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Anonymous Poster #1

Number of Cores of CT

11/26/2017 7:46 PM

Dear Sirs,

Can sb tell me number of cores of Current Transformer for an incoming line on hydropower switchyard ie after Lightning Arrester? Is it three core for hydropower switchyard and five core for other intermediate substations?

Regards,

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#1

Re: Number of Cores of CT

11/26/2017 10:06 PM

42

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#2
In reply to #1

Re: Number of Cores of CT

11/26/2017 10:25 PM

I resisted the impulse to offer a similar answer.

The poor OP has never even heard of the manual.

I also enjoyed the training movie!

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Guru
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#3
In reply to #2

Re: Number of Cores of CT

11/26/2017 11:48 PM

Some days I just cannot hold back.

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#4
In reply to #3

Re: Number of Cores of CT

11/27/2017 12:01 AM

It is a target rich environment!

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#5

Re: Number of Cores of CT

11/27/2017 1:39 AM

The no. of cores (CT) is always decided by the protection and metering requirements for the subject feeder. Please check your protection & metering SLD.

Generally speaking, if you have no busbar in the switchyard and thus no busbar protection, 3-cores is all you require.

But, you never know you may add busbars in future.

Hence, it is better to go in for 5-core CT - 2-cores for busbar; 2-cores for feeder protection and 1-core for metering.

In case tariff metering is a requirement, you may also need one more core.

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#6

Re: Number of Cores of CT

11/27/2017 3:16 AM

<...Can sb ["somebody"] tell...> Yes - the equipment manufacturer can do this over the telephone.

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#8
In reply to #6

Re: Number of Cores of CT

11/27/2017 11:39 PM

Thanks! I had no idea what "sb" meant.

I'm frequently amazed at the abundance of questions about switchyard equipment, posted by people who apparently have no right to be inside the fence, or anywhere near. I certainly wouldn't want to be there when they are!

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#10
In reply to #8

Re: Number of Cores of CT

11/28/2017 10:07 AM

I'm amazed/appalled at the number of members who freely dispense information to obviously unqualified (usually anonymous) posters, knowing full well that they may have just handed them a loaded gun.

There was a time when I admonished our members to withhold dangerous information,

but was always ignored.

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#7

Re: Number of Cores of CT

11/27/2017 2:05 PM

Do you have a specification, if so what does it say?

Is this an existing plant, if so what do the as built drawings say?

Are you a consultant doing the design, if so what do your more knowledgeable colleagues say?

Is this a homework question, if so what do your coursework notes indicate?

There is no single right answer, if there were Engineering degrees would be much, much shorter and easier to get.

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#9

Re: Number of Cores of CT

11/27/2017 11:59 PM

The designer of the Plant has to give these details.This information can not be got from the forum.

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