105
Current protection Chapter 11
Verifying settings by secondary
injection
12. Reverse the direction of the injected current and check that the pro-
tection does not operate.
13. If 2 of 3 or 3 of 3 currents for operation is chosen: Check that the
function will not operate with current in one phase only.
14. Repeat the above-described tests for the higher set stages.
15. Finally check that start and trip information is stored in the event
menu.
6.3 Instantaneous residual overcurrent protection (PIOC, 50N)
Prepare the IED for verification of settings as outlined in section 1 "Overview" and section 2
"Preparing for test" in this chapter.
To verify the settings the following fault type should be tested:
• One for a phase-to-earth fault
Ensure that the maximum continuous current of the terminal does not exceed four times its rated
value.
6.3.1 Measuring the operate limit of set values
Procedure
1. Inject a phase current into the IED with an initial value below that of
the setting.
2. Increase the injected current in the Ln or in the neutral (summated
current input) phase until the TRIP signal appears.
3. Switch the fault current off.
Observe the maximum permitted overloading of the current circuits in the
IED
4. Compare the measured operating current with the set value.
6.3.2 Completing the test
Continue to test another function or end the test by changing the test mode setting to OFF.
6.4 Four step residual overcurrent protection (PEFM, 51N/67N)
Prepare the IED for verification of settings as outlined in section 1 "Overview" and section 2
"Preparing for test" in this chapter.
Note!
Check of the non-directional phase over-current function. This is done in principle as instructed
above, without applying any polarizing voltage.
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