23 September, 2019

More space, less cost

13 April, 2017

Train operators are looking to free up space in rail carriages to provide more comfort for passengers. That is resulting in the use of compact and versatile circuit protection technologies which can help maximise carriage layout configurations, while contributing to a reduction in total cost of ownership, writes Delphine Clement, Eaton EMEA rail segment manager.


Rising customer expectations in the railway industry means that train operators are looking for every available means of improving comfort on their services. One method of doing this is to reduce on-board equipment dimensions, therefore freeing up room for passengers in each carriage.

Increasingly, then, train designers are thinking long and hard about the choice of key systems and components, as they seek to delocalise and distribute certain functions to inaccessible places around the passenger car – in the roof, under the body or in hidden cabinets – to gain extra space. Such product selection can make a huge difference when it comes to getting the most out of seat configurations, or for making room for bikes or wheelchairs.

Space

This trend explains the increasing use of remote breaker reset (RBR) devices on passenger trains. RBRs are used to allow a train driver or other rail operative to remotely reset a circuit breaker after it has been triggered opened. Crucially, their compact size and location directly under the breaker handles frees up valuable space which is consumed by the equipment used in competing breaker technology. Worm gear reset devices, for example, are located in an extra breaker housing which occupies valuable horizontal space.

The use of RBRs can provide enough free space for the installation of two new seats on each carriage. This is of real value to train operators who, in addition to improving passenger comfort, are looking to maximise cost efficiencies.

The use of RBRs can also reduce total cost of ownership for rolling stock operators. The devices are stringently designed to meet the wide range of harsh conditions commonly found in the rail sector, and have proved to be highly resilient to the extremes of mechanical, electrical, and thermal shock. Their use can therefore contribute to a marked improvement in equipment reliability, and that in turn can help rail fleet owners to cut their costs.

So how do RBRs actually work? In terms of assembly, an RBR comprises electronics, connectors, a solenoid and piston. During normal operation, the circuit breaker is closed, allowing current to flow within the protected circuit. The handle is in the up position, and the breaker can remain in this state indefinitely. The RBR solenoid is not energised, and the piston is held in a retracted position by gravity. If a short circuit or extended overload event on the protected circuit occurs, the breaker will trip to cut the current flow, and the handle will drop into the down position.

The RBR can then be activated by a signal pulse sent from the remote-control location. This energises the solenoid, which pulls the piston upwards to strike the circuit breaker handle and reset it, allowing current to flow again in the protected circuit. As the pulse signal returns to zero, the solenoid de-energises and simply returns back to the retracted position by force of gravity.

Timing

In addition to space saving advantages, the use of RBRs also resolves timing issues related to the alternative worm gear approach, which takes several seconds to reset the circuit breaker. This can cause arcing during reset under overload or short circuit conditions, damaging contacts and eventually leading to failure. By contrast, the solenoid-based solution employed on RBRs resets breakers in milliseconds, preventing arcing damage.

Furthermore, the control circuit on the devices has been designed to draw low currents – typically around 200 mA – which avoids interfering with any associated computer systems. At the same time, a single RBR is powerful enough to reset up to four circuit breakers in the presence of a short circuit without adversely affecting the breakers’ internal components.

It’s not just the railway that is employing RBR devices. The technology is ideally suited to a wide range of other equally demanding remote environments within telecom, industrial and machinery, marine and defence applications. All RBR devices are guaranteed to provide electrical protection over time with a high level of reliability throughout conditions of shock, vibration, humidity, salinity and temperature variation.

Eaton’s RBR devices are available in three sizes and four voltage ratings, and are designed to be compatible with and mounted on to a full range of hydraulic-magnetic circuit breakers in the Eaton Heinemann series. There are several different options available to the designer in addition to the four voltage ratings (24-48-72 and 110 VDC) and three sizes. This allows rolling stock designers to find their best fit for their specific application.

Increasing application

It's clear, then, that RBRs and hydraulic-magnetic circuit breakers are going to find increasing application on the railways and in other harsh environments. In addition to their space-saving characteristics, they provide a high quality of protection while being particularly resilient to the extremes of mechanical, electrical and thermal shock. Eaton not only designs and manufactures RBR devices, but also produces the hydraulic-magnetic circuit breakers that they operate with. The company can assist with configuring or even customising integrated solutions optimised for specific applications; support is available both from their applications engineers and local distributors around the world.

To download a whitepaper entitled Space-saving benefits of remote breaker resets in rail, go to eaton.com/onboard

www.eaton.com




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