ABB REL 551-C1*2.5 Technical Reference Manual page 74

Instantaneous non-directional overcurrent
protection (IOC)
IOC--
IOC
BLOCK TRIP
TRP
TRN
xx01000176.vsd
Figure 20: IOC function block, phase + N with 3 phase trip
IOC--
IOC
BLOCK TRIP
TRP
TRL1
TRL2
TRL3
xx00000683.vsd
Figure 21: IOC function block phase with 1, 2, 3 phase trip
IOC--
IOC
TRIP
BLOCK
TRP
xx01000079.vsd
Figure 22: IOC function block, phase with 3 phase trip
IOC--
IOC
BLOCK TRIP
TRN
xx00000684.vsd
Figure 23: IOC function block, N + 3 phase trip
Chapter 5
Current
65