Parameter measurement of cable lead sealing using an eddy current system

Abstract

Lead sealing is one of the key accessories for high-voltage cables and its quality directly affects the security and stability of such cables. In order to reduce the accident rate in power processing caused by lead sealing issues, it is necessary to carry out non-destructive testing and evaluation. Due to the bending surface of lead sealings, it is difficult to detect their conductivity and thickness accurately using existing eddy current (EC) testing methods. In this paper, measurements of conductivity and thickness for curved specimens are analysed and an accurate method is subsequently proposed. Firstly, the measurement methods of conductivity and thickness are established based on the transformer model. It is found that the conductivity and thickness can be detected using phase signature at high and low frequencies, respectively. Secondly, the influence of curvature on the phase signature is analysed and the conductivity and thickness measurements of lead sealing are corrected using curvature correction coefficients. Finally, an EC system is built and experiments are carried out to evaluate the novel methods. The results show that the methods achieve a good level of accuracy in detecting the conductivity and thickness of curved lead sealings.