Discussion on “electrical control of a large mine hoist” (Cheney), Pittsburgh, Pa., April 27, 1912. (see proceedings for March, 1912. (continued from November, 1912, proceedings, page 2060)

Answering the criticism of the high slip (and consequent low efficiency) at full speed, Mr. Cheney stated that where the period of full speed running is long it will be advantageous to short-circuit the motor secondary at the brushes by means of switches. It is extremely doubtful whether any simple and wholly reliable method can be obtained whereby contactors (or other forms of switches) can be used to short-circuit the rheostat automatically when the liquid rises to its maximum level.