CHLORIDE Power Protection has developed an uninterruptable power supply for signalling that uses a 25 kV traction supply and the electricity grid to remove the need for a diesel generator back up.

Railtrack is currently reviewing the performance of a first installation, under test near Crewe on Britain’s West Coast Main Line. The UPS will accept the highly distorted AC waveform from the traction supply. This can vary between 17 kV and 27 kV as a train passes, with large spikes and transients. The UPS provides stable AC power supplies accurate to