6.
Check in the same way the function by injecting current in phases L2 and L3.
7.
Inject a symmetrical three-phase current and note the operate value.
8.
Connect the timer and set the current to twice the operate value.
9.
Switch on the current and note the operate time.
10. Check in the same way the functioning of the measuring circuits connected to the CTs on
the neutral point side of the generator.
11.
Finally check that trip information is stored in the event menu.
Information on how to use the event menu is found in the operator’s
manual.
12.
If available on the test set a second-harmonic current of about 20% (assumes 15%
setting on I1/I2 ratio parameter) can be added to the fundamental tone in phase L1.
Increase the current in phase L1 above the start value measured in step
. Repeat test
with current injection in phases L2 and L3 respectively.
Fifth-harmonic blocking can be tested in a similar way.
The balancing of currents flowing into and out of the differential zone is typically checked
by primary testing.
12.3.3.2
Completing the test
SEMOD155702-82 v3
Continue to test another function or end the test by changing the
TestMode setting to Off.
Restore connections and settings to their original values, if they were changed for testing
purposes.
12.3.4
Restricted earth-fault protection, low impedance REFPDIF
SEMOD55252-82 v7
Prepare the IED for verification of settings as outlined in section
in this chapter.
12.3.4.1
Verifying the settings
SEMOD55252-86 v10
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.
11.
Inject a current in the neutral-to-earth circuit with the same phase angle and with polarity
corresponding to an external fault.
12.
Increase the current to five times the operating value and check that the protection does
not operate.
13. Finally check that trip information is stored in the event and disturbance recorder.
1MRK 502 067-UEN B
Section 12
Testing functionality by secondary injection
101
Commissioning manual
