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Current protection Chapter 11
Verifying settings by secondary
injection
6 Current protection
6.1 Instantaneous phase overcurrent protection (PIOC, 50)
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 IED does not exceed four times its rated val-
ue.
6.1.1 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. Set operation mode to 1 out of 3.
3. Increase the injected current in the Ln phase until the TRL (n=1–3)
signal appears.
4. Switch the fault current off.
Observe the maximum permitted overloading of the current circuits in the
IED
5. Compare the measured operating current with the set value.
6. Set operation mode to 2 out of 3 and inject current into one of the
phases. Check- no operation.
6.1.2 Completing the test
Continue to test another function or end the test by changing the test mode setting to OFF.
6.2 Four step phase overcurrent protection (POCM, 51/67)
Prepare the IED for verification of settings outlined in section 3 "Overview"and section 2 "Pre-
paring for test" in this chapter.
Directional phase overcurrent current function
Procedure
1. Connect the test set for appropriate current injection to the appropri-
ate IED terminals.
If 1 of 3 currents for operation is chosen: Connect the injection current to
terminals L1 and neutral.
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