Introduction to Traction Substations 

By on

Following on from my post on railway electrification voltages, I thought an introduction to traction substations would be a good idea.

Traction substations are used to convert electrical power as supplied by the power utility (or rail operators own network) to a form suitable for providing power to a rail system (via third rail or overhead line). Depending on the type of rail system this power would be either direct current (dc) or alternating current (ac).

For dc systems, the traction substation core equipment will be the transformers and rectifiers to used to convert the utility supply to dc. Rectifiers are either 6, 12 or 24 pulse. In addition the dc traction substation will contain circuit breakers to ensure the system is adequately protected and switching devices allowing operation and maintenance of the system.

For ac systems, the traction substation core equipment will be transformers which connect to the three phase power utility supply to convert this to a single phase voltage suitable for the rail electrification system being used. Again circuit breakers and switching devices will be provided to ensure adequate system protection and operation and allow for maintenance.

Alternating current supply on the traction side is single phase and can lead to imbalance on the three phase utility beyond allowable limits. Balancing devices (Scott transformers, static convertors, etc.) are often used to achieve these limits.

Generally traction substations will be controlled by SCADA systems and will likely provide power for auxiliary systems such as signaling and other track side purposes.

Traction substations have harsher operational and stability constraints than normal power distribution substations. These include being subject to frequent short circuits, transient spikes, voltage depressions and voltage rises. The use of thyristor controlled traction drives generate significant harmonics, affecting the supply system.

Given the unique issues associated with rail power, the design, construction and operation of traction substations has many technical challenges. Add into this, loading from many trains running at the same time and modern design is heavily dependent on software support.

Please feel free to add comments below or suggest any items which you thing would be a good topic for a more detailed post.


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

  1. Sanjay's avatar Sanjay says:
    1/2/2013 6:08 AM

    Would like to kbnow about the traction substation equipment ararngements,layout,spacing and building foot print of the traction substation.What standards are followed for the traction substations?Is there any specific requirements laid by IEC in this regard?


Comments are closed for this post:
  • have a question or need help, please use our Questions Section
  • spotted an error or have additional info that you think should be in this post, feel free to Contact Us



Fault Calculations - Typical Equipment Parameters

A frequent problem in fault calculations is the obtaining of equipment parameters.  While it is always preferable to use the actual parameters of the equipment...

Understanding Circuit Breaker Markings

IEC 60947 is the circuit breaker standard and covers the marking of breakers in detail. Any manufacturer following this standard should comply with the...

Star-Delta Motor Starting - Performance

Many questions sent in to the site are in connection with motor starting and in particular star-delta.  For all but the simplest application, there is...

Getting Started with Patents

If you have a great idea or invent something the last thing you want is someone to steal the idea. One of the things you can do is protect the intellectual...

Aluminium Windings - Dry Type Transformers

The other day I was talking to a colleague who is a building services consultant.  Despite regularly specifying dry-type/cast resin transformers he was...

Capacitor Theory

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

Fault Calculations - Introduction

Fault calculations are one of the most common types of calculation carried out during the design and analysis of electrical systems. These calculations...

Multimeter

Multimeters are undoubtedly the most common item of electrical test equipment in use.  Often it is the first piece of equipment people will turn to when...

LED Replacement Light Bulb

The inventor of the first visible light-emitting diode makes history again this year as it begins to show customers a 40-watt replacement GE Energy Smart...

Questions - Reputation and Privilege

Our question and answer system while letting you do exactly what it says, is much more.  It is a dynamic user driven system, where our users not only ask...

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