02-19-2016 BPU RPT 11 - Laserfiche WebLink

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RIVERSIDE PUBLIC UTILITIES Board Memorandum BOARD OF PUBLIC UTILITIESDATE: FEBRUARY19, 2016 ITEM NO : 11 File ID –16-0489 –D SUBJECTCASA BLANCA SUBSTATION TRANSFORMER OUT-OF-SERVICE UPDATE AND : PLANS FOR RESTORATION ISSUE : The issue for Board of Public Utilities considerationis awareness of the Casa Blanca Substation (Casa) transformer which was removed from service, current status, and the plan for restoration. RECOMMENDATION : That the Board of Public Utilitiesreceive and file this report. BACKGROUND : The Casa Blanca Substation islocated near Madison Street and Indiana Avenueand supplies electricity to the surrounding area. Casa Blanca Substation Transformer 1 (T1) was manufactured by ABB Group (ABB) and commissioned in October 2012 as part of the Casa Blanca Power project. This transformer changes transmission voltage to distribution voltage, weighs 136,275 lbs.and contains 5,359 gallonsof oil. In October 2013, during a routine dissolved gas analysis (DGA)test, T1 was found to be producing some abnormal gasses potentially indicative ofan internal problem. T1 was re-tested and in February 2014 the results showed an increase in the generation of key gases. T1 was taken out of service and ABB was notified. ABB’s on-site inspection and extensive testing did not positively identify the source of the gasesand determined it safe to return to service. After ABB’sinspection was completed, the transformer was returned to service in April 2014. RPU staff monitored this transformer monthly and it operated without further incident until December 3, 2015. On December 3, 2015, the routine DGA results for Casa T1 showed alarmingvalues of abnormal gases. A second oil sample was sent to another laboratory which validated the initial results. The transformer was immediately taken out of service. Stafftransferredthe customersnormally fedby T1 to adjacent distribution feeders with available capacityfromFreeman and Plaza Substations. This load transfer took place without affecting electric service to RPU customers. The transformer is under warranty until July2017. After consulting with ABB, RPU requested ABB ship the transformer back to theirfactory to perform all applicable diagnostic tests andrepairsto return it by April 30, 2016before summer loads increase. The T1 is currently in ABB’sfactory for repair. RPU staff is preparing several alternate plansfor use in the event ABB cannot return the transformer in a timely manner. These alternates include installingthe mobile substation trailer, moving the Plaza Substation T5 to Casa, and adding a T2 transformer at Casa.These solutionswill be refinedas additional information from the transformer manufacturer becomes available. Page 116