Protection Schemes
745
Transformer Management Relay
Commission
ing
http://www.GEindustrial.com/multilin
7–20
GE Multilin
Phase Instantaneous
Overcurrent 1
a) Description
This procedure verifies that the Phase Instantaneous Overcurrent performance
matches the in-service settings. The settings for these elements are found under
the
S4 ELEMENTS
!"
PHASE OVERCURRENT
setpoints menu. The testing occurs at
current multiples of at least five times the rated CT secondary value.
Do not leave
the current signal on for more than a few seconds!
b) Winding 1 Elements
To ensure that only the Phase Instantaneous Overcurrent 1 element operates the
trip relays (and any other output relays) selected by the logic, disable all protection
features except Phase Instantaneous Overcurrent 1. Use the general test setup
shown in FIGURE 7–9: General Test Setup on page 7–18.
Connect the current supply to terminals X = H1 and Y = G1 to test the Winding 1
Phase A element. Monitor the appropriate output relays as per the relay FlexLogic™
settings.
c) Pickup Level
1. With the interval timer disabled, apply the current signal and increase its mag-
nitude until the trip relay (and all selected auxiliary relays) operate. Compare
the measured operating level against the
S4 ELEMENTS
!"
PHASE OC
!"
W1
PHASE INST OC 1
!"
W1 PHASE INST OC 1 PICKUP
setpoint.
2. Check that Trip, Pickup, and Phase A(C) LEDs turn on when the element
operates. Check that one of the following messages is displayed:
LATCHED a: W1 Phase Inst OC 1
or
OPERATED a: W1 Phase 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 Phase LEDs should
remain on if the
W1 PHASE INST OC 1 TARGET
was selected as “Latched”.
Otherwise, only the Trip LED should stay on.
4. Reset indicators and clear messages.
d) Operating Time
Using the setup shown in FIGURE 7–9: General Test Setup on page 7–18 and the
Interval Timer enabled, set the current level to 1.5 times the operating level of the
element. Apply current suddenly by closing the double-pole switch. Record the
operate time and compare it to the
S4 ELEMENTS
!"
PHASE OC
!"
W1 PHASE INST OC 1
!"
W1 PHASE INST OC 1 DELAY
setpoint value.
e) Phase B and C Elements
If the Phase A element performed correctly and met specifications, repeat the
Pickup Level portion of the above test for Phases B and C of Winding 1. For Phase B,
X = H2 and Y = G2. For Phase C, X = H3 and Y = G3. The displayed message
should change to indicate the correct phase, winding, and element that operated.
f) Winding 2 and 3 Elements
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 above for each winding.
Phase Instantaneous
Overcurrent 2
The Phase Instantaneous Overcurrent 2 elements are identical to the Phase
Instantaneous Overcurrent 1 elements. As such, the same test procedure can be
used to verify their correct operation. Disable all protection features except the
Phase Instantaneous Overcurrent 2 elements and follow the steps in the previous
section, making the appropriate changes for the display indications and output
relays which are operated by the Phase Instantaneous Overcurrent 2 elements.
The blocking from logic input, if enabled, can be tested as described in
earlier tests for other elements.
NOTE
Summary of Contents for Multilin 745
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