Protective current transformer are required to operate over rated current many times and is frequently subjected to conditions greatly exceeding those which it would be subjected to as a measuring current transformer. When a current transformer is used to energize a protective relay, it must maintain its characteristic ratio up to some multiple of its rated current. This multiple maybe 5, 10, 20 or some even higher value and is known as the "Accuracy Limit Factor"(ALF). There for, the selection of Protective Current Transformer in relation to accuracy class and ALF require a close examination of relay characteristics and circuit conditions which includes the relay burden and the pilot wire lead burden.

Feature
Primary current from 100A to 5000A.
Protection grade: 5P10; 10P5; 10P10

Specifications       
Rated Frequency                                 50/60Hz 
Rated test voltage                    3kV AC. (1 min) 
Rated short-time thermal current(Ith)           60In 
Rated dynamic current, (Idyn)                   2.5Ith 
Rated voltage,(Um)                         0.72Kv AC.
Continuous overload,(Id)                            1.2In 
Operating temperature                    -10℃~50℃ 
Accuracy Limit Factor (ALF)                 5,10,20
Secondary current                                 5A/1A