Ideal for the mining industry

WEG is presenting 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 have 4 to 14 poles and are designed for voltages up to 13.8 kV.

(C) Koenig

The robust M Mining series is intended for dusty environments in the iron ore or cement sector. 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.

Robust motor, high performance
“Their performance and robustness make the new M Mining series of motors, with their high IP rating, steel casing and two different brush systems, an excellent choice for applications in the mining and cement industries", comments Andreas Schulte Mesum, Director European High Voltage Solutions at WEG Germany GmbH. “The design is based on specific electromechanical properties that offer long life and high stability.”

High starting torques
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 benefits for users: Higher rotor circuit resistance allows the motor's start-up characteristics to be improved. The motor starting current is kept virtually the same as the rated current. In addition, 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. Simplified commissioning is possible by combining the motor with an optionally fully integrated control panel accessory. At the same time, operating and maintenance costs are reduced and plant availability is increased.

In the M Mining slip ring motor version with liftable brushes (left), the brush lifting mechanism has been simplified to make maintenance easier. Brush wear is reduced by fitted pressure springs. In the M Mining slip ring motor version with fixed brushes (right), the cooling system of the brush compartment is independent of the motor cooling system, leading to higher efficiency.

Choice of two different brush systems
The motor series is available in two versions: either with a brush lifter or with brushes in constant contact. Each version has its specific advantages in individual use cases. 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 scores with lower maintenance expenditure.  In addition, brush wear is reduced by fitted pressure springs. An integrated control system is optionally available for the brush lifter.
The system with the brushes in constant-contact, with its innovative design and new insulation arrangement, offers different 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. User access to the brush compartment is also significantly easier with this version. An IP rating up to IP66 is possible for the brush compartment.

The M Mining motors are available with protection ratings from IP55 to IP66. They are additionally protected by WEG paint systems that enable operation in abrasive and humid environments with sulphur dioxide content in the air.