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How electricity powers rail systems

How Electricity Powers Rail Systems

  |   Electrification   |   No comment

When we use the local trains for our daily commute or even to travel longer distances or interstate, we hardly ever think about what powers the train or the technology that’s behind the functioning of the trains. Many of the current day trains as we know them, operate on electricity. This electrification process of the suburban networks in Australia commenced way back in 1919; but at that point of time, there wasn’t a standard or consistent electric rail traction used.

In 1919, electrification of the railways started in Melbourne, using the 1.5kV DC. Then in 1926, Sydney’s lines were electrified using 1.5kV DC. Brisbane followed in 1979; here 25kV AC was used and on its heels was Perth in 1992 with 25kV AC and Adelaide in 2014 with 25kV AC.

In Queensland, there has also been expansive non-urban electrification using 25kV AC; this was primarily for the coal routes, in the 1980s. Today, 25kV AC has been adopted as the international standard.

About how electricity powers rail systems

  • The electrification used to power rail systems supplies power to the trains & trams of the railway; no local fuel supply or on-board prime mover is required
  • There are numerous advantages to electrification, however the capital expenditure can be very high
  • The electrification system to be used is based on factors such as the economics of the power supply and the capital cost in comparison to the revenue generated by passenger and freight traffic
  • The systems used in intercity areas are different from the ones used in the urban areas and certain electric locomotives also have the flexibility to switch from varying supply voltages
  • The electricity generation takes place in efficient and large generating stations. These are then transmitted to the entire railway network & will also be distributed to all the trains that are running on the lines
  • In most cases electric railways acquire power from local electric utilities while others have their exclusive generating stations
  • Generally, the railway provides its own distribution lines, transformers and switches
  • An almost continuous conductor that runs along the tracks, supplies electricity to moving trains; this can be in either of the following forms:
    • An overhead catenary wire/line suspended from towers or poles all along the track – these could be suspended from a tunnel ceiling or structure too. The locomotives/multiple units then pick up the power from contact wires via the pantographs that are affixed to their roofs. Either air pressure or a spring is used to press the conductive strip against it
    • A third rail that’s mounted at the track level provides contact using a ‘pickup shoe’

Generally, both these systems use the rails as the return conductor; however some systems may also use a completely disconnected fourth rail for this purpose.

The benefits of electric engines in comparison to diesel engines

  • Higher energy efficiency
  • Lower operating costs
  • Lower emissions
  • Quieter and more powerful engines
  • Reliable and responsive
  • In some systems, the regenerative braking systems convert the kinetic energy of the train into electricity; this is returned to the main supply system and is used either on the general electricity grid or other trains

The disadvantages of electric traction

  • High capital costs which might not be financially viable for low traffic routes
  • Charging infrastructure at stations and onboard supercapacitors or electrified tracks are required
  • Power interruptions can affect operations
  • The through service can become complex due to variation in frequencies and voltages between regions
  • Track workers are at risk of electrocution due to the lethally high voltages on third rails and contact wires. While overhead wire installations are a safer alternative, the perception is that they mar the look of the system

Regardless of how you look at it, the advantages of electric rail systems outnumber the disadvantages and it has become the preferred method of powering locomotives in the modern day.

If you want to know more about electric rail systems or our custom made DC to DC converters and services, don’t hesitate to contact us at KaRaTec Power Supply Pty. You can give us a call at 612 9808 1127. You can also fill in this contact us form and we’ll reply as soon as possible.

Thanks for reading,
Karatec Power Supply Pty
612 9808 1127

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