Multiple Eddy Current Drive Overland Conveyor System with Microprocessor Control and Monitoring

Conveyors are used by some electric utilities to transport coal from strip mining operations directly to their power plants. The coal is used as fuel in their furnaces to generate steam for the steam turbines which produce the electrical energy for the public to consume. Some of these conveyors are several miles long and are made up of several individual conveyors operating as an entity. The controls for these interrelated conveyors are rather sophisticated and must function with minimum down time. Eddy current clutches-and brakes have provided the power of these conveyors for a nutmber of years and have proved very reliable. A problem in the overall system has been belt slip during acceleration/deceleration and during changes in loads. Broken belts result in extended periods of down time and must be kept to a minimum. A microprocessor has been applied to the control system not only to improve belt starting conditions but also to monitor and control the slip during running operation which will further improve belt life. It also performs monitoring functions useful in startup and maintenance procedures. The features of the microprocessor as applied to coal conveyor applications are discussed, but these are equally valid for any conveyor installation.