Wire Rope Fault Detection in a Hoisting Winch System by Motor Torque and Current Signature Analysis

The aim of this paper is to analyze theoretically and experimentally the stator current and load torque of a three-phase induction machine in a hoisting winch system. This is performed in order to show how these variables are influenced by the wire rope faulty conditions. When the wire rope is subject to axial and torsional loads, the outer strands can be separated from the core in a permanent way and make the rope less reliable. The term “birdcaging” is used to describe this type of phenomenon by giving a permanent appearance of a wire rope forced into compression. In a hoisting winch system, the rope is bent over a drum and a pulley, and it is torsionally stressed by the fleet angle between them. In this paper, the effect of the fleet angle is observed in the stator current and the load torque in order to detect the “birdcaging” effect. This study is performed on a 22-kW three-phase squirrel-cage induction machine driving a reduced scale winch system, and it presents an original noninvasive way to detect a wire rope fault condition.