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SINGAPORE: An inherent manufacturing defect or poor handling during installation likely caused power cable failures, resulting in the interruption of the three-line MRT last October affecting more than 120,000 travelers.
Transportation Minister Ong Ye Kung announced on Wednesday (March 17) the findings of the Land Transportation Authority on the October 14 outage that halted train services on the North-South Line between Woodlands and Jurong stations. East, the East-West Line between Queenstown and Gul Circle stations. and the Circle line between Serangoon and Harbourfront stations.
Passengers had to leave the trains stopped and walk along the tracks to nearby stations. Bus stops also filled up as commuters rushed to continue their bus trips.
The interruption affected 15 trains and 123,000 travelers.
READ: MRT outage on Oct 14 triggers system overhaul, with early weekend closures starting in November
READ: Timeline: How a power failure caused an hour-long outage on three MRT lines on October 14
Speaking at the inauguration ceremony of the Integrated Train Testing Center (ITTC), Mr. Ong said that a simultaneous failure of the feeder cables and trip coils along the Tuas West extension had caused the outage.
An inherent manufacturing defect or poor handling during installation caused a cut in the insulation layer, resulting in a short circuit, he said.
Meanwhile, the firing coils failed because one of the components, a plunger, had rusted.
“The plunger moves to allow the circuit breaker to trip when there is a fault. However, rust on the plunger obstructed the movement of the plunger and this caused the circuit breaker to malfunction,” Ong said.
He added that forensic investigations showed that an inadequate protective coating, likely specific to a particular manufacturing batch, had likely caused the plunger to rust.
RECTIFYING FAULTS
Since December, supplier Alstom has started replacing the 22 kV power cables along the Tuas West Extension with higher specification cables, Ong said.
It started with the section along Tuas Depot Intake and Tuas Link Station. To speed up the replacement, LTA had decided on full closures on Sundays from March 14 to May 23 at select stations along the Tuas West Extension, he said. Bridge bus services will be provided during closings.
READ: Human error aggravated MRT disruptions on Oct 14: Ong Ye Kung
LTA has also changed all the trip coils after the October outage, but will replace the trip coils again with an improved design made of stainless steel by the third quarter of next year, Ong added.
“To further ensure that moisture does not increase the likelihood of oxidation, LTA has also adjusted the space heater settings to reduce the level of moisture inside the circuit breakers,” he said.
While waiting for the change, SMRT has increased the frequency of the maintenance regimen to every three months, he added.
“When something goes wrong … it is very natural for us to explain ourselves, to tell others that we have done what we can,” Ong said.
“But even so, therefore, we must always know that we always take collective responsibility and that only by working together, addressing the blind spots and deficiencies of others, can we offer a better system.”
