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Monitoring the current in railway lines to check signalling currents

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At a glance


UK / India / Brazil



The Challenge

Currents of a few amps in the range 1 - 2 kHz are an essential part of the railway signalling system for determining where the trains are. When there is a fault the trains cannot run and it is important to find the fault with a minimum of delay.

Provide a current transducer to measure signalling currents in a railway line that can be moved around easily to trace the currents.

Our Solution

A U-shaped Rogowski coil was developed which could be simply dropped over the rail to make a measurement. This was a battery-powered unit and the integrator incorporated a high-pass filter that would allow measurement of the higher-frequency signalling currents but reject 50Hz signals which could cause interference.

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