Recommended Ct Classes - GE MiCOM P40 Agile Technical Manual

Chapter 16 - Current Transformer Requirements
2

RECOMMENDED CT CLASSES

You can use Class X current transformers with a knee point voltage greater or equal to that calculated. You can
also use class 5P protection CT. These have a knee-point voltage equivalent, which can be approximated from the
following calculations:
´ ALF)/I
V = (VA
k
where:
V = Knee-point voltage
●
k
● VA = Voltampere burden rating
ALF = Accuracy limit factor
●
I = CT nominal secondary current
●
n
R = CT resistance
●
CT
420
´ ALF ´ I
+ (R )
n CT n
P543i/P545i
P54x1i-TM-EN-1