GE 745 - 5.6.7.2 Ground Time Overcurrent

5–70 745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
S4 ELEMENTS CHAPTER 5: SETPOINTS
5.6.7.2 Ground Time Overcurrent
PATH: SETPOINTS  S4 ELEMENTS  GROUND OC  W1(3) GND TIME OC
• W1(3) GROUND TIME OC PICKUP: Enter the level of ground current (in units of relay
nominal current) above which the winding 1(3) ground time overcurrent element will
pickup and start timing.
• W1(3) GROUND TIME OC SHAPE: Select the time overcurrent curve shape to be used
for the winding 1(3) ground time overcurrent element. Refer to Time Overcurrent
Curves on page 5–59 for a description of the time overcurrent curve shapes.
• W1(3) GROUND TIME OC MULTIPLIER: Enter the multiplier constant by which the
selected time overcurrent curve shape (the base curve) is to be shifted in time.
• W1(3) GROUND TIME OC RESET: Select the “Linear” reset to coordinate with
electromechanical time overcurrent relays, in which the reset characteristic (when the
current falls below the reset threshold before tripping) is proportional to ratio of
“energy” accumulated to that required to trip. Select the “Instantaneous” reset to
coordinate with relays, such as most static units, with instantaneous reset
characteristics.
 W1 GND []
TIME OC
W1 GROUND TIME OC
FUNCTION: Enabled
Range: Enabled, Disabled
MESSAGE
W1 GROUND TIME OC
RLYS (1-8): --------
Range: 1 to 8
MESSAGE
W1 GROUND TIME OC
TARGET: Latched
Range: Self-Reset, Latched, None
MESSAGE
W1 GROUND TIME OC
PICKUP: 0.85 x CT
Range: 0.05 to 20.00 x CT in steps of
0.01
MESSAGE
W1 GROUND TIME OC
SHAPE: Ext Inverse
Range: see description below
MESSAGE
W1 GROUND TIME OC
MULTIPLIER: 1.00
Range: 0.00 to 100.00 in steps of 0.01
MESSAGE
W1 GROUND TIME OC
RESET: Linear
Range: Instantaneous, Linear
MESSAGE
W1 GROUND TIME OC
BLOCK: Disabled
Range: Logc Inpt 1 to 16, Virt Inpt 1 to
16, Output Rly 2 to 8, SelfTest
Rly, Vir Outpt 1 to 5, Disabled