PUBLISHED ONAugust 17, 2025 5:16 AMBYCandice CaiThe disruptions to the North East Line and the Sengkang-Punggol LRT (SPLRT) lines on Aug 12 was due to a "double fault" scenario which occurred in a voltage transformer for one of two interconnected switchboards at the Sengkang Depot Substation — an occurrence described as "rare".
The Land Transport Authority (LTA) and SBS Transit (SBST) said this in a statement on Saturday (Aug 16), providing updates on the power fault incidents which occurred on Aug 12 and Aug 15.
In the case on Aug 12, which occurred at 11am and lasted for about three hours, the two faults occurred at the voltage transformer for Switchboard 2, the statement read.
The first involved a high current surge due to a fault in the voltage transformer, while the second was a dislodged cable connecting to the voltage transformer.
"In a normal situation, the first fault would have triggered the fuse in the voltage transformer and cut off electric current. However, in this situation, the dislodged cable came into contact with the metallic surface of the voltage transformer panel and allowed electric current to continue to flow, despite the fuse having been blown," said LTA and SBST.
The high current surge damaged Switchboard 2, and as the two switchboards were connected, this caused Switchboard 1 to disconnect from the system to avoid damage, they added.
As a result, power supply to parts of the NEL and SPLT were cut off.
Services to both NEL and the SPLRT were progressively restored the same day using a backup power supply, but due to the extensive damage, Switchboard 2 could not be repaired immediately, according to the joint statement.
As Switchboard 1 was protected from damage, it was reconnected to allow normal service to resume the next morning.
LTA and SBST added that repairs to the voltage transformer and Switchboard 2 were completed on Aug 16.
For the Aug 15 incident, which disrupted service for around four hours on the Sengkang-Punggol LRT system, a power cable fault was the cause.
The fault had occurred between Farmway and Kupang stations on the Sengkang LRT.
"In normal circumstances, Switchboard 2 at Sengkang Depot Substation could have been used to provide backup power, but since it was still out of service from the incident on Aug 12, the power cable fault caused the entire network to lose power," the statement read.
Service progressively resumed during the afternoon after power was restored.
LTA and SBST stated that they are still investigating the cause of the cable fault.
Their engineers are also testing 28km of cables along the entire SPLRT network to assess their condition. The tests are expected to be completed by Aug 23 as they can only be carried out during engineering hours.
LTA will also be implementing a secondary power supply source directly from the SP Power Grid, to be completed by the fourth quarter of 2025, as part of the Sengkang Depot expansion works.
"For the longer term, LTA is also working with SBS Transit to make further upgrades to the power supply for the NEL and SPLRT," the joint statement read.
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candicecai@asiaone.com
