03-14-2022 BPU RPT 07 - Laserfiche WebLink

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RIVERSIDE PUBLIC UTILITIES Board Memorandum BOARD OF PUBLIC UTILITIES DATE: MARCH 14, 2022 SUBJECT: CIRCUIT 1351 RELIABILITY IMPROVEMENT, FUSE COORDINATION PROJECT – WORK ORDER NO. 2201605 FOR A TOTAL CAPITAL EXPENDITURE OF $145,000 ISSUE: Consider approval of Work Order No. 2201605 for a total capital expenditure of $145,000 for the Circuit 1351 Reliability Improvement, Fuse Coordination Project. RECOMMENDATION: That the Board of Public Utilities approve Work Order No. 2201605 for a total capital expenditure of $145,000 for the Circuit 1351 Reliability Improvement, Fuse Coordination Project. BACKGROUND: Riverside Public Utilities (RPU) Electric System Planning staff performed a reliability study in order to improve the performance of Circuit 1351, specifically with a view to reducing outage time. Due to the numerous outages that have occurred on Circuit 1351, specific reliability improvements need to be performed. One of the improvements to be implemented is the overcurrent protective device coordination of Circuit 1351. The study recommends the reduction of fuse sizes on Circuit 1351 in order to coordinate with the substation breaker, thereby improving the System Average Interruption Duration Index (SAIDI) and System Average Interruption Frequency Index (SAIFI). The implementation would isolate any short circuit faults coming from a lateral line before it is sensed by the relay in the substation, and therefore avoid tripping the entire circuit at the substation. In addition, there are fuses on Circuit 1351with ampacities higher than some of their branch conductor’s ampacity. By making the fuse sizes lower than their branch conductor’s ampacity, the fuse will protect the conductors by opening the circuit if a fault causes too much current to flow on the lines. This excess current can cause damage to conductors and equipment could require a substantial amount of time to repair or replace. Outage time will be reduced by limiting conductor damage, thereby improving the Customer Average Interruption Duration Index (CAIDI), and overall system reliability.