10-30
745 Transformer Management Relay
GE Power Management
10.6 PROTECTION SCHEMES
10 COMMISSIONING
10
10.6.13 RESTRICTED GROUND FAULT
This procedure verifies that the Restricted Ground Fault performance matches the in-service settings. The
ground element measures the current signal connected to the ground current input CT, H10 and G10 or F12
and E12. The neutral (3
I
o
) current is calculated from the vector sum of the three phase currents. Injecting cur-
rent into one phase automatically produces a neutral current (i.e. 3
I
o
=
I
A
). Settings for these elements are
found under:
SETPOINTS/S4 ELEMENTS/RESTRICTED GROUND/W1 RESTD GND FAULT/...
a) WINDING #1 ELEMENT
To ensure that only the Restricted Ground Fault element operates the trip relays (and any other output relays
selected by the logic) disable all protection features except Restricted Ground Fault.
Using a current supply as shown in the figure below, connect the
I
1
current source to terminals H1 and G1 for
the Winding 1 phase current element and
I
2
to terminals G10 and H10 as shown for the ground current ele-
ment. Monitor the appropriate output relays as per the relay FlexLogic settings.
Figure 10–10: RESTRICTED GROUND TEST SETUP
b) PICKUP LEVEL
1.
With the interval timer disabled, apply the current signal feeding the phase current element and increase
its magnitude slowly until the trip relay, and all the selected auxiliary relays, operate. The operate level
should correspond to the pickup setting in:
SETPOINTS/S4 ELEMENTS/RESTRICTED GROUND/W1 RESTD GND FAULT/W1 RESTD GND FAULT PICKUP
2.
When the element operates, check that the TRIP, GROUND and PICKUP LEDs are on 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 and message indicators should remain on if the TARGET was selected as
latched. Otherwise, only the TRIP indicator should remain on.
4.
Reset indicators and clear messages.
yy
LATCHED (OPERATE):
yy
W1 Restd Gnd Fault
Summary of Contents for 745 TRANSFORMER MANAGEMENT RELAY
Page 30: ...2 8 745 Transformer Management Relay GE Power Management 2 3 SECURITY 2 GETTING STARTED 2 ...
Page 210: ...7 36 745 Transformer Management Relay GE Power Management 7 2 BLOCK DIAGRAMS 7 SCHEME LOGIC 7 ...
Page 322: ...9 12 745 Transformer Management Relay GE Power Management 9 3 USING 745PC 9 745 PC SOFTWARE 9 ...
Page 396: ...A 4 745 Transformer Management Relay GE Power Management A 1 FIGURES AND TABLES APPENDIXA A ...
Page 400: ...C 2 745 Transformer Management Relay GE Power Management C 1 WARRANTY INFORMATION APPENDIXC C ...
Page 406: ...vi 745 Transformer Management Relay GE Power Management ...
Page 407: ...GE Power Management 745 Transformer Management Relay NOTES ...
