Power failures struck Utah on Tuesday and early Wednesday, the first leaving a few businesses in Salt Lake City without electricity for up to an hour, the second taking Utah Power generating plants out of commission for a time but causing no local outages.
The Tuesday incident started when a connection failed in a substation at 147 S. 400 West shortly before noon Tuesday. A part that attaches a small underground power cable to equipment in the substation malfunctioned, said Utah Power spokesman Dave Eskelsen. The connections age and sometimes fail, he said.The outage that resulted lasted longer in some places than it took to replace the damaged part. "Some of the circuits didn't come back on like they should have . . . particularly to the newspaper area and Social Hall Avenue," he said.
The cold, wet weather made equipment sluggish in coming back on line.
That failure caused some anxious moments.
Diners in ZCMI's Tiffin Room gasped as they were plunged into complete darkness for a few moments. Then the lights came back on, and they resumed their lunches. Shortly after that, the electricity went off again and another gasp swept through the restaurant. But that was only a momentary outage, and the piano player barely missed a note as she resumed playing.
Other businesses were not so lucky. At the Deseret News, lights were off for about an hour and the presses were not able to print papers (see related story on Page B1).
Then early Wednesday morning a 500,000-volt direct current line serving northern California failed. This cut off power to an estimated 1 million customers in California and another 100,000 in Seattle, according to the Associated Press.
It also triggered disruptions in other states connected to the power grid, including Utah. Altogether, eight Western states were affected.
No Utahns were left without electricity during the regional failure Wednesday, which began about 1:25 a.m. But Utah Power generating plants in Utah and Wyoming were knocked out by the disturbance, and several hundred northern Wyoming residents - Utah Power customers - were without electricity for a few hours.
When the 500,000-volt line malfunctioned, protective equipment sensed a power surge throughout the grid. Otherwise, electrical equipment and the power system itself would be damaged by excess power.
"These facilities are pretty sensitive to disturbances on the system. When something like this happens, because the utilities are interconnected, all of these protective devices sometimes go off," Es-kel-sen said.
Protective equipment automatically shut down these Utah Power generating plants: the Hunter Plant units one and three near Castle Dale, Emery County; the geothermal plant at Lynndyl, Millard County; the Naughton Plant near Kemmerer, Wyo.; and the Dave Johnston Plant near Casper Wyo.
"It takes a couple of hours to bring a generator back on line," Eskelsen said. By about 4 a.m., all parts of the Utah Power system were restored.