GE 745 Instruction Manual page 168

S4 ELEMENTS
5.6.8 Restricted Ground Fault

W1 RESTD GND [
FAULT
5–72
FIGURE 5–21: Ground instantaneous overcurrent scheme logic
PATH: SETPOINTS S4 ELEMENTS


] W1 RESTD GND FAULT
FUNCTION: Disabled
W1 RESTD GND FAULT
MESSAGE
RLYS (1-8): --------
W1 RESTD GND FAULT
MESSAGE
TARGET: Latched
W1 RESTD GND FAULT
MESSAGE
PICKUP: 0.08 x CT
W1 RESTD GND FAULT
MESSAGE
SLOPE: 10%
W1 RESTD GND FAULT
MESSAGE
DELAY: 0.10 s
W1 RESTD GND FAULT
MESSAGE
BLOCK: Disabled
Restricted ground fault protection is often applied to transformers having impedance
grounded wye. It is intended to provide sensitive ground fault detection for low magnitude
fault currents which would not be detected by the percent differential element.
FIGURE 5–22: Restricted earth ground fault protection
RESTRICTED GROUND

Range:
Range:
Range:
Range:
Range:
Range:
Range:
87T
Rg
87TG
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETPOINTS
W1(3) RESTD GND FAULT

Enabled, Disabled
1 to 8
Self-Reset, Latched, None
0.02 to 20.00 x CT in steps of
0.01
0 to 100% in steps of 1
0.00 to 600.00 s in steps of 0.01
Logc Inpt 1 to 16, Virt Inpt 1 to
16, Output Rly 2 to 8, SelfTest
Rly, Vir Outpt 1 to 5, Disabled