Note that during this test setting SOTFMode must be set to Off.
The balancing of currents flowing into and out of the differential zone is
typically checked by primary testing when suitable supply facilities exist on site.
Fifth harmonic blocking can be tested in a similar way. Note, the blocking level
for the fifth harmonic is 10% higher than the I5/I1 Ratio setting.
6.3.1.2 Completing the test
Continue to test another function or end the testing by setting the parameter TestMode
to Off 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/Differential/T3WPDIF(87T,Id)/T3WPDIF: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.
6.3.2 Restricted earth-fault protection, low impedance REFPDIF
Prepare the IED for verification of settings as outlined in
5.1 "Preparing the IED to
verify settings".
Values of the logical signals for REFPDIF are available on the local HMI under Main
menu/Tests/Function status/Differential/REFPDIF(87,INd)/REFPDIF:X. The
Signal Monitoring in PCM600 shows the same signals that are available on the local
HMI.
6.3.2.1 Verifying the settings
1. Connect the test set for single-phase current injection to the protection terminals
connected to the CT in the power transformer neutral-to-earth circuit.
2. Increase the injection current and note the operating value of the protection
function.
3. Check that all trip and start contacts operate according to the configuration logic.
4. Decrease the current slowly from operate value and note the reset value.
5. Connect the timer and set the current to ten times the value of the IDMin setting.
6. Switch on the current and note the operate time.
7. Connect the test set to terminal L1 and neutral of the three-phase current input
configured to REFPDIF. Also inject a current higher than half the Idmin setting
in the neutral-to-earth circuit with the same phase angle and with polarity
corresponding to an internal fault.
8. Increase the current injected in L1, and note the operate value. Decrease the
current slowly and note the reset value.
9. Inject current into terminals L2 and L3 in the same way as in step 7 above and
note the operate and reset values.
10. Inject a current equal to 10% of rated current into terminal L1.
1MRK 502 049-UEN A Section 6
Testing functionality
45
Commissioning manual
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