Shell spokesman Ray Fisher said the refinery had returned to normal operations.

A motor on the alky unit, which converts refining byproducts into octane-boosting components of gasoline, lost power on Thursday, causing the unit to trip out of production, the sources said.

The refinery restarted the 92,000-bpd gasoline-producing fluidic catalytic cracking unit (FCCU) on Sunday after an 11-week shutdown, the sources said.

The alkylation unit, which operates in tandem with the FCCU, restarted on Monday.