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Extended (?) CT ratio

Jam

Hi all,

I'm trying to calculate the Accuracy Limit Factor for some protection CTs but the ratio is specified as, for example, “5P20 extd. 1000%”… What does the “extd. 1000%” mean?

My first guess would be extending the 5% accuracy to 20x1000% = 200xIn under some condition, perhaps a specified burden.

The switchgear suppler is trying to help but is not desparately quick.

Thanks

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    No Idyn but Ith is 20kA/3s and the CT secondary current is low hence not so worried about sock removal (likewise at the relay).

    CTs made by TLEP (Chinese firm, not responding to email) on behalf of a reputable switchgear manufacturer.
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  • 0
    No Idyn but Ith is 20kA/3s and the CT secondary current is low hence not so worried about sock removal (likewise at the relay).

    CTs made by TLEP (Chinese firm, not responding to email) on behalf of a reputable switchgear manufacturer.
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