Network Rail has developed a revolutionary approach to signalling projects that will save 33 % of the copper it would previously have used to distribute power. For all new projects, power for signals has been sent down three-core armoured cables, known as class 1 distribution. This includes an earth wire, along with the two live wires.
Now after three years of planning and development, a class 2 based signalling power distribution system – using two-core cable – will be deployed, with a reduction in weight, transport costs, laying costs and the cost of the cable itself. The class 2 system is now being used in the Reading resignalling scheme.
Mark Southwell, Network Rail’s IP Signalling programme director, said: “Simply put – the whole system of power transmission had to be redesigned, from the transformers to the switchgear. Normal 3-core cable has steel strands wound through it to protect it from rodent damage and other hazards – which also means that any fault will find its way to all the equipment it connects. A new form of armour had to be developed, along with double or reinforced insulation for signal housing and switchgear.
“Our engineers were also able to integrate identification features within the cable to allow it to be uniquely identified to Network Rail, helping to deter cable theft.”
Network Rail’s technical director Steve Yianni said: “Some signal projects use up to 200 tonnes of copper just in the cables, so we knew that if we could find a way of reducing that, then we could cut costs significantly, and reduce our environmental footprint. Using a class 2 signalling power system had always been thought of as impossible, or at least very difficult, but we proved it could be done. Network Rail has shown that if an engineer has a good idea, they will stand by it and deliver it too.”
To achieve this, the distribution equipment and other parts of the power system, such as switchgear and transformers, are protected with double or reinforced insulation.
For instance, a project to renew 650volt signalling feeder cables in Scotland power will need 89 km of power cable, with 267km of copper cores if it was to use traditional class 1 distribution equipment. That is a saving of 72 tonnes of copper – at £5,000 per tonne.