1500 V DC traction system for the North East Line

The North East Line (NEL) traction system is operating at 1500 V DC obtained from a 22 kV distribution network supplying 16 stations, a depot and a route length of 20 km. There are two power intake points from the PowerGrid, one at the Sengkang Depot (66 kV) and the other at the Stamford Intake (22 kV). Inverters are installed in some traction substations to convert excess DC power generated from trains' regenerative braking to the 22 kV AC network and improve the line receptivity. The power supply for a transit system is different from that supply to the normal electric network for other purposes. DC traction systems have elements of equipment, design or operational philosophy which are considered special. NEL is no exception and is unique by itself. Moreover, it is the first MRT line in Singapore using a 1500 V DC overhead catenary system instead of the 750 V DC third-rail collection system in the existing lines. This paper describes the NEL traction system from conceptualization to completion and the design considerations in terms of engineering, operational and maintenance requirements. The difficulties encountered during construction, testing and commissioning phases, and finally, experience gained in operation so far are also presented.