Menzel Elektromotoren has designed and manufactured three powerful 6600 V squirrel cage motors as integral components for pit fans. The customer specified cylindrical motor casings as compact as possible. The greatest challenge was to implement the required rated power of 1700 kW in cylindrical casings. Menzel therefore designed fin-cooled motors (cooling type IC 411) in frame size 630, an extremely unusual design for motors this large (Figure 1).
The manufacture is complex but the result is optimal for the constricted installation conditions. In order to save additional space, all connection cables are routed out of the motors and the terminal boxes are mounted outside the fans. Since the driven fan wheels are mounted directly on the motor shafts, the motor bearing must compensate additional high loads: radial loads up to 20700 N and axial loads up to 27000 N. For the required bearing service life of 100,000 hours, Menzel implemented a special rolling bearing setup. In addition, the motors have a second shaft end for a holding brake. The three-phase squirrel cage motors are designed for operation on a frequency converter (duty type S9) with speed changes and reversal of the rotation direction. This allows the pit fans not only to ventilate the mine, but also to extract dangerous firedamp if necessary.
Menzel Elektromotoren GmbH