Innovative off-load switching

With the increase in electrification activities around the country, various new techniques and equipment are being trialled or are coming online to both make installation easier and to make operation more efficient.

Network Rail is therefore working with its supply chain to develop new technology as the suppliers have the specialist knowledge that will make these new initiatives work.

One good example is a new type of load-break switch which can be operated with the associated circuit breakers closed and the line live. The switch may be opened or closed with load from trains drawing current without damage to the isolator.

Developing the LB1250

Since Network Rail announced the requirement for such a device, Morris Line Engineering (MLE) has been in discussion with various key stakeholders. With existing offerings being either off-load only or requiring two switches to handle switching and earthing, it was obvious that an on-load version of its D1250 isolator would be very useful. Having met with a number of decision makers, both from central Network Rail and the major electrification projects, all input was taken into account in the product development phase, culminating in the creation of prototypes in 2014.

MLE has now been supplying the UK railways with high quality isolators for more than 35 years, with a strong record for robust, reliable systems. Throughout the winter, the company carried out a variety of in-house tests confirming the new unit’s functionality and endurance performance. Having satisfied such requirements, a full range of high-voltage tests of the vacuum break head (in situ on the switch) was carried out at a testing station in the Netherlands. After the best part of 18 months in development, there was considerable anticipation for the result and satisfaction all round when the new unit passed with flying colours.

The LB1250 switch utilises the same key components as the existing D1250 isolator which has been in service for several years. Indeed, off-load switches already in service can be upgraded to load break units by changing just a handful of parts.

As with the D1250, the LB1250 comes in twenty different configurations to suit every application. It is offered in single or double pole, with or without earthing, and with the option to fit micro-switches in order to deliver electronic indication of the isolator blade’s position. The operating mechanisms remain in common with the D1250 and reflect Morris Line’s ‘belt and braces’ philosophy to building solutions able to cope with variable operating conditions and long life spans.

The vacuum head is a tried and trusted product, sourced from an established manufacturer and rated to 10,000 operations. MLE has designed the housing and its operating mechanism to integrate this unit into its existing arrangements and these will continue to be produced in the company’s Bridgend factory to its usual high quality standards.

Designed and built in the UK

The South Wales manufacturing facility was enlarged in 2013 and produces a wide range of products, including track switches and “FED” fixed earthing devices which are supplied to the rail industry. Working closely in collaboration with Network Rail, MLE is focused on being ready for the challenges ahead.

Manufacturing director Brian Jones commented: “After a slow start to rail electrification in the UK, things have changed over the last five years and we have been actively listening to what the rail industry’s new drivers are, so that we can work to meet those needs. The LB1250 represents a significant step in offering a wider range of solutions and meeting new technical challenges.

“As a British manufacturer and supplier to Network Rail, we aim to excel through highly integrated design, quality focused manufacturing and robust system components.

We look forward to supplying the first units of our load break switch over the coming months.”

MLE is part of the Morris McClellan Group which has a turnover in excess of £45 million and employs over 350 staff. In addition to its high voltage isolation and earthing equipment, the company also manufactures low voltage switchgear products suitable for rail applications. With electrification activity now heavily accelerating, it’s understandable they are excited at the prospects.