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Join Date: Nov 2011
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Difference Between CT Magnetizing and Secondary Excitation Current

11/02/2011 1:01 AM

What is the difference between Current Transformer Magnetizing current and Secondary excitation current. Also how is the Excitation curve of a CT obtained?

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Anonymous Poster #1
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Re: Difference between CT Magnetizing and Secondary Excitation Current

11/02/2011 2:10 AM

N1/N2=I2/I1

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Re: Difference between CT Magnetizing and Secondary Excitation Current

11/02/2011 4:22 AM

Both mean the same, but with a subtle difference though.

Either is required for magnetising the core of the CT.

When the CT is in service, this magnetising or excitation current is drawn from the CT primary current itself.

But, when you want to test the CT for its magnetisation charecteristics, you may not have a current source to pump in the high accuracy limit currents.

So, generally an AC variable voltage is applied to the CT Secondary, keeping the primary open and the current drawn by the CT is measured and recorded. In this test procedure, the core magnetising or the excitation current is called the secondary excitation current. But, it is a misnomer to call it a "secondary" excitation current, as it is not the "secondary" that is excited, but the core.

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Re: Difference between CT Magnetizing and Secondary Excitation Current

11/05/2011 7:04 AM

@electricalexpert65 Thank you for your answer. It cleared a lot of doubts.

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