In a normal situation, the first fault would have triggered the fuse in the voltage transformer and cut off electric current, said LTA and SBS Transit.
“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,” they said.
As a result, the high current surge damaged Switchboard 2.
As the two switchboards were connected, the high current surge from the fault caused Switchboard 1 to disconnect from the system to avoid damage.
With one switchboard damaged and the other disconnected, power supply to parts of the NEL and the Sengkang-Punggol LRT was cut off.
Services on NEL and Sengkang-Punggol LRT were “progressively restored” on the same day using a backup power supply, said LTA and SBS Transit.
However, Switchboard 2 could not be repaired immediately “due to the extensive damage”.
“As Switchboard 1 was protected from damage, it was reconnected to allow normal service to resume the next morning.”
Repairs to the voltage transformer and Switchboard 2 were completed on Saturday.
