Magnetic pulse generator for railway axle counting - has windings arranged to compensate spurious induced voltages

摘要

The pulse generator has a permanent magnet system with windings (8,9,10), soft-iron pole shoes (5,6,7) and air-gaps, with the pulses provided in response to flux variations caused by relative movement of a magnetisable object. At least two permanent magnetic circuits are used with the adjacent inner poles of the two neighbouring circuits being combined. Both the outer poles (3,4) for each circuit and the combined inner pole (2) carry a soft iron pole shoe (5,6,7) with a respective winding (8,9,10). The winding (8) for the inner pole (2) is wound in the opposite sense to those for the outer poles (3,4) so that the induced spurious voltages have opposite polarities and phase, for self-compensation.