RSSB2711 - T1150 - A feasibility study into the use of High Voltage couplers on rolling stock

Optimising the performance and reliability of existing and new electrification/pantograph systems remains a key focus for the rail industry.

In recent years to increase capacity the use of electric multiple units formed of up to 3 units (for example a 12-car train formation) has become more widespread .

At the same time opportunities have been taken to increase the speeds of services to fully utilise the capabilities of modern rolling stock, reduce journey times and essentially keep up with high speed services.

It is understood that several Overhead Line Equipment (OLE) systems in GB were designed for single pantograph compatibility but have been progressively shown to be compatible with two and three pantograph operations with some constraints.

The use of multiple pantographs is potentially sub optimal and perhaps limits the train maximum speed due to multiple pantograph/contact wire performance.

One of the potential methods of avoiding the need to use two or three pantographs per train is to use high voltage (HV) couplers distributing energy between the multiple units.

Whilst this does not reduce the cost of directly introducing electrification, as is discussed below, there are other benefits that this could bring to the network.

There has been some preliminary experimentation in controlled climatic conditions, where the capabilities of a HV coupler design for railway use has been proven, with the findings patented.

High voltage couplers are also used in other industries such as mining and there are a number of proprietary designs available but probably intended for different applications.

The case for using HV couplers has so far not been fully investigated and this project through a thorough desk-based feasibility study will provide a report on the potential application and use of the technology.

At the November 2017 Pantograph to OLE working group meeting it was recognised that the DfT aspire to operate multiple units, with up to three pantographs raised.

However, on some routes with legacy OLE infrastructure the potential maximum speed is limited which means the potential path might not be available or the train has to run with only two units.

This is due to the disturbance from each pantograph on the contact wire and resulting in each following pantograph needing to track a moving wire.

At higher speeds, and shorter pantograph spacing, there is less time for the contact wire to stabilise between pantographs.

This study is split into three separate chains of feasibility analysis: 1.

Operation and performance 2.

Safety 3.

Economic Most importantly, this study will analyse the operational feasibility of using a HV coupler.

Considerations for the operation of the HV coupler will need to consider the reliability of the technology to withstand frequent connection and disconnection in line with carriage(s) usage across timetables.

The study will need to consider differences in rolling stock design for physical placement of the cables