GE Multilin 850 Instruction Manual page 327

CHAPTER 4: SETPOINTS
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 4-77: Counter Based Timed Undervoltage Protection logic diagram
Logic Explanation for System Scenarios
For the logic shown in the preceding logic diagrams, the sample system scenarios are
explained in Case1, 2, and 3 respectively.
Case 1
Behavior when the element trips by entering the operating region of the configurable
characteristic curve. The element operates due to the trip time defined by the curve. The
sample settings and the expected behavior are shown here.
Curve Settings:
Pickup:
Dropout:
Voltage Drops:
Figure 4-78: System behaviour from Case 1
As shown in the red characteristic curve
0.90 x VT
105.5 % of PKP (0.95 x VT)
2
PROTECTION
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