The Land Transport Authority (LTA) appointed an Independent Advisory Panel (IAP) in December 2015 to review the power supply system for all MRT and LRT lines1. The IAP comprised international specialists in power supply systems, including representatives from an overseas operator and equipment design specialists. The IAP has completed its assessment of the power supply system.
Independent Advisory Panel’s Recommendations
2. The IAP recognises that the power supply system has achieved a high availability2, but recommends that the performance of the power supply system be assessed against a more holistic perspective of system resilience. The interdependencies between the power supply system and adjoining systems, such as trackways and trains, should be considered in operating and maintenance procedures. In the longer term, the IAP recommends that the design of the rail system should provide for a maximum downtime of five minutes during faults, with system recovery achieved within 20 minutes.
3. The IAP recommended the following measures to improve system resilience in the near-term:
(i) Foresight: Ability to anticipate, prevent and mitigate problems before they occur
The Panel recommends:
- Continuing to apply equipment specifications and codes of practice unique to Singapore’s operating environment, in addition to existing international standards and codes of practice
- Establishing condition monitoring to include power equipment to facilitate early fault detection and prevention
- Considering the replacement of critical power supply assets early, five years before the end of their specified lifespan
- Enhancing the maintenance regime for assets due for replacement until they are fully replaced
- Improving power supply system design to facilitate easier and more effective maintenance
(ii) System robustness: Ability to absorb disruptions or perform recovery actions without significantly affecting system performance
The Panel recommends:
- Establishing the Intelligent Fault Identification System (iFIS) which will allow operators to pinpoint exact fault locations quickly
- Reviewing protection systems so that they will trip only specific stretches when triggered, unlike the current 64P touch voltage protection system
(iii) Rapid recovery: Ability to restore full system performance quickly before a fault escalates into a high-impact power outage.
The Panel recommends:
- Enabling faster switch-over to an alternative power supply in the event of a loss of power supply
- Enhancing and streamlining incident response measures and recovery plans, and conducting exercises to hone the operators’ familiarity with these plans
- Improving the analysis and classification of causes of faults and establishing a database to facilitate fault diagnosis for future incidents
Measures to Improve Power System
4. Mr Chew Men Leong, Chief Executive, LTA, said: “We appreciate the thorough assessment of the Panel members to review the power system from an external perspective. LTA has already implemented some of these recommendations. For example, we have implemented Voltage-limiting Devices (VLD) on new lines from the Downtown Line onwards and will be retrofitting them onto existing lines. At the same time, we will also look at the other areas of improvement such as improving the recovery process to shorten the duration of an incident.”
5. To enhance the ability to anticipate and prevent problems before they occur, LTA and the operators are examining the implementation of predictive and condition monitoring tools such as insulation monitoring and testing, which will help pinpoint abnormalities for early intervention. LTA is also working with the operators on their replacement schedule for ageing power assets, as well as to step up their maintenance regime until the relevant power assets are replaced.
6. To enhance system robustness, LTA had successfully tested and is implementing the Intelligent Fault Identification System for the Downtown Line, Thomson-East Coast Line and future lines. LTA will be adopting the IAP’s recommendation to expand this technology to all existing lines. LTA is also working with operators to replace the existing 64P touch voltage protection system with the Voltage-Limiting Devices which will trip and isolate only specific stretches of the system where faults occur.
7. On the IAP’s recommendations for rapid recovery, LTA is working closely with the operators to review incident response measures and recovery plans, and will conduct technical exercises in a simulated live operating environment. We will also be working with the relevant agencies to examine ways to enable faster recovery of power supply in the event of a power failure, as well as with operators to establish a database of previous power faults.
8. With these recommendations, the LTA, together with the rail operators, is taking the necessary action to minimise power-related incidents and enhance overall rail reliability.
9. The executive summary of the IAP’s report can be viewed at /content/dam/ltagov/news/press/2016/20160419_IAPExecutiveSummary.pdf
1 Includes the North-South and East-West Lines, North East Line, Circle Line, Downtown Line, Thomson-East Coast Line, Bukit Panjang LRT and Sengkang and Punggol LRT systems
2 This is the amount of time the equipment is available to perform its function over the total time the equipment is needed.
