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Commencement of NSEWL power supply renewal works

In a press release on Friday (5 October), the Land Transport Authority (LTA) and SMRT shared that the works to renew and enhance the North-South and East-West Lines’ (NSEWL) power supply system is expected to be completed in the early 2020s.

The power supply renewal works, the fourth core renewal project, which will start in October 2018, will make use of additional engineering hours from the scheduled Early Closures and Late Openings over the coming months.

These works are part of LTA and SMRT’s multi-year asset renewal programme for the NSEWL.

The replacement of wooden sleepers and the third rail were completed in December 2016 and September 2017 respectively, while the transition of the NSEWL to the new Communications-Based Train Control (CBTC) signalling system is progressing well.

The authorities also stated that enhancement works will also be carried out concurrently to improve the system’s resilience to enable better prediction of faults, thereby shortening recovery timeframes during a disruption. About 1,300km of power cables, 250km of fibre optic cables located along the NSEWL’s tracks, 206 power transformers, 172 switchboards and equipment in 171 sub-stations will be replaced.

To enhance SMRT’s predictive maintenance regime, a condition monitoring system will be implemented for the NSEWL, LTA noted.

The system will monitor the health of the power supply equipment and generate trend reports. Real-time information such as voltage and temperature will be transmitted to the SMRT’s operations control centre, so that irregularities can be picked up early, enabling SMRT to carry out further investigations and rectification works where necessary.

According to the authorities, the current 64P touch voltage protection system will also be replaced with Voltage Limiting Devices (VLD). Traditionally, the 64P system halts operations when the touch voltage of the railway is elevated, triggering safety mechanisms to kick in.

With the installation of the new VLD, the touch voltage will be mitigated without affecting rail operations. The NSEWL’s high voltage network will also be reconfigured to ensure that no single point of failure will disrupt the entire rail network.

Disconnector switches will also be installed to compartmentalise the rail network power supply, which means that in the event of a power substation failure, the fault will be localised, minimising disruption to other stretches of the same train line.

This is a more effective and efficient way of allowing the operator to quickly isolate, identify and rectify faults and bring back partial or full passenger services as soon as practicable, LTA said.

Authorities said that to minimise the impact of these major renewal works on commuter service, back-up standby generators and mobile substations will be deployed. In addition, critical migration works such as putting new switchgears into service, will be scheduled to take place on weekends. As an added precaution, the new power supply system will only kick in after extensive testing by LTA and SMRT.

The renewal of the power supply system for the NSEWL is a complex but essential project to improve performance. More Early Closures and Late Openings of MRT stations along the NSEWL will give the project teams additional time to carry out the upgrading works.

"We will keep commuters informed on the works regularly and seek their understanding," authorities added.