7–34 745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
PROTECTION SCHEMES CHAPTER 7: COMMISSIONING
Enter the expected operating times from the timing curve applied in the
settings.
Using FIGURE 7–9: General test setup on page 7–25 with 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 the all the desired values of current.
7.5.10.5 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 GEGE
Multilin for detailed test instructions.
A simple verification of the reset mode selected with the
S4 ELEMENTS GROUND OC
W1 GND TIME OC
W1 GROUND TIME OC RESET setpoint is obtained using the setup in
FIGURE 7–9: Ge n e r a l t e s t s e t u p on page 7–25. The procedure consists of repetitive
operating time measurements in quick succession. If the reset is selected for
“Instantaneous”, the operating 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
current multiples of 2 to 3 times the pickup level, the variations in operating time are easier
to detect.
7.5.10.6 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.
Note
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
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