SINGAPORE - SMRT and the Land Transport Authority (LTA) have
identified three possible causes for the power trips on Tuesday
evening, which eventually led to a shutdown of the North-South and
East-West lines for over two hours during the evening peak
period.
After doing a walk through the tunnels, engineers found that the
insulation on two power cables along the North-South line were
damaged.
There was also a faulty voltage relay at the Kranji power
substation and water leakage along a section of the Tanjong Pagar
tunnel .
All these damaged components have been fixed or replaced, said
SMRT's managing director of trains Lee Ling Wee at a press
conference on Wednesday morning.
He added however that they could not be "100 per cent certain" that
these were the causes of the power trips and SMRT engineers will
continue to check through the system after revenue service on
Wednesday.
On Wednesday morning, trains were running as per usual at headways
of two minutes during the morning peak period.
While the operator had planned to shut down service from 11am to
4pm, they found that trains were running smoothly and decided to
continue service as per normal throughout the day.
Mr Lee at the press conference also explained what happened on
Tuesday evening leading up to the disruption.
At about 6pm, there were more than 20 counts of traction power
trips across the network. These were remotely reset by officers
manning the Operations Control Centre.
Power trips occur when the train system detects a surge of power in
the system and as a precautionary measure shuts down.
However around 7pm, there were three power trips that could not be
reset remotely and needed to be done at the station level.
As the cause of the power trips could not be isolated, SMRT decided
to shut down the NSEWL lines after detraining passengers at station
platforms, he said.
SMRT ran trains along the westbound and eastbound lines first and
found that trains could function smoothly but hit snags along the
north and southbound lines.