Cookie Consent by CAF’S ACR for catenary-free trams
Home · Spanish Railway News   Home     What is Vía Libre?     Site map     Legal information     Contact  
Spanish Railway Foundation
Home Industry news Spain abroad Technology Operators Infrastructure All bulletins
Print Article Send by email
CAF’S ACR for catenary-free trams

Construcciones y Auxiliar de Ferrocarriles (CAF) has developed an innovative on-board energy storage system that eliminates the need for catenary cables between stops in urban areas. Through the use of this technology, CAF intends to contribute to the better integration of urban transportation within cities, by reducing the environmental and visual impact in historic city centers and increasing energy efficiency.

CAF’S ACR for catenary-free trams

(09/02/2011)  Free-catenary autonomous circulation is a solution to the growing demand for public transportation networks that are better integrated in their cities, more environmentally-friendly, and comfortable for passengers.

The “Rapid Charge Accumulator” (ACR), based on ultracapacitor technology, will allow vehicles to circulate without cables between stops. Furthermore, no special facilities or extra investment are required.

This unprecedented highly-innovative technology will contribute to the better integration of urban transportation within cities, by reducing the environmental and visual impact in historic city centers and increasing energy efficiency.

One of the main advantages of this innovative condenser is its compatibility with other technologies and “its applicability to rolling stock of any type and manufacturer, as well as to new or already-existing infrastructures.”

Another significant advantage of the system is that it is “clean, safe and reliable, easy-to-install and maintain, and cost-competitive.”

In addition to catenary-free operation, this system also recovers the maximum amount of energy during braking, which is very frequent in cities. While conventional trams only recover energy when the catenary allows it, the ACR accumulator guarantees full recovery. An additional advantage is the autonomy of the system in emergency power shortages.

The Rapid Charge Accumulator is one of the main novelties in the third-generation series of trams and light rails URBOS.


border=1The ACR project developed by CAF in conjunction with Trainelec (a CAF group company), is an on-board energy storage system based on the use of ultracapacitors which enables trams to run between stops without catenaries, as well as to save energy through the full regeneration of braking energy.

This system is compatible with other technologies and suitable for use on rolling stock of any type and manufacturer, and on new or existing facilities and infrastructure.

The ACR system is efficient and energy saving in catenary powered operation-

• Energy saving and reduction of current peaks in catenary powered operation.

• Maximum energy regeneration from braking processes.

ACR offers a safe running range in emergency situations in the event of sudden power failures.

It is catenary-free Operation-

• Temporary (1 section between stations due to power line failure).

• Permanent (several consecutive sections between stations).

• Up to 1,000 metres of catenary-free running range, depending on route characteristics, required performance and installed capacity.


 Catenary-free operation between stations.

 Energy saving (brake regeneration).

 Up to 1,200 metres of catenary-free running range depending on route characteristics between stops or incidents on the line.

 Modular and scalable.

Suitable for use on existing Systems.

 Twenty second charge times, compatible with stopping times at stations.

 Non-captive system (material/infrastructure independent).

 High development potential.


 Capacitive Storage.

 Charging and discharging by physical processes.

 Free from chemical reactions.

 Scalable by series/parallel extension.

 High speed recharge.

 Very high capacity cells.

 High energy and power density.

 Double electrode layer for higher capacity.


Controlled by the Traction Inverter.

Integrated into the on-board computer network.

Increased power compared with other storage Systems.

Minimization of brake resistors.

Protection against energy discharge to guarantee arrival at a charging point.



Print Article Send by email

© Vía Libre - Spanish Railway Foundation • All rights reserved 2024