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Anonymous Poster #1

OLTC Selection

09/13/2019 2:24 AM

Dear sirs,

OLTC is kept on high voltage side so that lesser current can be handled with ease.

For 132kV / 220 kV autotransformer, OLTC is kept. How is its voltage class and current is selected. Similarly, how to read the step capacity diagram?

Regards,
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HiTekRedNek
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Join Date: Oct 2006
Location: 44.56024"N 15.307971E
Posts: 8277
Good Answers: 270
#1

Re: OLTC selection.

09/13/2019 6:26 AM

Here is a link that explains how OLTC works.With video.

https://electrical-engineering-portal.com/4-essential-features-of-transformer-on-load-tap-changer-oltc

Lots more info on google;I suggest self study if google is available to you.

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Anonymous Poster #1
#2
In reply to #1

Re: OLTC selection.

09/14/2019 9:38 AM

Rated through current an step calculation for OLTC can be done from original transformer data. How?

The transformer is 50 MVA and it is 132/220 kV step up transformer.

Regards,
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Anonymous Poster #1
#3
In reply to #2

Re: OLTC selection.

09/14/2019 9:46 AM

I mean rated through current and step voltage...
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rwilliams
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Join Date: Jul 2016
Posts: 1367
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#4
In reply to #2

Re: OLTC selection.

09/14/2019 2:37 PM

Some of the older nameplates have the current rating of each step. The OLTCs I’m familiar with are on the secondary side, and use saturable reactors to boost or buck the output voltage. They don’t directly handle the transformer winding current.

The transformer MVA rating should be maintained at the lowest designed tap (highest if indeed primary On Load Tap Changer) and at the lowest design voltage, as marked on the nameplate.

So the amperes allowed on the secondary will always be stated on the nameplate, regardless of tap position. You can use the rated MVA and rated voltage to calculate the amperes, if no other information is available.
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