The phenomena of neutral shifting happens when you have single phase un balanced load connected on three phase transformer with neutral and when the neutral get disconnected or develop loose contact in neutral line,the end results will be damage due to over voltage or under voltage in different phases. When you have single phase unbalanced loading on transformer neutral should be perfect otherwise voltage in each phase will increase or drop depend on type of unbalance loading.

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coconutpete (1); FKIA (1); raspberry (1); V.I.Abraham (1)

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