The gearbox is an integral part of the drive system; if it fails, the system will be down for a considerable time. For this reason, low-speed gearless conveyor drives
(GCD) are increasingly becoming the solution of choice for mining projects – particularly those that require high drive power. GCDs enable and help to boost the efficiency of high-capacity belt systems, while reducing energy usage, downtime and maintenance.
Gearboxes that are able to handle powers in excess of 3.5MW are maintenance-intensive and their productive lifetime is relatively short. ABB has addressed this issue by replacing the gearbox with robust, reliable control from variable speed drives running accurately performing, low-speed motors.
In this set-up, permanent magnet motors can produce the same torque power with 20–25% less motor current, thus reducing the size of frequency converters and motor feed cables. Because of their compactness they reach similar sizes as geared drives and so can replace them. Also, the number of motors needed on the drive system by combining the power demand in one permanent magnet motor can be reduced, resulting in less maintenance and energy consumption.