Switchboard that caused 12 Aug NEL & SPLRT disruption repaired on 16 Aug
A rare “double fault” scenario caused the hours-long disruption in services on the North-East Line (NEL) and Sengkang-Punggol LRT (SPLRT) on Tuesday (12 Aug).
This was revealed by the Land Transport Authority (LTA) and operator SBS Transit in a Facebook statement on Saturday (16 Aug), which explained how the incident had happened.
Source: Sophie Tay via Complaint Singapore on Facebook
Switchboard experienced 2 faults, was damaged
LTA and SBS said the Sengkang Depot Substation has two interconnected switchboards, which serve as back-ups for each other.
On 12 Aug, two faults arose at the voltage transformer for Switchboard 2:
- A high current surge due to a fault in the voltage transformer.
- A dislodged cable connecting to the voltage transformer.
Ordinarily, fault one would have blown the fuse in the voltage transformer and cut off the electrical current.
But this time, fault two — the dislodged cable — came into contact with the metallic surface of the voltage transformer panel, allowing the high current to continue flowing.
This damaged Switchboard 2.
To avoid being damaged, Switchboard 1 then disconnected from the system.
Source: Land Transport Authority – We Keep Your World Moving on Facebook
Rare ‘double fault’ cut power to NEL & SPLRT on 12 Aug
This “double fault” scenario, which LTA and SBS described as “rare”, cut off the power supply to parts of the NEL and the entire SPLRT on 12 Aug.
The NEL train service was unavailable between Farrer Park and Punggol Coast after 11am, with commuters reporting power outages at the affected stations.
Source: @nic2849 on Reddit
Full service along the NEL resumed about three hours later from 2.10pm, with a backup power supply activated.
However, Sengkang LRT service resumed only at 3.34pm, while Punggol LRT service progressively resumed with only one track from 4.15pm and returned to full service only at 9.10pm.
Switchboard 2 repaired on 16 Aug
As Switchboard 1 had not been damaged, it was reconnected so normal service could resume the next morning, according to the statement.
However, Switchboard 2 had suffered extensive damage and could not be repaired immediately.
Repairs to the voltage transformer and Switchboard 2 were carried out “expeditiously and safely”, and were completed on Saturday — four days after the incident.
Source: Land Transport Authority – We Keep Your World Moving on Facebook
SPLRT service disrupted again on 15 Aug
Before that, however, service on the SPLRT was disrupted again on Friday (15 Aug) morning.
This was caused by a power cable fault between Farmway and Kupang stations on the Sengkang LRT, LTA, and SBS said.
Because Switchboard 2 was still out of service, it could not be used to provide backup power.
Thus, the entire network lost power and service was unavailable from 8.40pm, according to a Facebook statement by SBS Group CEO Jeffrey Sim.
Commuters seen walking on LRT tracks
The second SPLRT breakdown in four days led to commuters being seen walking on the LRT tracks.
Source: @yinjiaen on TikTok
Mr Sim said 10 trains had stalled, with all passengers having to disembark. This “took some time” before recovery works could proceed.
He said the incident on 12 Aug had damaged the back-up switchboard, forcing the system to run only on the main and single switchboard.
It also led to a lengthier time for service recovery, he added.
Full service on the Punggol LRT resumed about four hours later at 12.32pm, while full Sengkang LRT service resumed at 12.54pm.
Cause of 15 Aug cable fault still being investigated
Moving forward, LTA and SBS said they are “working on how to eliminate a recurrence” of the rare “double fault” scenario.
As for the power cable fault on 15 Aug, the cause is still being investigated, with engineers testing 28km of cables along the entire SPLRT network.
Source: Land Transport Authority – We Keep Your World Moving on Facebook
The testing is expected to be completed by 23 Aug.
Upcoming power supply upgrades for NEL & SPLRT
Additionally, a secondary power supply source, direct from the SP Power Grid, will be implemented at Sengkang Depot by the fourth quarter of this year.
This will be part of the substation’s expansion works.
Further upgrades to the NEL and SPLRT power supply are also in the pipeline.
LTA and SBS thanked commuters for their patience and understanding.
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Featured image adapted from @nic2849 on Reddit and @yinjiaen on TikTok.
