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Translation of CT classes between IEC and ANSI
2

Translation of CT classes between IEC and ANSI

Translation of CT classes between IEC and ANSI

(OP)
I need some way of translate IEC CT class 0,2 to an ANSI Class C??? are there any standard way of doing this?

RE: Translation of CT classes between IEC and ANSI

You're trying to compare a metering accuracy class to a protection accuracy class. The closest IEEE accuracy to the IEC 0.2 class would be the IEEE class 0.15 or 0.3.

IEC defines the burden as a VA, i.e. Cl. 0.2 - 15 VA. IEEE defines burden as impedance, i.e., 0.3B1.8 (up to 1.8 ohms).

RE: Translation of CT classes between IEC and ANSI

Here is a rough equivalence for selection of Instrument transformers (CTs & PTs) by application in accordance with IEC and equivalent with ANSI/IEEE.

---------------------------------------------------------------------
Application                                    IEC Class  ANSI Class
---------------------------------------------------------------------
Precision measurement & calibartion           0.1       0.3
Accurate pwr & tariff metering                    0.2       0.3
Tariff & accurate measuring instruments      0.5       0.6
Industrial Meters: V, I, P, meters                 1         1.2
Ammeter or volmeters, overcurrent/V relay   3        1.2
Current Transf. protective cores              5P,10P     C,T
----------------------------------------------------------------------
SOURCE: ABB Switchgear Manual, 10th edition.

RE: Translation of CT classes between IEC and ANSI

cuky2000-

That info is slightly dated, whereas the IEEE equal for the first 2 IEC classes listed is the 0.15 class.

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