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



Variable Frequency Drive

Variable frequency drives are widely used to control the speed of ac motors.  This note looks at the mechanisms which enable drive units to control the...

Lighting - Lamps

Lamps are the essential part of any luminaire. These are the light generating components. Since the advent of electrical lighting in the middle of the...

How D.C. to A.C. Inverters Work

Traditionally generation of electricity has involved rotating machines to produce alternating sinusoidal voltage and current (a.c. systems). With the development...

Frame Leakage Protection

While not as popular as it once was, frame leakage protection does still have some use in some circumstances.  In essence frame leakage is an earth fault...

Operational Amplifier

The fundamental component of any analogue computer is the operational amplifier, or op amp. An operational amplifier (often called an op-amp,) is a high...

Capacitor Theory

Capacitors are widely used in electrical engineering for functions such as energy storage, power factor correction, voltage compensation and many others...

Cable Sheath and Armour Loss

When sizing cables, the heat generated  by losses within any sheath or armour need to be evaluated. When significant, it becomes a factor to be considered...

Induction Motor Calculator

Just added a page to the tools, which will allow you to calculate the synchronous speed, slip and rated torque for an induction motor. Not a particularly...

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...

What are you reading!

Reading is a bit of a hobby of mine and I"ve done a few off-topic posts in the past on this. Rather than continue doing the occasional post I thought ...

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