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SINGAPORE – All power lines along the Tuas West Extension will be replaced after a massive three-line failure that left more than 6,700 passengers stranded on trains stranded for up to three hours on October 14.
In a joint briefing with rail operator SMRT and systems provider Alstom on Wednesday (Oct 28), the Land Transportation Authority said that Alstom will replace some 150 km of cables that supply power to trains by the end of 2021.
The replacement cables will have stronger insulation, the French company said.
Alstom will also replace the 113 trip coils, core components of circuit breakers, along the three-year western stretch of the East-West MRT line by the end of this year.
The company will do so at its own cost, which it did not disclose.
SMRT said the October 14 breakdown during the afternoon peak affected about 123,000 travelers: 110,000 on the North-South and East-West lines for three and a half hours; as well as 13,000 passengers on the Circle Line for just over an hour.
The massive outage dates back to a burned section of cable between Tuas Link and Tuas West Road stations.
The fault should have been isolated by circuit breakers in the vicinity, but one didn’t trip as designed due to a faulty trip coil.
This caused a secondary protection system to trip, cutting off the power supply from a Tuas substation to a stretch of stations along the North-South and East-West lines.
SMRT then decided to take power from an alternative substation in Buona Vista.
But it did so without first isolating the power failure at Tuas and thus allowed the power failure to affect the circular line.
SMRT CEO Neo Kian Hong said a staff member and supervisor had misread the equipment at the substation and thought the fault had been isolated.
The two have since been suspended from their duties, he added.
The briefing revealed that four similar cable faults had been detected since the West Tuas Extension opened in 2017.
These earlier failures did not cause a widespread outage because the circuit breakers intended to isolate them worked, the LTA said.
He raised the issue of faulty cables with Alstom in January this year, and the contractor agreed to replace the top layer of cables. Replacement work was due to begin in October.
SMRT’s Neo had also said that the firing coils along the affected stretch were last checked on October 6, just a week before the massive breakdown.
The LTA said there will be an early closing and late openings on weekends starting next month to make it easier to replace the firing coil.
Full-day closings on Sundays may also take place next year when cable replacement takes place.
The LTA said the affected cables were of similar design and made by the same manufacturer as those in other parts of the MRT network.
Circuit breakers are also “established design” and are widely used in the power industry.
For its part, SMRT said it will now test circuit breakers every six months instead of 12. The operator added that it will “improve procedures for energy recovery” so that the human error that allowed the October 14 failure to spread. to the circular line “. will not be repeated”.
This is not the first time that relatively new line power cords have been replaced. In 2012, when the Circle Line was around three years old, 120km of its cables, also laid by Alstom, were replaced with more waterproof cables at a cost of $ 15 million.
Most of the replacement cost was borne by Alstom.
At Wednesday’s briefing, the French contractor said it was still investigating what caused the trip coil and cable failure.
New LTA CEO Ng Lang, with just over a month on the job, said the breakdown was a stark reminder that work to maintain the reliability of the rail system was a never-ending journey that could be interrupted by failures. smaller.
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