ABB RET670 - Page 217

If tDef_OC is set to a value different from 0 s, then this time delay is
added to the one that is defined by the IDMT characteristic.
10. Check the pickup and trip information that are stored in the event menu.
11. The previous step 8 or 9 may be repeated also for the first and second section of the
characteristic.
12. Supply the IED with symmetric three-phase voltages at their rated values. Go to
Main menu/Settings/IED Settings/Current protection/
VoltageRestOverCurr(51V,2(I>/V<))/VRPVOC(51V,2(I>/V<)):1/
Undervoltage and set the setting Operation_UV = Enabled to activate the
undervoltage stage.
13. Slowly decrease the voltage in two phases simultaneously, until the STUV and
PICKUP signals appear.
14. Note the trip value. The set trip value in secondary volts is calculated according to
the following equation:
Pickup Volt VBase VT
VTprim
_ sec
100
3
× ×
ANSIEQUATION2436 V2 EN (Equation 95)
If the VRPVOC function is used as an overcurrent protection with
undervoltage seal-in, it is necessary to first inject sufficient current
to activate the STOC signal before the under-voltage step is allowed
to trip. In order to achieve that, apply symmetric three-phase
voltages at their rated value and then inject a current IA that is 200%
higher than the set tripping level. Then slowly decrease the voltage
in two phases simultaneously, until the STUV and PICKUP signals
appear.
15. Increase slowly the applied voltages of the previous two phases and note the reset
value.
16. Check that the trip output of the relay is connected to the input channel of the test in
order to stop the injection and measure the trip time.
17. Inject symmetric three-phase voltages at their rated value and check that the STUV
and PICKUP signals reset as well as the trip signals of the function block (TRIP and
TRUV).
18. Instantaneously decrease the voltage in two phases simultaneously to a value 20%
lower than the set trip value (take into account the previous note if VRPVOC is
configured in ACT with the undervoltage seal-in feature).
19. Measure the definite time delay for the TRUV and TRIP signals and compare it with
the set value tDef_UV.
20. Check that pickup and trip information is stored in the event menu.
1MRK 504 165-UUS - Section 11
Testing functionality by secondary injection
Transformer protection RET670 2.2 ANSI 211
Commissioning manual