Signalling Equipment

Automatic Power Control Magnet

Automatic Power Control Magnets are used to instruct an electric locomotive to open the circuit breaker on its transformer, so it does not draw current as the pantograph traverses a neutral section, to eliminate arcing.

A second magnet tells it to switch back on again afterwards. It is mounted on the end of a sleeper to align with the trainborne sensor. Using a simple spacer, the magnetic properties can be checked with either a standard Strength & Polarity meter or a Gauss meter.


Technical Features

  • A highly stable magnetic field is created through the use of rare-earth magnets
  • The APC magnets attach to one sleeper only, irrespective of fastener type
  • Compatible with any standard concrete or timber sleepers
  • Lightweight assembly
  • Can be installed into switch and crossing sites


  • Typical cost savings of £3,000 to £4,000 per location
  • Quick and easy installation in 2-3 minutes
  • Minimal maintenance required – does not degrade over time, regardless of temperature, operating cycles or shock
  • Low profile reduces risk of being struck
  • Does not need to be removed for tamping operations
Signalling Equipment

Automatic Power Control Magnet