Protection Engineering Basics and Schemes Protection Engineering | Page 16

1.1.5 CT types as per applications:
When we are dealing with errors in CT we combined both
phase displacement and ratio error in composite error ,
We subdivided our CTs in classes as per their composite
errors and with respect to their application.
Protection CTs Classes
 5P
 10P
Metering CTs Classes
 0.1
 0.2
 0.5
 1
 3
 5
1.1.6 Accuracy limit Factor:
Accuracy limit factor is the ratio of maximum primary
current CT can bear without exceeding errors defined in
class to rated primary current
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