Tuesday's massive early morning blackout across multiple estates in Singapore was caused by the tripping of two power generating units one after the other, the Energy Market Authority (EMA) said on Wednesday, Sept. 19.

The two power generating units are one at Sembcorp Cogen and the other owned by Senoko Energy.

Explanation

Preliminary investigations are not yet conclusive, but the EMA has come out to explain what happened.

EMA said the cause can be traced to one power generating unit tripping, which led to the other to trip as it ramped up power generation to meet demand:

"Our preliminary findings show that on Sept. 18, one of the power generating units at Sembcorp Cogen Pte Ltd (Sembcorp) tripped. The stability of the power system requires the electricity supply to constantly meet electricity demand. When a power generating unit trips, the other units in operation will increase their electricity supply automatically."

"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."

Investigations still ongoing

So far, this is the only information released as the authorities are still looking into finding the cause of the first power generating unit going down:

"Investigations are still ongoing and EMA is working with Sembcorp, Senoko and their equipment suppliers to establish why the units tripped."

"We will also look into additional measures that can be put in place to minimise the recurrence of such incidents."

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Some 146,500 residents were affected by the blackout.

Housing estates across the island were hit by the supply cut, extending north, south, east and west of the country: