What is CT accuracy class?
Accuracy Class of Current Transformer The accuracy class or simply class of measuring current transformer is 0.1, means the maximum permissible limit of error is 0.1%, more clearly, if we try to measure 100 A with a 0.1 class CT, the measured value may be either 100.1 or 99.9 A or anything in between these range.
What do you mean by class 5P10 CT?
If you see the specification or name plate of a protection class CT, you will find that it is given like 5P10. This CT can be interpreted as a protection class CT having an accuracy of 5% over a current range of 10 times of normal primary current rating.
What are the classes of current transformers?
There are three types of current transformers.
- Metering Class CT.
- Protection Class CT.
- Special Protection Class CT.
What does 0.2 CT mean?
0.2 and 0.2S refers to the accuracy of the Current Transformer. 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. And, with some increased error, the CT performance can be guaranteed from 5% loading.
What’s the difference between a X and a CT?
X represents the accuracy class. In case of CT’s used in protection it should replicate the current under fault ( that is high in magnitude) in the secondary. For example 5P10 class protection CT means when the current in primary is five times the rated (usually during fault) the secondary current error will be less than or equal to 10%.
What’s the difference between Class X and class PX?
Both Class X and Class PX are one and the same. Some times, it is also called Class PS. The latest IEC 61869 calls it Class PX. This is special class protection CT which has defined saturation characteristic and Knee point. Recommended for use especially for High Impedance differential protection.
What is the purpose of PS class CT?
PS class CT is used for differential protection of generator,motor and transformer. The manufacturer requires the following parameters for the design of the CT. How to Calculate Knee Point Voltage of Current Transformer?
What is the rating factor of a CT?
Multiples of Rated Current to which the CT can maintain its accuracy is called rating factor of CT. Typical rating factor is 1, 1.5, 2, 3, 4. Example: 500/5A CT with RF 2 CT will maintain it’s accuracy certification up to 1000A.