GE Multilin
745 Transformer Management Relay
8-23
8 COMMISSIONING
8.5 PROTECTION SCHEMES
8
trip contact closes. The operate level should correspond to the
S4 ELEMENTS
ÖØ
GROUND OC
Ö
W1 GND TIME OC
ÖØ
W1 GROUND TIME OC PICKUP
setpoint.
3.
When the element operates, check that the Trip, Ground, and Pickup LEDs are on and one of the following messages
is displayed:
4.
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 LEDs should remain on if the
W1 GROUND TIME OC TARGET
was selected as "Latched".
Otherwise, only the Trip LED should remain on.
5.
Reset indicators and clear messages.
OPERATING TIME:
Using a table like the one shown blow, 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 Figure 8–9: General Test
Setup on page 8–18 with the Interval Timer enabled, set the current level to the desired value and apply suddenly by clos-
ing the double-pole switch. Record the operate time and compare to the expected value. Repeat for the all the 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 with the
S4 ELEMENTS
ÖØ
GROUND OC
Ö
W1 GND TIME OC
ÖØ
W1 GROUND
TIME OC RESET
setpoint is obtained using the setup in Figure 8–9: General Test Setup on page 8–18. The procedure con-
sists of repetitive operating time measurements in quick succession. If the reset is selected for “Instantaneous”, the operat-
ing time always equals the nominal time derived from the selected curve. If the reset is selected as “Linear”, the operating
time varies as a function of the time between successive applications of the current signal. If this test is performed at cur-
rent multiples of 2 to 3 times the pickup level, the variations in operating time are easier to detect.
WINDING 2 OR 3 ELEMENTS:
Because the second Ground Time Overcurrent element could be set with completely different parameters than the element
for the first winding, it is necessary to repeat the full set of tests described above for each winding.
To test the second element, disable all protection elements except for the
W2 GROUND TIME OVERCURRENT
(or
W3 GROUND
TIME OVERCURRENT
) element. Connect the current signal to X = F12 and Y = E12. Repeat all the tests described for the
Winding 1 Ground Time Overcurrent element in this section.
The blocking from logic input, if enabled, can be tested as described in earlier tests for other elements.
LATCHED
W1 Gnd Time OC
OPERATED
W1 Gnd Time OC
CURRENT
MULTIPLE
NOMINAL TIME
MEASURED
TIME
1.5
3
5
NOTE
Содержание TRANSFORMER MANAGEMENT RELAY 745
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