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Join Date: May 2009
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CT IN SECONDARY

06/02/2009 5:26 AM

HI ALL,

WHY GENERALLY WE ARE PUT 3 CT'S IN SECONDARY?

YA 0NE IS FOR METERING OTHER ONE FOR PROTECTION .

WHAT IS THE REQUIREMENT OF THIRD CT?

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Power-User

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#1

Re: CT IN SECONDARY

06/02/2009 5:47 AM

SHHHHHHHHHHHHHHH! <Burp>

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Join Date: Apr 2008
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#2

Re: CT IN SECONDARY

06/02/2009 9:17 AM

First, it seems you are describing a three phase power feed of some kind. Each phase can provide a different amount of power so using a single CT for metering would assume an equal amount of power consumption on the other two. That would be a bad assumption.

For the same reasons, picking an arbitrary phase for protection dosen't make since. Perhaps you have not examined the connections closely enough. All three CT's would or could be used for either purpose mentioned. Unbalanced consumption of power is quite common even though attempts are made to avoid it. But when it comes to metering, you can be sure that every KWH is captured using all three CT's.

Lastly, lower your voice (tone) by turning off the CAPs LOCK button

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#3

Re: CT IN SECONDARY

06/02/2009 8:39 PM

Generally, in the protection of the power line, there will be 3 CT install in each phase. These CT are for as follows:

a) 1 CT for Metering

b) 1 CT for Protection such as over Current

c) 1 CT for Differential Relay and Restricted Earth Faults.

Some may use the 3rd CT for Quality Power Analyzer

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Join Date: May 2009
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#4
In reply to #3

Re: CT IN SECONDARY

06/03/2009 12:30 AM

Thanks ,Simon Wan............

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