What is the accuracy class of CT?

What is the accuracy class of CT?

Accuracy class of current transformer is the highest permissible percentage composite error at rated current. The standard accuracy classes of current transformer as per IS-2705 are 0.1, 0.2, 0.5, 1, 3 and 5 for metering CT.

What is CT accuracy class 0.2 S?

An 0.2s accuracy class means that the measurement has an error rate of 0.2% over a range of 20 to 120% of the nominal current (In) and at a specific accuracy above 1% of In.

What is the meaning of accuracy class 0.5 S?

This is known as “Accuracy Class”. Class 0.5 means that the accuracy is 0.5% of the reading under full load and unity power factor, similar to 0.5% FS above, yet sets a standard for accuracy under lower (typical) loads and different power factor.

What is the difference between 0.2 and 0.2 S Class CT?

A 0.2S CT has a much higher accuracy than 0.2. Accuracy class of 0.2 means +/- 0.2 % error. But, the declared accuracy is guaranteed only between 100% & 120% rating. 0.2S class special CTs guarantee the declared accuracy +/- 0.2%, even with 20% loading.

What is PS class CT?

PS Class CT is also known as PX Class or simply Class X Current Transformer. It is special type of current transformer meant for protection purpose. Deviation in characteristics of CTs may lead to spill current in the secondary and even lead to actuation of protection element even under through fault condition.

How do you calculate CT burden?

Burden for Measuring CT:

1. Total burden of Measuring CT = Sum of Meters Burden in VA (Ammeter, Wattmeter, Transducer etc.)
2. Cable burden = I2 x R x2 L, where I = CT secondary current, R = cable resistance per length, 2L is the tro &fro distance of cable length L from CT to metering circuits.

What is meter accuracy?

Accuracy is how close the measurement is to the true value. In flow meters, that means how close the output of the meter is to its calibration curve. This is expressed as a percentage, e.g. ±1%. It means that any given reading can be in error 1% above or below the calibration curve.

What does accuracy class mean?

Accuracy classes are defined and used in IEC and ANSI standards. Typically, a class specifies accuracy at a number of points, with the absolute accuracy at lower values being better than the nominal “percentage of full scale” accuracy. Accuracy classes such as IEC’s 0.15s are a ‘special’ high accuracy class.

How is CT size calculated?

The CT’s are using for different -2 purposes in power system network. Vs = IFSC x (RCT + RL + nRR) (1) VS= Knee voltage IFSC= Fault current of secondary side CT RCT =Resistance of CT secondary RL =Lead resistance RN = Relay resistance When the offset waveform concept was introduced, (2) was used.

What are the accuracy classes of metering CT?

Standard Accuracy Class of Metering CT are 0.1, 0.2, 0.5, 1, 3 and 5. Each of these class have different maximum permissible current error. Let us now have a look at errors specified for these accuracy classes:

What are the standard accuracy standards for CT?

Class 1.0 (Standard) The standard grade CT meets or exceeds the accuracy class 1.0 limits. Accuracy: ±1.0% at 100% and 120% of rated primary current. Accuracy: ±1.5% at 20% of rated primary current. Accuracy: ±3.0% at 5% of rated primary current.

What are the accuracy standards for Accu-CT Transformers?

The Accu-CT ® series of current transformers (CTs) meet the accuracy requirements of two commonly used standards: ANSI/IEEE C57.13-2008 IEC 60044-1 Edition 1.2 Both of these CT accuracy standards describe the typical secondary output of a current transformer as 5 amps or 1 amp with an external burden.

What is the accuracy standard for C57.13?

The C57.13 standard has different accuracy classes: Class 1.2, Class 0.6, and Class 0.3. Each of these accuracy classes specifies the limit for the TCF as a percentage, so class 1.2 means the CT TCF must be within 1.2% of ideal at 100% of rated primary current.