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Section 10
Testing functionality by secondary injection
10.3.1.2
10.3.2
10.3.2.1
70
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.
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 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.
For more detailed formulas, please refer to the Application
manual.
Completing the test
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.
Restricted earth-fault protection, low impedance REFPDIF
Prepare the IED for verification of settings outlined in section
verify
settings".
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
1MRK 504 160-UEN -
"Preparing the IED to
Transformer protection RET650 2.1 IEC
Commissioning manual
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