Figure 50: Differential Protection Blocking Mechanisms - GE P642 Technical Manual

Chapter 6 - Transformer Differential Protection
5 harmonic
th
Overfluxing detection
2nd harmonic
Inrush detection
No Gap detection
CT Saturation
External Fault
CT Supervision
Idiff > Is-HS1
Idiff > Is-HS2
V03114

Figure 50: Differential protection blocking mechanisms

120
&
1
&
Id biased
Start
Change Is 1 to
Is-CTS in
K2
restraint mode
K1
Is1
Is2
Id biased
Id biased
& Trip
delay
Idiff HS1 Trip
1
Idiff HS2 Trip
&
P64x
Idiff Trip
P64x-TM-EN-1.3