Protection Schemes
745
Transformer Management Relay
Commissioning
http://www.GEindustrial.com/multilin
7–19
GE Multilin
the pickup level. Once the relay drops out, slowly increase the current until the
trip contact closes. The operate level should correspond to the pickup setting.
2. Check that one of the following messages is displayed:
LATCHED a: W1 Phase Time OC or OPERATED a: W1 Phase Time OC
The message will indicate
LATCHED or OPERATED, depending on the setting for
the target.
d) Operating Time
Using a table like the one shown below, select three (3) or four (4) values of current
multiples at which the timing is to be measured. Enter the expected operating times
from the timing curve applied in the settings. 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 the desired value and apply suddenly by closing the double-pole switch.
Record the operating time and compare it to the expected value. Repeat for all
desired values of current.
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 external contact, and flexible triggering. To perform such a
test, please contact GE Multilin for detailed test instructions.
A simple verification the selected reset mode can be obtained using FIGURE 7–9:
General Test Setup on page 7–18. The procedure consists of performing repetitive
operating time measurements in quick succession. If the reset is selected for
instantaneous, the operating time will always be equal to the nominal time derived
from the selected curve. If the reset is selected as linear, the operating time will
vary as a function of the time between successive application of the current signal.
If performed at current multiples of 2 to 3 times the pickup level, the variations in
operating time will be easier to detect.
f) 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 the B and C phases 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.
g) Winding 2 and 3 Elements
Because the Winding 2 and 3 elements can be set with completely different
parameters than the elements for Winding 1, it is necessary to repeat the full set of
tests described above for each winding.
The blocking from logic input, if enabled, can be tested as described in
earlier tests for other elements.
CURRENT
MULTIPLE
NOMINAL
TIME
MEASURED
TIME
1.5
3
5
NOTE
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