INGENIEUR
• Traction power collection, and
• Mobile electric rail traction vehicles.
The basic structure of traction power supply
system for Malaysia’s railway transportation
infrastructure projects are shown in Figure A1.
As can be seen, both DC railway and AC railway
systems source their traction power/energy from
TNB power supply system.
As illustrated in Figure A1, the DC traction
systems for the LRT/MRT are supplied from the
33 kV 3-phase network transformer rectifier
substations. The DC voltage is 750 V. For the KTMB
commuter/intercity express train service (ETS),
single-phase 25kV AC supply feeds the overhead
catenary system which is supplied from the singlephase 132/25kV transformer feeder substations.
As can be seen from Figure A1, the running
rails are used as return circuits for both AC and
DC railway systems. However, the measures for
earthing and bonding differ fundamentally.
In DC railway electrification systems, the
running rails are laid with a high impedance/
resistance to earth and to earthing systems, to
avoid the return current leaving the running rails
as stray currents, causing corrosion of metallic
components in close contact with the earth. Items
such as pipeline ̰