Method and apparatus for controlling release of hoisting motor brake in hoisting apparatus

摘要

A method and an apparatus for controlling release of a hoisting motor brake in a hoisting apparatus (1), where electricity is used as the driving force and a squirrel cage motor as the hoisting motor (2) for hoisting or lowering a load (7) attached to a hoisting member (5) of the hoisting apparatus (1). Controlling of brake release comprises measuring the current and supply voltage of the hoisting motor (2) after the start-up period of the hoisting motor (2) and determining a variable which describes the load of the hoisting apparatus (1) from the current and supply voltage. The variable describing the load is compared with a pre-determined limit value and hoisting or lowering of the load (7) is interrupted if the variable describing the hoisting apparatus load exceeds the limit value set for the hoisting movement when the load (7) is hoisted or if it exceeds the limit value set for the lowering movement when the load (7) is lowered.