Railway Electrification Voltages 

By on

This post is quick introduction and overview to different railway electrification voltages used in answer to a question sent in via email.

While there are numerous voltages in use through out the world (many dating back a hundred years), fortunately the number of voltages levels in common/widespread use is relatively few. To keep the post short, I will only list the more common voltages.

Both dc and ac systems are used. Direct current systems are generally used for metro lines and relatively commuter /regional systems up to around 100 km long. For longer and more heavily loaded routes, alternating current is generally used.

Direct Current (dc) Voltages

Most commonly used are 600/650 and 750 V. These are used world wide on mass transit, commuter and tram lines. Voltage is supplied to the train using a third rail or overhead lines.

1.5 kV (typically supplied overhead) is used in Europe, the US, China, Australia and a several other countries. Less common are 3 kV systems, but these can still be found in operation in several countries.

Alternating Current (ac) Voltages

25 kV (50 Hz or 60 Hz) ac systems have achieved widespread use in many countries, including the UK, US, large parts of Europe, Asia, Africa and the Americas. Additionally 15 kV (16 2/3 Hz) networks still have widespread use within Europe and the US still has several 12 kV (25 Hz) lines.

The US, South Africa and Canada also operate 50 kV systems in operation (typically used on systems for mine haulage).

It would be fair to say that 25 kV has become the international standard. This is covered by two standards:

  • BS EN 50163 - Railway applications. Supply voltages of traction systems
  • IEC 60850 - Railway Applications. Supply voltages of traction systems

Alternating current systems invariably are supplied by overhead lines. It is worth noting that most implementations are single phase (due to problems with picking up three phases from the overhead lines).  

That's it; a quick summary. It doesn't cover every voltage, but hopefully will give everyone a general understanding of the most common voltages used.

If anyone has anything to add or want to give a few more details, please do so below.

Steven McFadyen's avatar Steven McFadyen

Steven has over twenty five years experience working on some of the largest construction projects. He has a deep technical understanding of electrical engineering and is keen to share this knowledge. About the author

myElectrical Engineering

comments powered by Disqus

How Electrical Circuits Work

If you have no idea how electrical circuits work, or what people mean then they talk about volts and amps, hopefully I can shed a bit light.  I’m intending...

Generation of a Sine Wave

A fundamental concept behind the operation of alternating current systems is that voltage and current waveforms will be sinusoidal – a Sine Wave. This...

Three Phase Power Simplified

A single phase system is perhaps the most common type of system most people are familiar with. This is what people have in their homes and what appliances...

The dc resistance of conductors

This is the first of two posts on the resistance of conductors. In the next post I will look at the ac resistance, including skin effect and we deal with...

Lithium Ion Battery

Over recent years the Lithium Ion battery has become popular in applications requiring high power densities with small weight and footprint.  Today Lithium...

Earth Electrode Resistance

Earthing of electrical systems is essential for the correct functioning and the protecting of life and equipment in the event of faults.  The earth electrode...

Paths of Flight

GE have put together a time-lapse video shown flight take-off and landings at some airports. An interesting view:

Closed Doors

"I can live with doubt and uncertainty and not knowing. I think it is much more interesting to live not knowing than to have answers that might be wrong...

Robotics - Home Innovations

We have a sister note to this (Robots - Interesting Video), in which I have posted some videos of interesting robots developed by commercial corporations...

IEC 61439 Verification Methods

The (relatively new) switchgear and control gear standard, IEC 61439 'Low-voltage switchgear and controlgear assemblies' has three methods which can be...

Have some knowledge to share

If you have some expert knowledge or experience, why not consider sharing this with our community.  

By writing an electrical note, you will be educating our users and at the same time promoting your expertise within the engineering community.

To get started and understand our policy, you can read our How to Write an Electrical Note