WEG’s new M Mining series of slip-ring motors are designed for use in the mining and cement industries. Their high performances, robustness, electromechanical properties and high IP rating make them withstand the harsh, dusty environments of these sectors.
by Andrea Baty
WEG, a manufacturer of motors and drive technology, presents the new M (Mining) series of slip ring motors for use in the mining and cement industries. Available in frame sizes IEC 355 to IEC 1000, the new M Mining slip ring motors cover the power range from 250 kW to 10 MW at 50 Hz or 60 Hz line frequency. These three-phase induction motors between 4 and 14 poles and are designed for voltages up to 13.8 kV. The robust M Mining series is intended for dusty environments in the iron ore or cement sectors. This makes the slip-ring motors a reliable choice for mills, crushers, blowers, exhaust fans, conveyors, centrifuges, and other applications in the mining and cement industries.
These motors combine performance and robustness with a high IP rating, steel casing and two different brush systems.
The design is based on specific electromechanical properties that offer long life and high stability.
High starting torques along with a low start-up current
The wound rotors of slip ring motors allow them to achieve high starting torques along with low start-up current. In contrast to squirrel-cage motors, the windings are connected to three slip rings that allow a variable resistance to be inserted in the rotor circuit. This has several major benefits for users including: higher rotor circuit resistance which allows the motor’s start-up characteristics to be improved; the motor starting current is kept virtually the same as the rated current; and loads with high starting torque can be driven, as well as loads with high inertia. Further advantages include higher efficiency and simple installation.
The new motor series has a brush compartment with a completely new design and a transparent window for inspection and access. Commissioning is simplified by combining the motor with a fully integrated control panel as an option. At the same time, operating and maintenance costs are reduced and plant availability is increased.
Choice of two different brush systems
The motor series is available in two versions: either with a brush lifting device, or with brushes in constant contact. The lifting mechanism of the brush lifting device has been redesigned to make it even easier to maintain. Compared to the version with fixed brushes, the brush lifting system requires less maintenance. In addition, brush wear is reduced by fitted pressure springs. An integrated control system is also available as an option for the brush lifting device.
With its innovative design and new insulation arrangement, the system offers alternative advantages. For example, the cooling system of the brush compartment is independent of the motor cooling system, further boosting the efficiency. The extended lifetime of the brushes is one of the main advantages, but user access to the brush compartment is also significantly easier with this version. The brush compartment achieves an IP rating of up to IP66.
The M Mining motors are available with protection ratings from IP55 to IP66. They are also protected by WEG paint systems that enable operation in abrasive and humid environments with atmospheric sulphur dioxide.