7. Instantaneously decrease the voltage in one phase to a value about 20% lower than
the measured operate value.
8. Measure the time delay for the TRIP signal, and compare it with the set value.
9. Check the inverse time delay by injecting a voltage corresponding to 0.8 ×
Vpickup<.
For example, if the inverse time curve A is selected, the trip signals
TRST1 and TRIP operate after a time corresponding to the equation:
( )
1
1
TD
t s
V
Vpickup
=
æ ö
-
ç ÷
<
è ø
ANSIEQUATION2428 V1 EN (Equation 15)
where:
t(s) Operate time in seconds
TD1 Settable time multiplier of the function for step 1
V Measured voltage
Vpickup< Set pickup voltage for step 1
For example, if the measured voltage jumps from the rated value to 0.8 times the set
pickup voltage level and time multiplier TD1 is set to 0.05 s (default value), then the
TRST1 and TRIP signals operate at a time equal to 0.250 s ± tolerance.
10. The test above can be repeated to check the inverse time characteristic at different
voltage levels.
11. Repeat the above-described steps for step
2.
Extended testing
1. The tests above can be repeated for 2 out of 3 and for 3 out of 3 operation mode.
6.4.1.2 Completing the test
Continue to test another function or end the testing by setting the parameter TestMode to
Disabled under Main menu/Tests/IED test mode/TESTMODE:1. If another function is
tested, then set the parameter Blocked to No under Main menu/Tests/Function test
modes/Voltage/UV2PTUV(27,2U<)/UV2PTUV:1 for the function, or for each
individual function in a chain, to be tested next. Remember to set the parameter Blocked to
Yes, for each individual function that has been tested.
Section 6 1MRK 505 293-UUS A
Testing functionality
76
Commissioning manual
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