Method and arrangement for measuring load of hoisting apparatus
AssigneeKCI Konecranes International PLC
InventorAri Kiviniitty
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Abstract
A method and an apparatus for measuring a load of a hoisting apparatus, where electricity is used as the driving force and a squirrel cage motor as the hoisting motor for moving a load attached to a hoisting member of the hoisting apparatus substantially in the vertical direction. The method and arrangement are employed to determine air gap torque of the hoisting motor, which describes the load of the hoisting apparatus, utilizing magnetization flux of the hoisting motor determined on the basis of the current, supply voltage and stator winding resistance of the hoisting motor. The value of the air gap torque is compared with an air gap torque curve determined for the hoisting apparatus at known reference loads to determine the load that corresponds to the air gap torque in question.
Claims19
A method of measuring a load of a hoisting apparatus, where electricity is used as the driving force and a squirrel motor as the hoisting motor for moving a load attached to a hoisting member of the hoisting apparatus substantially in the vertical direction, the method comprising measuring the current and supply voltage of the hoisting motor, determining the stator winding resistance of the hoisting motor, determining air gap torque of the hoisting motor, which describes the load of the hoisting apparatus, utilizing magnetization flux of the hoisting motor determined on the basis of the current, supply voltage and stator winding resistance of the hoisting motor and comparing the air gap torque with an air gap torque curve determined for the hoisting apparatus at known reference loads to determine the load that corresponds to the air gap torque in question.
An apparatus for measuring the load of a hoisting apparatus, where electricity is used as the driving force and a squirrel motor as the hoisting motor for moving a load attached to a hoisting member of the hoisting apparatus substantially in the vertical direction, the apparatus comprising means for measuring the current and supply voltage of the hoisting motor, a measuring member for measuring a variable describing the stator winding resistance of the hoisting motor, and a load measuring device for determining magnetization flux of the hoisting motor on the basis of the current, the supply voltage and a variable describing the stator winding resistance of the hoisting motor and for determining air gap torque of the hoisting motor, which describes the load, on the basis of the magnetization flux, the load measuring device comprising means for comparing the air gap torque with an air gap torque curve determined for the hoisting apparatus at known reference loads to determine the load that corresponds to the air gap torque in question.
Dependencies are inferred from the claim text.