Ground Instantaneous Overcurrent - GE TRANSFORMER MANAGEMENT RELAY 745 Instruction Manual

8.5 PROTECTION SCHEMES
a) GROUND IOC 1
This procedure verifies that the Ground Instantaneous Overcurrent performance matches the in-service settings. Settings
for these elements are found under the
settings require you to test at current multiples of several times the rated CT secondary value do not leave the current sig-
nal on for more than a few seconds.
WINDING 1 ELEMENT:
To ensure only the Ground IOC 1 element operates the trip relays (and any other output relays) selected by the logic, dis-
able all protection features except Ground IOC 1. Use the general test setup shown in Figure 8–9: General Test Setup on
page 8–18.
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.
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
W1 GND INST OC 1
2. When the element operates, check that the Trip and Message LEDs are flashing and one of the following messages is
displayed:
LATCHED
W1 Gnd Inst OC 1
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 LEDs should remain on if the
"Latched". Otherwise, only the Trip LED should stay on.
4. Reset indicators and clear messages.
OPERATING TIME:
Using the setup shown in Figure 8–9: General Test Setup on page 8–18 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
S4 ELEMENTS
WINDING 2 OR 3 ELEMENT:
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.
Only two Ground Instantaneous Overcurrent 1 elements can be in service simultaneously.
NOTE
The blocking from logic input, if enabled, can be tested as described in earlier tests for other elements.
8
NOTE
b) GROUND IOC 2
The Ground IOC 2 elements are identical to the Ground IOC 1 elements. Consequently, the same test procedure may be
used to verify their correct operation. Disable all protection features except Ground IOC 2. Make the appropriate changes
for the display indications and output relays operated by the Ground IOC 2 elements.
8-24
Courtesy of NationalSwitchgear.com
S4 ELEMENTS GROUND OC
setpoint.
W1 GND INST OC 1 PICKUP
OPERATED
W1 Gnd Inst OC 1
GROUND OC W1 GND INST OC 1
745 Transformer Management Relay

8.5.9 GROUND INSTANTANEOUS OVERCURRENT

setpoints menu. If your relay
W1 GND INST OC 1
S4 ELEMENTS
W1 GND INST OC 1 TARGET
W1 GND INST OC 1 DELAY
8 COMMISSIONING
GROUND OC
was selected as
setting value.
GE Multilin