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CT

CT

(OP)
What is meant by 5p10 in an ct.

RE: CT

This is the designation for current transformer per IEC Standard 185 as follow:

 “10”…………….Declare composite error at accuracy limit primary current (Ex 2.5 & 10)
“P”………………Indicates the CT classification (Ex. P=Protection, M=Metering, TP)
“15”……………..Rated secondary reference voltage (Ex. 10,15,20, 30, 75).

The rate accuracy factor  other than 20 should be indicated in the designation.

NOTE: There is an equivalence ANSI designation (Ex C100 to C800)

RE: CT

two questions:
1 - cuky - should your "15" be "5"
2 - can you remind me how we determine the rated burden (needed to transform the voltage into a current).

RE: CT

Electricpete,

Thanks for your observation, I mixed-up the above numbers. Please correct as follow:

"5"....Composite error
<5% at rated accuracy limit primary current.

"10"...Rate accuracy limit factor
i.e. Overcurrent = 10 x rated normal current.

The prefer way to express the burden in IEC generally is given in VA and is calculated as follow:

      Sb = Zb.I2ns


Were:
Sb= Burden (VA)
Zb= Burden (Ohm)
Ins=Rated secondary current(amp).


RE: CT

cuky'--  Gnarley super- and sub-script tags!   For the rest of us, see the 'Process TGML' link.
 

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