Protection Schemes
745
Transformer Management Relay
Commission
ing
http://www.GEindustrial.com/multilin
7–22
GE Multilin
e) Reset Time
A precise measurement of the reset time requires a relay test set capable of
dynamic operation, with three sequenced stages, each with programmable current
levels and time duration, and flexible external contact triggering. To perform such a
test, contact GE Multilin for detailed test instructions.
A simple verification of the reset mode selected by
S4 ELEMENTS
!"
NEUTRAL OC
!
W1
NTRL TIME OC
!"
W1 NEUTRAL TIME OC RESET
is obtained using the setup shown in
FIGURE 7–9: General Test Setup on page 7–18. The test consists of repetitive
operating time measurements in quick succession. If the reset is set for
“Instantaneous”, the operating time is always equal to the nominal time derived
from the selected curve. If the reset is set as “Linear”, the operating time varies as a
function of the time between successive applications of current. The variations in
operating time are easier to detect if this test is performed at current multiples of 2
to 3 times the pickup level.
f) Winding 2 or 3 Elements
Since 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. To test Winding 2 elements, disable all protection elements
except for
W2 NEUTRAL TIME OVERCURRENT
. Connect the current signal to X = H4 and
Y = G4 and repeat tests in this section. To test Winding 3 elements, disable all
protection elements except for
W3 NEUTRAL TIME OVERCURRENT
. Connect the current
signal to X = H7 and Y = G7 and repeat the tests in this section.
The blocking from logic input, if enabled, can be tested as described in
earlier tests for other elements.
Neutral Instantaneous
Overcurrent 1
a) Description
This procedure verifies that the Neutral Instantaneous Overcurrent performance is
as per the in-service settings. Settings for these elements are found under the
S4
ELEMENTS
!"
NEUTRAL OC
!"
W1 NTRL INST OC 1
setpoints menu. 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
.
b) 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 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 relays (and all the selected auxiliary relays) operate. Com-
pare the measured operating level against the
S4 ELEMENTS
!"
NEUTRAL OC
!"
W1 NTRL INST OC 1
!"
W1 NEUTRAL INST OC 1 PICKUP
value.
CURRENT
MULTIPLE
NOMINAL
TIME
MEASURED
TIME
1.5
3
5
NOTE
Summary of Contents for Multilin 745
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