Braking controller for roller-cutter in mining operation - imposes limit on frequency of supply from inverter to traction motors until brake release is signalled e.g. by proximity sensors

摘要

The cutter (1) with its two rollers (2, 3) is held esp. on steep inclines by special brakes (8, 9) acting on the traction motors (6, 7) whose supply current frequency is measured independently of the invertor (33). The latter is run-up initially to a min. frequency of e.g. about half of the nominal slip frequency of the three-phase induction motors. Further increase in frequency is possible only when a signal to the controller (28) indicates that the brakes are off. ADVANTAGE - Device guarantees freedom from malfunction of brakes in event of disturbances in transmission of data from cutter.