Integra-Signum

Integra-Signum is a Swiss train protection system introduced in 1933. Originally it was called Signum; the name Integra was added later. It transmits data inductively and is simple, robust and reliable also in snow. How it works The locomotives have three sending and receiving magnets and there are two trackside magnets near the signals. Integra-Signum asks the train driver to confirm distant signals that show stop and distant or home signals that show caution. If he does not confirm or passes a home signal that shows stop, the train is stopped automatically. This is achieved by interrupting the power supply to the motors and applying the emergency brake. The locomotive's sending magnet is a strong permanent magnet, which induces a current in the receiving magnet in the middle of the track, if the signal's short-circuit contact is closed. The receiving magnet on the locomotive consists of two magnet field detectors, which detect the signal's state according to polarity and timing of the magnetic field emitted by the second magnet outside the track: