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Understanding CTs and PTs in SLD

  1. Jan 28, 2016 #1
    Hi friends,

    i have quires that i cant count the CTs and PTs in the SLD. how many CTs for Protection and how many for Measuring or Metering and what is P2 means ?

    . n4tv2v.png
  2. jcsd
  3. Feb 2, 2016 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
  4. Feb 3, 2016 #3
    No idea on the P1 and P2 -- Point 1/Point 2 - for Polarity of the CTs is my only guess - since the polarity is "into" the HV side of the transfomer.

    The CT notation is #/ CTs and # / wires - you can wire three CTs in a Delta ( 3 wires out ) or a Wye (4 wires out).

    The measurement CTs (3) have a different spec than the protection CTs - because for measurement the accuracy in the nominal current range is most important - for the protection CTs they may need to provide accurate output at higher then nominal current ( 3 or more x) so the Protection CTs are typically heavier - larger core to prevent saturation at higher currents. I would consider the differential CTs part of the protection - but you do want them dedicated to the differential circuit to prevent errors.
  5. Feb 5, 2016 #4
    Thanks alot,

    if i have 02 CTs

    one is 1600:800:400/1

    2nd is

    15(10)VA 800:400:200/1A

    then what is the difference , one is 04 cores and 2nd is 01 core ? right ?
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