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

Understanding electric motor insulation & temperature

Anyone specifying or using electric motors should have a basic understanding how the insulation is related to temperature. Three classes of insulation...

Laplace Transform

Laplace transforms and their inverse are a mathematical technique which allows us to solve differential equations, by primarily using algebraic methods...

Periodic Electrical Installation Inspection – What to Inspect?

This is the second post in a series of two on periodic electrical inspections. In the first post, I discussed how often inspections should be carried out...

Standard Cable & Wire Sizes

IEC 60228 is the International Electrotechnical Commission's international standard on conductors of insulated cables. Among other things, it defines a...

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...

Calculating Cable Fault Ratings

When selecting a cable, the performance of the cable under fault conditions is an important consideration. It is important that calculations be carried...

Photovoltaic (PV) - Electrical Calculations

Photovoltaic (PV) cells (sometimes called solar cells) convert solar energy into electrical energy.  Every year more and more PV systems are installed...

Cable Sizing Software

When sizing cables nearly, everyone uses some form of software. This ranges from homespun spreadsheets to complex network analyses software. Each has its...

IEC Document Designation

Often document control is dictated by project requirements, for example a particular organisation may have an existing numbering system. Existing company...

A mechanical engineering paper, some history and memories

I was digging in my bookshelf and came across the 80th Anniversary Association of Mine Resident Engineers, Papers and Discussions Commemorative Edition...

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