When Three Rivers was switched to portable power on Wednesday morning (Oct. 8), there was a brief, yet planned, system-wide outage that occurred at 9:05 a.m. when the 69 kilovoltage line from the Valley floor was disconnected. The huge generators that had been idling were switched on electronically and six minutes later the portable power restored electricity to the upper canyon.
At 9:27 a.m., power in the mid-canyon around the Dinely Bridge area came back on; 10 minutes later, power was restored to the central business area and lower canyon. According to a Southern Edison Company contracting project engineer, Three Rivers will be on portable power for the next 20 days.
The load at 10 a.m. was 1.7 megawatts, approximately 28 percent of capacity, but is expected to be much higher in peak periods when customers switch on air conditioners to cope with temperatures in the 90s. Other than a puff of black smoke when the diesel generators became fully operational, the moderate noise level nearby was the only impact to what Edison company officials hope will be a smooth transition to local use of the portable power.
Those outages and impacts were planned and expected. What occurred later that night was not expected and resulted from a problem at the Three Rivers substation. Power to all of Three Rivers went down at 10:12 p.m. and those fortunate enough to have a view of the Kaweah canyon were treated to a natural nightscape drenched in shimmering moonlight with no artificial light.
Power was restored to upper canyon customers at 12:07 a.m. and to the lower canyon at 12:19 a.m. The electricity went off system-wide again at 12:41 a.m. and was restored to the upper canyon at 1:53 a.m.
The lower canyon’s power, including central Three Rivers, was not restored until 3:40 a.m. Apparently, that power surge knocked out cell phone service and it remained down Thursday morning.
An SCE representative reached by calling the company’s outage-reporting phone number said there was no official cause for the equipment failure at the substation and the company is working throughout the upgrade project to minimize impacts of the portable power to its Three Rivers customers.
Technical information and chronology of the outages provided by Bill Pooley of Three Rivers.