SINGAPORE: A faulty voltage transformer at a substation in Bright Hill was the likely cause of the power failure that hit parts of Singapore on Jan 26, according to preliminary investigations by the Energy Market Authority (EMA).
Speaking in Parliament on Tuesday (Feb 12), Senior Minister of State for Trade and Industry Koh Poh Koon said the faulty transformer had started a fire at the substation, after which electrical protective devices were activated to isolate the fault so that the downstream equipment would not be damaged.
This resulted in the cut in power to the affected consumers, he added.
Around 27,000 consumers in Ang Mo Kio, Bishan, Sin Ming, Toa Payoh and Thomson were affected by the power cut, which occurred at 1.30pm on Jan 26.
SP Power Grid was able to restore electricity supply to 80 per cent of the consumers in 30 minutes. Supply for the remaining consumers was restored within 90 minutes.
"This is the first power failure incident involving a faulty voltage transformer in the past five years," said Dr Koh, who was speaking in reply to Non-Constituency Member of Parliament Leon Perera, who had asked about the extent and reasons behind the power disruption.
Mr Perera had also asked about the trend in the occurrences of such power failures over the past five years and the steps taken to minimise such incidents moving forward.
"Our power system remains one of the most reliable in the world," said Dr Koh. "Over the past six years, Singapore’s average annual disruption per consumer ranged from 12 seconds to 4.2 minutes, which includes the most recent incident."
"In comparison, major cities such as Osaka, New York, Hong Kong and London experienced an average disruption per consumer of between 5 minutes and 21 minutes in FY17."
Dr Koh said that the EMA will thoroughly investigate each incident and take appropriate regulatory action if necessary.
SP Power Grid has since adopted a higher frequency of condition monitoring for the specific equipment that had failed and will prioritise the replacement of that component in future maintenance works at substations.
An internal investigation committee has also been set up by the national grid operator to look into this incident, added Dr Koh.
Other steps taken by SP Power Grid include getting experts from the original equipment manufacturer to advise on the causes of the failure, as well as engaging Japanese utilities provider Chubu Electric to act as an independent expert in reviewing the findings and recommendations from the equipment manufacturer.
In his supplementary questions, Mr Perera asked again if there had been any trends observed in recent power disruption incidents, as well as if there were systemic issues that needed to be addressed and a protocol that stipulated how quickly power must be resumed in the event of a disruption.
Dr Koh said that SP Power Grid’s distribution control and customer service, for instance, monitors and controls the distribution network around the clock to ensure that electricity supply can be restored quickly - typically within three hours – in the event of disruptions.
Various preventive maintenance works are also carried out, alongside periodic maintenance, he added.
On whether power failure incidents have seen any trends over the past five years, Dr Koh said: “We will be worried about a trend if the same component or the same system within the electrical grid across different substations fail repeatedly.”
“While there may be a couple of incidences that happened in the recent past, they affect different parts (and) components for which the original equipment manufacturers are still looking at it."
He added: "Until the investigations are complete, I will not draw any premature conclusion to say there is a trend linking all these different equipment and different components together."