GE Power Management 745 Transformer Management Relay 10-29
10 COMMISSIONING 10.6 PROTECTION SCHEMES
10
To ensure only the Ground Instantaneous Overcurrent 1 element operates the trip relays (and any other output
relays) selected by the logic, disable all protection features except Ground Instantaneous Overcurrent 1. Use
the general test setup shown in Figure 10–9: GENERAL TEST SETUP on page 10–21.
Connect the current supply to terminals X = H10 and Y = G10 to test the Winding 1 element. Monitor the
appropriate output relays as per the relay FlexLogic settings.
b) PICKUP LEVEL
1. With the interval timer disabled, apply the current signal and increase its magnitude until the trip relay (and
all the selected auxiliary relays) operate. Compare the measured operating level against the setpoint:
SETPOINTS/S4 ELEMENTS/GROUND OC/W1 GND INST OC 1/W1 GND INST OC 1 PICKUP
2. When the element operates, check that the TRIP and MESSAGE indicators are flashing and the following
message is displayed:
3. Reduce the current until the element resets. The reset level should be 97% of the operate level. When the
element resets the TRIP, GROUND and message indicators should remain on if the TARGET was selected
as latched. Otherwise, only the TRIP indicator should stay on.
4. Reset indicators and clear messages.
c) OPERATING TIME
Using the setup shown in Figure 10–9: GENERAL TEST SETUP on page 10–21 with the Interval Timer
enabled, set the current level to 1.5 times the element operate level and apply suddenly by closing the double-
pole switch. Record the operate time and compare to the setting value in:
SETPOINTS/S4 ELEMENTS/GROUND OC/W1 GND INST OC 1/W1 GND INST OC 1 DELAY
d) WINDING 2 OR ELEMENT
Only two Ground Instantaneous Overcurrent 1 elements can be in service simultaneously.
Because the Winding 2 and 3 elements can be set with completely different parameters than the Winding 1
elements, it is necessary to repeat the full set of tests described in this section for each winding.
The blocking from logic input, if enabled, can be tested as described in earlier tests for other
elements.
10.6.12 GROUND INSTANTANEOUS OVERCURRENT 2
The Ground Instantaneous Overcurrent 2 elements are identical to the Ground Instantaneous Overcurrent 1
elements. Consequently, the same test procedure may be used to verify their correct operation. Disable all pro-
tection features except Ground Instantaneous Overcurrent 2. Make the appropriate changes for the display
indications and output relays operated by the Ground Instantaneous Overcurrent 2 elements.
yy LATCHED (OPERATED):
yy W1 Gnd Inst OC 1
NOTE
NOTE
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