Conveyor belt monitoring

A system for monitoring operation of a conveyor belt installation which comprises a conveyor belt having steel or other relatively magnetically permeable reinforcing material, said system comprising:

• a field generator arranged in proximity to the conveyor belt to generate a magnetic field;
• a sensor unit arranged in proximity to the conveyor belt at a position downstream from the field generator as considered in a normal direction of belt movement, said sensor unit sensing the magnetic field emanating from the passing conveyor belt;
• and
• monitoring unit to receive data related to the magnetic field properties sensed by the sensor unit during a plurality of passages of each part of the length of the conveyor belt past the sensor unit, said monitoring unit incorporating a comparison unit to compare a subsequently received set of data with an earlier received set of data, and an output unit to provide an output signal representative of reinforcement damage or deterioration when subsequently received
• data has departed from earlier received data by more than a prescribed extent,
• wherein the monitoring unit comprises a data store to store data related to conveyor belt properties as detected either at the time of initial installation or following a maintenance or repair operation of a conveyor belt, and
• a selective override facility is provided and operable, following one of a localized belt repair and maintenance operation, to update stored information solely in respect of properties of the part of the length of conveyor belt that has been the subject of one of the localized belt repair and maintenance operation but retain the originally or earlier stored data in respect of the remainder of the length of the conveyor belt.