Authorities Work to Prevent Future Disruptions on Singapore’s LRT

The Land Transport Authority (LTA) and SBS Transit are taking measures to prevent a recurrence of the recent “double fault” incidents that disrupted services on the North-East Line (NEL) and Sengkang-Punggol Light Rail Transit (LRT) in Singapore. Such events are classified as rare, according to a joint statement issued by the authorities on August 16, 2023.

On August 12, power faults caused significant disruptions, with NEL services halted for approximately three hours and Sengkang-Punggol LRT services affected for around five hours. The situation worsened when Sengkang-Punggol LRT experienced another disruption on August 15, lasting about four hours.

Understanding the Power Faults

The issues began at the Sengkang Depot Substation, which has two interconnected switchboards designed to operate as backups. On August 12, faults occurred at the voltage transformer associated with Switchboard 2. Specifically, a high current surge was triggered by a fault in the voltage transformer, compounded by a dislodged cable that connected to it.

Under normal circumstances, this first fault would have activated the fuse, cutting off the electric current. However, in this instance, the dislodged cable made contact with the metallic surface of the voltage transformer panel, allowing current to continue flowing despite the blown fuse. This anomaly resulted in damage to Switchboard 2. Due to the interconnected nature of the switchboards, the surge caused Switchboard 1 to disconnect to prevent further damage, leading to a power outage affecting parts of the NEL and Sengkang-Punggol LRT.

LTA and SBS Transit indicated that services were progressively restored on the same day using a backup power supply, but repairs to Switchboard 2 could not be completed immediately due to the extent of the damage. Fortunately, Switchboard 1 was protected and reconnected, enabling normal service to resume the following morning.

Additional Disruptions and Investigations

On August 15, another power cable fault occurred between Farmway and Kupang stations on the Sengkang LRT, leading to a complete loss of power across the network. The authorities noted that Switchboard 2, which could have provided backup power, remained out of service due to the earlier incident.

Repairs to the voltage transformer and Switchboard 2 were finally completed on August 16, allowing for the restoration of normal operations. However, LTA and SBS Transit are still investigating the cause of the latest cable fault. Their engineers are conducting tests along approximately 28 kilometers of cables in the Sengkang-Punggol LRT network to assess their condition. These tests are expected to be finalized by August 23, 2023, as they can only take place during designated engineering hours.

The LTA and SBS Transit are committed to ensuring the reliability of the transport network and are actively working to prevent future incidents that could disrupt services for commuters.