Malfunction of power cable's insulation led to major train breakdown: SMRT

A BREAKDOWN of insulation of a power cable between Tuas Link and Tuas West Road stations was the culprit behind the major MRT breakdown during peak-hour traffic on Wednesday evening, based on preliminary findings.

"A circuit breaker at Tuas West Road station should have kicked in to isolate the fault, but it did not, resulting in the NSEWL (North-South, East-West lines) power system to trip," said SMRT in a statement on Thursday.

To restore power to the NSEWL, there was an attempt to draw power from Buona Vista Intake (BVI) substation.

However, this was done without first isolating the fault, leading to a power supply disruption to the Circle Line, which the BVI also serves.

As a result, this led to a disruption in services along the NSEWL from Woodlands to Jurong East and Queenstown to Gul Circle, as well as along the Circle Line from Harbourfront to Serangoon.

The insulation fault has since been identified and isolated, and the faulty component of the circuit breaker has been replaced, SMRT said.

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"We are working with LTA to conduct a full investigation into the premature failure of these components, together with the original equipment manufacturers who supplied the parts," it added.

Train services resumed normal operations on Thursday.