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1MRK 504 165-UEN Rev. K
transformer inputs as the transformer differential protection. Make sure that the transformer
differential functions T2WPDIF or T3WPDIF are unblocked.
2.
Connect the test set for injection of three-phase currents to the current terminals of the IED,
which are connected to the CTs on the HV side of the power transformer.
3.
Increase the current in phase L1 until the protection function operates and note the operating
current.
4.
Check that the trip and alarm contacts operate according to the configuration logic.
5.
Decrease the current slowly from operate value and note the reset value.
Depending on the power transformer vector group (Yd and so on), the single-phase injection
current may appear as differential current in one or two phases and the operating value of the
injected single-phase current will be different.
6.
Check in the same way the function by injecting current in phases L2 and L3 respectively.
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 measuring circuits connected to the CTs on the LV side and other
current inputs to the transformer differential protection.
11.
Finally check that trip information is stored in the event menu.
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 frequency in phase L1. Increase the
current in phase L1 above the start value measured in step 6. Repeat test with current injection
in phases L2 and L3 respectively.
The balancing of currents flowing into and out of the differential zone is checked by primary
injection testing.
Fifth harmonic blocking can be tested in a similar way.
11.3.1.2
Completing the test
Continue to test another function or end the test by changing the TESTMODE setting to Off. Restore
connections and settings to the original values, if changed for testing purposes.
11.3.2
High impedance differential protection HZPDIF
Prepare the IED for verification of settings as outlined in section
section
11.3.2.1
Verifying the settings
1.
Connect a single-phase or three-phase test set to inject the operating voltage. The injection is
done across the measuring branch.
Transformer protection RET670
Commissioning manual
Information on how to use the event menu is found in the operator's manual.
For more detailed formulas, please refer to the Application manual.
"Preparing for test"
in this chapter.
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Testing functionality by secondary injection
"Requirements"
and
Section 11
SEMOD54284-86 v5
SEMOD55257-42 v3
SEMOD55257-46 v5
93
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