This version of the export limit test procedure is intended for stand-alone reverse power and underpower relay packages provided to meet the requirements of an export-limited distributed generation facility. It should be understood that in the reverse power application, the relay will provide a trip output with power in the export direction (toward the EDTI distribution system).
Step 1: Power flow test at minimum, midpoint and maximum pickup level settings
Determine the appropriate secondary pickup current for the desired export power flow of 0.5 secondary watts (the agreed-upon minimum pickup setting; assumes 5 amp and 120 V CT/PT secondary). Apply nominal voltage with minimum current setting at zero degrees in the trip direction. Increase the current to pickup level. Observe the relay trip's (LCD or computer display) indication of power values. Note the indicated power level at which the relay trips. The power indication should be within 2% of the expected power. For relays with adjustable settings, repeat this test at the midpoint and maximum settings. Repeat at phase angles of 90, 180 and 270 degrees and verify that the relay does not operate (measured watts will be zero or negative).
Step 2: Leading power factor test
Apply rated voltage to the relay with a minimum pickup current setting (calculated value for system application) and apply a leading power factor load current in the non-trip direction (current lagging voltage by 135 degrees). Increase the current to the relay rated current and verify that the relay does not operate. For relays with adjustable settings, this test should be repeated at the minimum, midpoint and maximum settings.
Step 3: Minimum power factor test
At nominal voltage and with the minimum pickup (or ranges) determined in Step 1, adjust the current phase angle to 84 or 276 degrees. Increase the current level to pickup (about 10 times higher than at 0 degrees) and verify that the relay operates. Repeat for phase angles of 90, 180 and 270 degrees and verify that the relay does not operate.
Step 4: Negative-sequence voltage test
Using the pickup settings determined in Step 1, apply rated relay voltage and current at 180 degrees from tripping direction, to simulate normal load conditions (for three-phase relays, use Ia at 180, Ib at 60 and Ic at 300 degrees). Remove phase-one voltage and observe that the relay does not operate. Repeat for phases two and three.
Step 5: Load current test
Using the pickup settings determined in Step 1, apply rated voltage and current at 180 degrees from the tripping direction, to simulate normal load conditions (use Ia at 180, Ib at 300 and Ic at 60 degrees). Observe that the relay does not operate.
Step 6: Unbalanced fault test
Using the pickup settings determined in Step 1, apply rated voltage and 2 times rated current, to simulate an unbalanced fault in the non-trip direction (use Va at 0 degrees, Vb and Vc at 180 degrees, Ia at 180 degrees, Ib at 0 degrees and Ic at 180 degrees). Observe that the relay, especially single-phase, does not operate.
Step 7: Time-delay settings test
Apply Step 1 settings and set the time delay to the minimum setting. Adjust the current source to the appropriate level to determine operating time, and compare against calculated values. Verify that the timer stops when the relay trips. Repeat at midpoint and maximum delay settings.
Step 8: Dielectric test
Perform the test described in IEC 414 using 2 kV RMS for 1 minute.
Step 9: Surge withstand
Perform the surge withstand test described in IEEE C37.90.1.