GE Multilin
745 Transformer Management Relay
8-21
8 COMMISSIONING
8.5 PROTECTION SCHEMES
8
OPERATING TIME:
Using a table like the one shown below, select three (3) or four (4) values of current multiples at which timing is to be mea-
sured. Enter the expected operating times from the timing curve applied in the settings. Using the setup in Figure 8–9: Gen-
eral Test Setup on page 8–18 and the Interval Timer enabled, set the current level to the desired value and apply suddenly
by closing the double-pole switch. Record the operate time and compare to the expected value. Repeat for all desired val-
ues of current.
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
ÖØ
NEUTRAL OC
Ö
W1 NTRL TIME OC
ÖØ
W1 NEUTRAL TIME
OC RESET
is obtained using the setup shown in Figure 8–9: General Test Setup on page 8–18. 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 per-
formed at current multiples of 2 to 3 times the pickup level.
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 nec-
essary 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
. Con-
nect 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.
8.5.7 NEUTRAL INSTANTANEOUS OVERCURRENT
a) NEUTRAL IOC 1
This procedure verifies that the Neutral IOC performance is as per the in-service settings. Settings for these elements are
found under the
S4 ELEMENTS
ÖØ
NEUTRAL OC
ÖØ
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 sec-
onds
.
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 8–9: General Test Setup on page 8–18.
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.
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
S4 ELEMENTS
ÖØ
NEUTRAL OC
ÖØ
W1 NTRL INST OC 1
ÖØ
W1 NEUTRAL INST OC 1 PICKUP
value.
CURRENT
MULTIPLE
NOMINAL TIME
MEASURED
TIME
1.5
3
5
NOTE
Содержание TRANSFORMER MANAGEMENT RELAY 745
Страница 2: ...Courtesy of NationalSwitchgear com ...