The operate value in secondary volts is calculated according
to the following equations:
For phase-to-earth measurement:
U UBase VT
VTprim
1
100
3
<
× ×
sec
IECEQUATION2430 V1 EN-US (Equation 97)
For phase-to-phase measurement:
U
UBase
VT
VTprim
1
100
<
× ×
sec
IECEQUATION2431 V1 EN-US (Equation 98)
5. Increase the measured voltage to rated load conditions.
6. Check that the
START signal resets.
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 ×
U1<.
For example, if the inverse time curve A is selected, the trip
signals TR1 and TRIP operate after a time corresponding to
the equation:
IECEQUATION2428 V1 EN-US (Equation 99)
where:
t(s) Operate time in seconds
k1 Settable time multiplier of the function for step 1
U Measured voltage
U1< Set start voltage for step 1
For example, if the measured voltage jumps from the rated value to 0.8 times
the set start voltage level and time multiplier k1 is set to 0.05 s (default
value), then the TR1 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
dif
ferent voltage levels.
11. Repeat the above described steps for Step 2 of the function.
1MRK 505 378-UEN A Section 11
Testing functionality by secondary injection
Line differential protection RED670 2.2 IEC 197
Commissioning manual
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