April 15 (Reuters) - Hawaiian Electric urged Hawaii

Island's residential and business customers to conserve

electricity use on Monday due to several large generators being

unavailable.

The Honolulu-based electric utility said 21,557 customers

around the island experienced a 30-minute outage on Sunday night

starting at 8:54 p.m (0654 GMT on Monday) and ending at 9:59

p.m.

"Hawaiian Electric's Hill 5 steam unit tripped offline

yesterday. Puna steam unit and CT-1 combustion turbine unit also

are under repair," the company said.

Hawaiian Electric did not immediately respond to a Reuters

request for additional comment.

Last month, Hawaiian Electric asked its customers on Hawaii

Island to reduce or shift their electricity use through April

after the utility's largest generator went offline due to

mechanical issues.

Hawaiian Electric is facing multiple lawsuits claiming it

was to blame for a wildfire that tore through the island of Maui

last year, killing at least 100 people. A spokesperson for the

company said in September it does not comment on pending

litigation.

In November, the company said it was unable to submit its

quarterly filing with U.S. securities regulators on time due to

financial contributions it made towards victims of the wildfire.