Transients in electric mine-winders and their effects on rope stresses

The paper sets forth the results of a number of mathematical investigations into the behaviour of electric winders during the periods of acceleration and retardation. The starting and stopping conditions both of Ward Leonard and of induction-motor-driven winders are examined with a particular view to finding out how nearly the conventional calculated speed, torque and input diagrams can be approached in practice, and the causes of departure therefrom. The possible types of acceleration and retardation that can be set up are used as a basis for examining rope stresses. Relative rope stresses are compared as between Ward Leonard and induction-motordriven winders, and as between winders working at low speeds with heavy loads and those working at high speeds with light loads. Only those starting and stopping conditions have been examined in which the variation of the controlling resistors, or currents, is an independent function of time.