NEL, SPLRT disruption Electrical surge shut down switchboard and its backup, according to LTA

This caused the power supply from Sengkang Depot to be cut off completely

- Kok Yufeng Transport Correspondent and Esther Loi

Early investigations into the Aug 12 disruption on the North East MRT Line (NEL) and the Sengkang-Punggol LRT (SPLRT) system have shed more light on the cause of the breakdown and why it took hours for operator SBS Transit to restore services on the affected lines.

The Land Transport Authority (LTA) said in a Facebook post on Aug 13 that a surge in electricity had damaged one of two switchboards at a substation in the NEL depot in Sengkang, which fed power to the affected rail systems.

At the same time, the electrical surge also triggered a safety feature meant to protect the second switchboard from damage, causing it to shut down as well, LTA noted.

A switchboard distributes power from electrical sources to several smaller circuits.

The authority said the two switchboards would normally have acted as backups for each other, so that power could continue to be supplied even if one were to go down.

But on Aug 12, the power supply from Sengkang Depot was cut off completely as a result of both switchboards tripping, and SBS Transit had to manually connect the second working switchboard to a backup power source in Dhoby Ghaut to restore train services progressively.

LTA said that while it continues to probe the incident, which was the second lengthy service disruption to hit Singapore's rail network in two weeks, it is also reviewing with SBS Transit how to make the power systems more resilient.