OVERLOAD PROTECTION

摘要

Method and device for indicating overload already when the lifting starts of a load suspended in a rope. The hoist comprises a slip-ring induction motor (1). The input power together with the angular velocity of the rotary movement are metered. Then the metered values are compiled in a computer (5) by means of a suggested formula in order to estimate the hook load. The lift will be stopped, if the hook load continuously exceeds a predetermined value during a predetermined time.