Grounding Multi-Ratio CTs

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Bugman1400

Senior Member
Location
Charlotte, NC
mivey said:
You don't ground polarity. Polarity is the smaller number and goes to the instrument (X1 for your example). The higher of the used numbers gets grounded (X2 for your example).
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Whether you ground the polarity side or the non-polarity side is a matter of application. Some devices use the non-polarity instead.....metering comes to mind since many times it uses the opposite side that of the relaying. There is also the off-chance that the CT was incorrectly installed in reverse.
 
mivey

mivey

Senior Member
Bugman1400 said:
Whether you ground the polarity side or the non-polarity side is a matter of application. Some devices use the non-polarity instead.....metering comes to mind since many times it uses the opposite side that of the relaying. There is also the off-chance that the CT was incorrectly installed in reverse.
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True enough.:thumbsup: I was in substation mode.
 
ATSman

ATSman

ATSman
Location
San Francisco Bay Area
Occupation
Electrical Engineer/ Electrical Testing & Controls
Phil Corso said:
Sunny,

X1-X2 has, say=40 turns; X2-X3=30; X3-X4=20; X4-X5=10! Always maintain the ground-connection at X5! Then, connect burden-devices between X1, and X5!

Thus, Max turns-ratio, available, between X1-X5 is 100:1!

Example 2: you want 50:1 ratio, simply short terminals X2-X3-X4!

Example 3: you want 10:1 ratio, simply short terminals X1-X2-X3-X4!

And, you must never leave turns open-circuited!

Regards, Phil Corso
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Phil
Looks like you are thinking of a different device;

http://www.schneider-electric.us/en/faqs/FA111406/
 
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rian0201

Senior Member
Location
N/A
mivey said:
You don't ground polarity. Polarity is the smaller number and goes to the instrument (X1 for your example). The higher of the used numbers gets grounded (X2 for your example).
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i disagree this depends on your application.. you can ground either X1/X2, in my example, if the use of such CT demands it and as long as you only ground one point..


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rian0201

Senior Member
Location
N/A
Bugman1400 said:
Whether you ground the polarity side or the non-polarity side is a matter of application. Some devices use the non-polarity instead.....metering comes to mind since many times it uses the opposite side that of the relaying. There is also the off-chance that the CT was incorrectly installed in reverse.
Click to expand...

i agree with this


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