inputs as the generator differential protection, are set off. Make sure that thegenerator differential function is unblocked.2. Connect the test set for injection of three-phase current to the current IEDs,which are connected to the CTs on the HV side of the generator.3. Increase the current in phase L1 until the protection function operates andnote the operating current.4. Check that trip and alarm contacts operate according to the configurationlogic.5. Decrease the current slowly from operate value and note the reset value.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 tothe 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 theoperator’s manual.12. If available on the test set a second-harmonic current of about 20% (assumes15% setting on I1/I2 ratio parameter) can be added to the fundamental tone inphase L1. Increase the current in phase L1 above the start value measured instep 3. 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 istypically checked by primary testing.13.3.3.2 Completing the test SEMOD155702-82 v3Continue to test another function or end the test by changing the TESTMODEsetting to Off. Restore connections and settings to their original values, if they werechanged for testing purposes.13.3.4 Restricted earth fault protection, low impedance REFPDIFSEMOD55252-82 v8Prepare the IED for verification of settings outlined in Section "Preparing the IEDto verify settings".13.3.4.1 Verifying the settings SEMOD55252-86 v11Section 13 1MRK 502 073-UEN ATesting functionality by secondary injection134 Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062Commissioning manual
