Hawaiian Electric Co. said today it has replaced a damaged transformer serving Ala Moana Center and should have normal systems running by Sunday morning in time for the day after Christmas shopping.

“We made significant progress,” said Darren Pai, HECO spokesman.

The new transformer will be tested on Christmas day, he said. If that goes as expected, Ala Moana will return to the normal configuration with a full set of automatic backup circuits, Pai said.

Dozens of stores at Hawaii’s largest shopping center were in the dark off and on since Sunday following the heavy rain that triggered an electrical fire and destroyed the transformer.