Equipment failure caused blackout: Minister

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Power-generating units tripped despite being properly maintained: Dr Koh

Power-generating units at Sembcorp Cogen and Senoko Energy tripped one after the other on Sept 18 and caused the country's worst blackout in 14 years, yet both sets of equipment had been maintained properly.

The incident has prompted the Energy Market Authority (EMA) to work closely with the two companies and their original equipment manufacturers to establish the root cause of the equipment failure.

Senior Minister of State for Trade and Industry Koh Poh Koon told Parliament yesterday the breakdown occurred despite the units being maintained in accordance with the manufacturers' recommendations.

"This is an important point because the generation technology is used in other generating units in Singapore as well as globally, and what happened here could occur elsewhere," he said, noting the investigations will take time as the parts have to be sent for testing overseas.

Four MPs had filed questions on the blackout that occurred at 1.18am on Sept 18, plunging into darkness about 146,500 residential and commercial customers in 19 areas. Power was restored within 38 minutes.

Outlining the details, Dr Koh said that a total of 16 generating units had been operating then.

At 1.17am, a power-generating unit at Sembcorp Cogen tripped, likely due to an equipment fault.

"This triggered an automatic response by the other 15 units to increase their supply.

"This is usually not a problem, as each of the remaining units had to increase their supply by only about 5 per cent," said Dr Koh.


However, a unit at Senoko Energy tripped a few seconds later, when a different component failed.

This led to a further supply shortfall, which caused the protection devices in the power system to kick in as designed, automatically disconnecting electricity to about 146,500 consumers, mainly households, to rebalance the system, he explained.

EMA immediately instructed other standby generating units to provide additional electricity supply, he added, and once these additional units came online after about 15 minutes, electricity supply was restored progressively.

Dr Koh said: "We are reviewing our system to ensure that we continue to have sufficient capacity and contingency measures to handle any similar incidents in future."

The reliability of electricity supply has also not been affected by the liberalisation of the electricity market, he added, pointing out that the electricity sector relies on both regulatory powers and market incentives to keep generation companies on their toes.