4.2 Differential Protection
437
7UT613/63x Manual
C53000-G1176-C160-2
Figure 4-2 Restraining influence of 2nd harmonic in transformer differential protection
I
diff
differential current = |I
1
+ I
2
|
I
NObj
Rated current of protected object
I
fN
Current at rated frequency
I
2f
Current at double frequency