Eversholt scopes out re-traction upgrades

Source: Rail Technology Magazine Dec/Jan 2013

RTM speaks to Richard Carrington, Eversholt Rail Group’s head of projects and procurement, and Vossloh Kiepe UK’s principal consultant Karl Barras about the potential for a traction system upgrade on Eversholt’s fl eet of Class 321 and 322 electric multiple units.

Eversholt Rail Group has taken the fi rst steps towards an upgrade that will enable its large Class 321/322 fl eet to operate effi ciently until 2032, signifi cantly reduce maintenance costs and provide energy savings.

The traction upgrade will include the replacement of the present WSP system with the Knorr-Bremse EP98 brake control system. This will provide a modern brake blending system between the friction brake and Vossloh Kiepe traction system electric brake, which will return regenerating energy back into the overhead line, promising energy savings of around 17%.

With this goal in mind, the contract for a Feasibility Study was awarded to Vossloh Kiepe UK, formerly Transys Projects, in August 2012, for completion by March 2013. Richard Carrington, Eversholt Rail’s head of projects and procurement explained how important it was to investigate every reasonable opportunity to future-proof the fl eet, saying: “We’re pleased to have this opportunity to understand the feasibility of providing a new traction system for the Class 321, working with Vossloh Kiepe UK to develop a new modifi cation. This will enable us to offer up-to-date rolling stock to our customers.”

The project encompasses all traction equipment design, installation design, procurement and installation of the Traction System Upgrade on Eversholt Rail Group’s Class 321 fl eet, as well as providing full certifi cation and a Safety Case for the new traction, auxiliary power and braking control systems. The aim is to take the design, safety case and associated processes to a ‘preconcept’ stage. This will enable a full evaluation of the new traction system, the installation design and certifi cation as well as providing accurate pricing for the placement of a contract for the re-traction of a pre-production Class 321 and subsequently, fleet modification.

Vossloh Kiepe UK’s principal consultant Karl Barras added: “We’ve been asked to consider all major aspects of the new equipment, installation, operational issues, reliability and maintenance, safety engineering, energy and cost savings for the integration of modern technology into the existing Class 321 units prior to the upgrade of the fleet.”

The upgrade will include the replacement of the present DC traction system with the Vossloh Kiepe modern 3-phase AC IGBT-based, liquidcooled traction system. The new equipment will be contained in a single case, using the same mounting interfaces as the present traction case, and will be designed to be contained within the profi le of the present case.

The present DC traction motors will be replaced with lighter 3 phase AC traction motors arranged to use the same mounting interfaces with the bogie frame and axle suspension tube.

The existing axle mounted gear wheel and final drive casing will be used, with the existing pinion fitted to the new AC motor shaft. The gear ratio will be the same as the existing final drive.

The decision was taken to replace the existing main transformer with a modern transformer, using the same mounting positions as the existing transformer.

Barras added: “We had to consider safety case reasons, the integrity of the existing transformer when subjected to regenerative energy and its suitability to operate with the new traction system.”

The present HT cable will be replaced with a modern cable, gland and plug assembly. Additional current and voltage monitoring devices and a new type of VCB will also be incorporated into the traction supply system.

Both Barras and Carrington acknowledged that the present WSP system is unreliable and suffers with obsolescence issues. As a result, a modern WSP system incorporated with the Knorr-Bremse EP98 brake control system will replace the present brake control and WSP system on all four vehicles in a unit. This will provide traction/friction brake blending throughout the unit and enable maximum regeneration of braking energy to maximise energy savings, brake pad and disc replacement costs. Preliminary investigations show that reductions of up to 17% energy costs, 50% brake pad costs and 80% brake disc costs can be realised. In addition, the replacement WSP system will reduce wheel flats and reduce wheel turning costs by up to 90% of the present Class 321 units.

Carrington said: “The Knorr-Bremse EP98/ WSP system was selected because of their experience with modern UK EMUs, and five Class 321 units have already been fitted with the Knorr-Bremse WSP system for evaluation purposes. We are working with both Knorr- Bremse and Vossloh Kiepe to optimise the blending scheme and now the potential savings for energy and maintenance is very significant.”

A new auxiliary supply system and associated increased battery capacity will be provided to supply power for the HVAC provided by other contractors and to meet the enhanced emergency ventilation requirements. Due to the increased supply requirement of these systems and the restricted nature of the motor car vehicle, the new auxiliary converter and battery box will be located on one of the driving trailer cars.

One of the major challenges the team face on this project is the integration of modern traction and braking systems into an existing unit with the minimum of mechanical and electrical disruption to the existing vehicle systems and infrastructure. This will be important to minimise both installation and operating costs for the upgraded units.

Both Carrington and Barras agreed that effective communication will be vital in ensuring the deadline is met and the feasibility study is successful. Barras explained: “We are in constant dialogue with Eversholt Rail Group and our safety engineering partners Lloyds Register Rail, as well as Knorr-Bremse and our colleagues at Vossloh Kiepe in Germany.

“Between Vossloh Kiepe in Germany and the UK we have up to 10 experienced engineers working on the Feasibility Study, who will also be involved on the pre-production and fleet fit phases.”

This collaborative approach has been welcomed by Eversholt Rail Group, according to Carrington, who said: “We have a strong team of specialists and highly experienced engineers from a number of companies on this project, all working towards a common goal. We’re very excited about the direction this study is taking and the opportunities it has revealed.”

Tell us what you think – have your say below, or email us directly at


DW Down Under   25/03/2013 at 08:34

Would the traction renewal design be also applicable to earlier MkIII based EMU designs, such as Class 317, 318, 319? Indeed, how valid would such a retrofit be to the PEP based classes 313, 314, 315, 507, 508? DW down under

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