An angular pulse generator which is used in speed sensors, based on phonic wheel or turning cable technologies, is installed inside the ERCU box and transmits information to an electronic system to: - Detect whether the train is running or stopped, in order to trip or release safety systems such as door locks - Measure the speed of the train - Detect which way the train is traveling - Detect when a train is braking, with possibilities of skidding/sliding/locking of individual axle. In these cases adhesion between the rails & wheels is crucial. Above situations can cause damage to wheel sets with increased braking distance. The Speed sensor will detect the speed of the wheel and inform the Wheel Slide Protection System which main purpose is to optimize the available adhesion. Mersen innovate in adapting two different speed sensor technologies in our Earth Return Current Units range. First one is based on a non-contact sensor counting of RPM of a phonic wheel, the second speed sensor technology is based on a cable connected to junction box. These 2 in 1 solutions bring you many advantages (compactness, weigth, cost) and they are based on two proven technologies in railway applications. Some references : Railway : MAYNILA (PH)