GE B30 UR Series

GE Multilin B30 Bus Differential System 9-11
9 THEORY OF OPERATION 9.6 OUTPUT LOGIC AND EXAMPLES
9
Figure 9–10: EXTERNAL FAULT EXAMPLE
836735A1.CDR
The bus differential protection element picks up due to heavy CT saturation
The CT saturation flag is set safely before the pickup flag
The element does not maloperate
The directional flag is not set
0.06 0.07 0.08 0.09 0.1 0.11 0.12
-200 -150 -100
-50
0
50
100 150 200
~1 ms
Despite heavy CT saturation the external fault current is seen in the opposite direction