Phase Instantaneous Overcurrent Protection - GE 845 Instruction Manual

CHAPTER 4: SETPOINTS
Phase Instantaneous
Overcurrent
Protection
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 4-63: Phase Time Overcurrent Protection logic diagram
The 845 IOC element consists of the equivalent of three separate instantaneous
overcurrent relays (one per phase) - ANSI device 50P - all with identical characteristics. The
settings of this function are applied to each of the three phases to produce Pickup and Trip
flags per phase. There is no intentional "dead band" when the current is above the Pickup
level. However the Pickup accuracy is guaranteed within the current input accuracy of 3%
PROTECTION
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