Entergy, Docket No. RC13-9, May 30, 2013
Reliability Standard: PRC-023-1
Requirement: 1
Region: SERC
Issue: Entergy, as a TO, self-reported an issue with PRC-023-1 R1 to SERC when it found that a transformer overcurrent relay was set below 150% of the transformer’s maximum nameplate rating. During a subsequent review of all transformer relay setpoints, Entergy found only 1 relay that would operate at 149.66% of the highest transformer rating, which is 0.34% below the required setpoint of 150%.
Finding: SERC determined that the issue posed a minimal risk to the reliability of the BPS because the historical loading of the transformer has not exceeded 62% of the nameplate rating and there was an opportunity for operator action because the relay would not have operated at loads up to 149.65% of the transformer’s Loadability Rating. Furthermore, loading scenarios exceeding 149.65% for more than 3 continuous hours would likely also have exceeded 150% capacity. This means that the relay would likely have actuated even if the setpoint had been correct. Lastly, the operators would have had 6.1 minutes to respond if loading had stopped at 150%.
Find, Fix and Track Entity, FERC Docket No. RC12-6 (December 30, 2011)
Reliability Standard: PRC-023-1
Requirement: R1
Region: FRCC
Issue: One (of 59) of FFT Entity’s transmission line relays was incorrectly set below the 150% requirement (25.536 ohms, 148.2%) and greater than the maximum allowed setting. The maximum primary ohm value the relay could have been set to is 25.083 ohms. Consequently, FFT Entity was unable to show through documentation or interviews with subject matter experts that the relay was set as required by the Standard.
Finding: FRCC determined the issue posed a minimal and not serious or substantial risk to the reliability of the BPS since the relay was only 1.8% off from the necessary value, it was an overreaching relay that would have tripped after the primary relay set detected a fault and tripped and it was only out of calibration for 98 days.
Mississippi Delta Energy Agency (MDEA), Docket No. RC12-15 (August 31, 2012)
Reliability Standard: PRC-023-1
Requirement: 1/1.1
Region: SPP RE
Issue: On September 8, 2011, MDEA, a TO, self-reported a violation of PRC-023-1 R1.1 because one of its two load-responsive phase protection systems, its SEL311C relay, did not meet the criteria set forth in PRC-023-1 R1.1 through 1.13. The proper setting for the SEL311C relay is 150% of the highest seasonal Facility Rating of an applicable circuit, determined by gauging the defined loading duration over the nearest four hours. On July 1, 2010 through June 8, 2011, the proper setting should have been 1,350 Amps; instead, MDEA operated its SEL311C relay at 1,343 Amps, 7 Amps below the level required by 1.1.
Finding: SPP RE determined that this issue did not pose a serious or substantial risk to the reliability of the BPS because the difference between the proper and actual settings was negligible. MDEA’s single 23 mile 230 kV transmission line could have been prematurely tripped by the incorrect setting, but the trip would have occurred based upon a line loading within less than 1% of the proper amp setting under 1.1. Consequently, the improper setting would not significantly limit the loadability of the MDEA transmission line or interfere with the relay’s protection of the MDEA transmission line from a fault.
Virginia Electric and Power Company, (VEPCO), Docket No. RC13-8, April 30, 2013
Reliability Standard: PRC-023-1
Requirement: 1
Region: SERC
Issue: In preparation for an upcoming Compliance Audit, VEPCO filed a self-report in December 2012 explaining that a set of relays on its Chesterfield Line 208 was incorrectly set to operate at 110.31% rather than at least 150% of the highest seasonal Facility Rating of the circuit due to a discrepancy between the relay control drawings and the relay setting documentation. .
Finding: The violation was deemed to pose minimal risk to BPS reliability but not serious or substantial risk which was mitigated because subsequent investigation determined that the relevant line has never exceeded 60% of the highest seasonal rating showing that setpoints would not likely limit loadability under these circumstances.
Virginia Electric and Power Company, (VEPCO), Docket No. RC13-8, April 30, 2013
Reliability Standard: PRC-023-1
Requirement: 1
Region: SERC
Issue: In preparation for an upcoming Compliance Audit, VEPCO filed a self-report in December 2012 explaining that a set of relays on its Chesterfield Line 208 was incorrectly set to operate at 110.31% rather than at least 150% of the highest seasonal Facility Rating of the circuit due to a discrepancy between the relay control drawings and the relay setting documentation. .
Finding: The violation was deemed to pose minimal risk to BPS reliability but not serious or substantial risk which was mitigated because subsequent investigation determined that the relevant line has never exceeded 60% of the highest seasonal rating showing that setpoints would not likely limit loadability under these circumstances.
