BLACKOUT: Two generators at Sembcorp and Senoko identified as source of power trips; cause being investigated

SINGAPORE — The massive blackout early Tuesday (Sept 18) morning was due to power trips at generator units at Sembcorp Cogen and Senoko Energy, according to preliminary findings by the Energy Market Authority (EMA).

One of the power generating units at Sembcorp had tripped, the EMA said in a statement on Wednesday. As a result, the power generating unit owned by Senoko Energy had been ramping up additional supply. “When a power generating unit trips, the other units in operation will increase their electricity supply automatically,” the EMA explained.

“The stability of the power system required the electricity supply to constantly meet electricity demand,” the regulator added.

“Subsequently, one of the power generating units owned by Senoko Energy Pte Ltd (Senoko) tripped while it was ramping up additional supply.”

The tripping of the two power generating units resulted in insufficient electricity supply to meet demand.

The protection devices in the power system then automatically disconnected electricity to some 146,500 households and businesses to rebalance the system.

The EMA added that it then instructed other standby power generating units, including unaffected units from Senoko and YTL PowerSeraya, to provide additional electricity supply.

“The restoration of electricity supply was done in a controlled manner to ensure the electricity system remained stable. As electricity generation increased, supply to consumers was progressively restored over 38 minutes,” said EMA.

Investigations as to what caused the power trips are ongoing.

The energy market regulator added that it will look into additional measures that can be put in place to minimise the recurrence of such incidents.

The early morning massive blackout hit 19 estates across the island. The areas affected were Boon Lay, Chua Chu Kang, Clementi, Jurong, Pandan Loop, Aljunied, Geylang, Tanjong Rhu, Mountbatten, Kembangan, Bedok, East Coast, Ang Mo Kio, Bishan, Thomson, Mandai, Admiralty, Sembawang and Woodlands.

It was the second major power outage in three months that has happened here. Earlier in June, more than 3,000 people were affected by a power outage in the Central Business District which lasted for 34 minutes.

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