UPDATE 1-Chevron: L.A. refinery restoring coker ops

HOUSTON, May 14 (Reuters) - A coking unit at Chevron Corp's (CVX.N: Quote, Profile, Research, Stock Buzz) 260,000 barrel per day (bpd) Los Angeles-area refinery in El Segundo, California, was returned to planned rates on Wednesday night after an afternoon upset, the company said.

The coker's throughput was reduced after a controller problem developed on the unit, said Chevron spokesman Rod Spackman.

"We needed to slow the unit down to make sure we understood what was going on," Spackman said.

Once the problem was fixed, Chevron began returning the coker to planned rates, he said. The incident lasted about two hours.

A coker increases the amount of material that may be refined into motor fuels from a barrel of oil and turns the residual material into petroleum coke, which has a variety including as a fuel similar to coal. (Reporting by Erwin Seba; Editing by Michael Urquhart)