TABLE OF CONTENTS

Introduction Conventional magnetic-inductive wire cable test Radiographic testing Imaging method Comparison of test duration Summary

Summary

Magnetic inductive testing of cables is designed to ensure safety of aerial cableways by detecting wire fractures caused by wear and corrosion to carrying, traction and hoisting cables. The difference between indications of fractures and corrosion of the wires is often difficult to detect when the cable is fully sealed and it is seldom achieved with absolute certainty. The evaluation is subjective and requires considerable experience. Usually the decision as to whether a cable can continue in service is decided on the basis of radiography images. This a rather costly procedure and not without problems because of safety requirements (handling of strong radioactive sources) and due to the exposed working conditions with aerial cableways. This test method therefore demand teams that are well trained and well equipped.

Up till now the measurement of the scatter field produced by damage in a cable has been carried out either cumulatively around the complete circumference of the cable, either split into two 180° sectors or into 4 overlapping 180° sectors. Nowadays the detailed measurement of the magnetic scatter field of a wire cable, divided it into 24 to 60 sectors, depending on the diameter, is made possible by using the Hall effect in semiconductors combined with the increasing processing capacity of a personal computer. The image of the high resolution magnetic scatter field and the wide range of data processing facilities provide a new basis for decision making.

In the following sections the two previously used test procedures are described and this new imaging method is introduced.