1. Check that the IED settings are appropriate, especially the PICKUP value, the definite time delay
and the 1 out of 3 operation mode.
2. Supply the IED with three-phase voltages at their rated values.
3. Slowly decrease the voltage in one of the phases, until the PICKUP signal appears.
4. Note the trip value and compare it with the set value.
The trip value in secondary volts is calculated according to the following equations:
For phase-to-ground measurement:
sec
100
3
Vpickup VBase VT
VTprim
<
´ ´
ANSIEQUATION2430 V1 EN-US (Equation 100)
For phase-to-phase measurement:
sec
100
Vpickup VT
VBase
VTprim
<
´ ´
ANSIEQUATION2431 V1 EN-US (Equation 101)
5. Increase the measured voltage to rated load conditions.
6. Check that the PICKUP signal resets.
7. Instantaneously decrease the voltage in one phase to a value about 20% lower than the measured
trip 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 trip after a time corresponding to the equation:
( )
1
1
TD
t s
V
Vpickup
=
æ ö
-
ç ÷
<
è ø
ANSIEQUATION2428 V1 EN-US (Equation 102)
where:
t(s) Trip 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 trip 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 of the function.
Extended testing
M13796-35 v8
The tests above can be repeated for 2 out of 3 and for 3 out of 3 operation mode.
1MRK 504 165-UUS Rev. J Section 11
Testing functionality by secondary injection
Transformer protection RET670 205
Commissioning manual
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