Table of Contents
Advertisement
10.6 PROTECTION SCHEMES
This procedure verifies that the Neutral Instantaneous Overcurrent performance is as per the in-service set-
tings. Settings for these elements are found under:
SETPOINTS/S4 ELEMENTS/NEUTRAL OC/W1 NTRL INST OC 1/
If the relay settings require testing at current multiples of several times the rated CT secondary value, do not
leave the current signal on for more than a few seconds .
a) WINDING #1 ELEMENT
To ensure that only the Neutral Instantaneous Overcurrent 1 element operates the trip relays (and any other
output relays) selected by the logic, disable all protection features except Neutral 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 = H1 and Y = G1 to test the Winding 1 A-phase 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 relays
(and all the selected auxiliary relays) operate. Compare the measured operating level against the value in:
SETPOINTS/S4 ELEMENTS/NEUTRAL OC/W1 NTRL INST OC 1/W1 NEUTRAL INST OC 1 PICKUP
2. Check that, when the element operates, the TRIP and PICKUP indicators are on and the following mes-
sage is displayed:
SS LATCHED (OPERATED)
SS W1 Ntrl 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 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
With the setup shown in Figure 10–9: GENERAL TEST SETUP on page 10–21 and the Interval Timer enabled,
set the current level to 1.5 times the operate level of the element and apply suddenly by closing the double-
pole switch. Record the operate time and compare to the value in:
SETPOINTS/S4 ELEMENTS/NEUTRAL OC/W1 NTRL INST OC 1/W1 NEUTRAL INST OC 1 DELAY
d) WINDING 2 AND 3 ELEMENTS
Only two Neutral Instantaneous Overcurrent 1 elements can be in service simultaneously.
NOTE
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.
NOTE
10
10-26
10.6.8 NEUTRAL INSTANTANEOUS OVERCURRENT 1
745 Transformer Management Relay
10 COMMISSIONING
GE Power Management
Advertisement
Table of Contents
