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siegfredo c. tabanag
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% Impedance In 3-Phase Transformer

10/20/2012 10:48 AM

What will be the percent impedance to be used in computing the Short Circuit current of a 300 KVA three phase transformer connected Wye-Delta from three single phase transformers banked together. 13.2KV/240V: 2.8 % for each transformer: 100 KVA each
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nobodysomebody47
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#1

Re: % IMPEDANCE IN 3-PHASE TRANSFOMER

10/20/2012 11:43 AM

Check these

% impedance calculation

impedance vs. Percent impedance
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Joshi
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#2

Re: % Impedance In 3-Phase Transformer

10/21/2012 6:07 AM

"connected Wye-Delta from three single phase transformers banked together."

Is that true? Is it because you have these transformers lying around or bought from discount/bargain deals? Why were the transformers sized this way, in the first place? Is this considered better/best? Looking forward to learning something new/esoteric theory.
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siegfredo c. tabanag
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#3
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Re: % Impedance In 3-Phase Transformer

10/21/2012 10:09 AM

in the Philippines,it is our practice to banked 3 identical single-phase transformers to supply three phase power to a building. this is to standardized sizes and flexibility in case one of the transformers will be damaged, we can still operate temporarily in open delta connection using two transformers only.I don`t know in your own country which is more developed than mine. Thanks. .
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Joshi
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#4
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Re: % Impedance In 3-Phase Transformer

10/21/2012 10:14 AM

Thank you siegfredo c. tabanag. You have a good point there.
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siegfredo c. tabanag
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#5
In reply to #4

Re: % Impedance In 3-Phase Transformer

10/21/2012 8:10 PM

Thanks also!
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Joshi
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#6
In reply to #5

Re: % Impedance In 3-Phase Transformer

10/21/2012 10:19 PM

This may assist you.

Transformer Impedance Calculation - All About Circuits Forum
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Joshi
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#7

Re: % Impedance In 3-Phase Transformer

10/23/2012 2:49 AM

Does not the name plate on the transformer, show this figure?
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PWSlack
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#8

Re: % Impedance In 3-Phase Transformer

04/23/2025 5:05 AM

Does it not say in the installation and maintenance manual that came with it?

Does it not say in the commissioning records that were generated before placing it into service?

Does it not say in the periodic condition assessment testing records that satisfy both the local insurer and the local fire brigade?

If not, then a telephone call to the original manufacturer is the next, urgent, step.

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