Slip-ring motors can deliver high starting torque while drawing low starting current, and they continue to supply high torque over the entire speed range. This makes them ideal for use in the mining and cement industries, where there are many applications with high load inertia and operations are often in remote areas with weak grid conditions. High starting torque also helps to minimize mechanical stresses on the driven equipment, increasing the lifetime of the equipment and reducing maintenance needs.
Proven designs for reliability and efficiency
ABB slip-ring modular motors for the mining and cement sectors are rated up to 8,000 kW. The motors are based on proven mechanical and electrical designs and high quality materials. Features like fully braced and vacuum impregnated windings ensure reliability. Advanced ventilation technology (including radial ducts to cool the stator, and axial channels and radial ducts in the rotor) make for high efficiency. Reliability and efficiency reduce downtime and operating costs, resulting in a lower cost of ownership.
The motors’ high power density means that a smaller frame size can be used to achieve the required output. As a result these motors are more compact and weigh less than conventional designs. This makes installation easier, because less space is required and it may be possible to use lighter-duty lifting equipment at the site – factors that help to keep costs in check.
The high power density also means that while keeping the same motor frame size, the output power can be increased. This can be critical in upgrade or expansion projects where space is limited but higher output power is needed.
Separate housing for slip rings
The slip rings are enclosed in a separate housing, ensuring that carbon dust does not enter the main motor enclosure and enabling different cooling arrangements for the slip-ring unit and motor. Easy access is provided for maintenance and the brushes can be either permanent contact or liftable.
ABB slip-ring motors for mining and cement come in frame sizes 400 to 630, 4 to 12 poles. Voltage ratings are 2.3 to 13.2 kV, with both 50 and 60 Hz versions available. Ingress protection is IP55 and cooling is either totally enclosed air-to-air or totally enclosed air-to-water. The motors can be selected and configured with an easy-to-use online tool, and delivery times are short.
Slip-ring motors supplied by ABB have already proven themselves over many years powering mission-critical applications in the mining and cement industries.