Citation: Liao, C.; Yi, Y.; Chen, T.; Cai,
C.; Deng, Z.; Song, X.; Lv, C.
Detecting Broken Strands in
Transmission Lines Based on Pulsed
Eddy Current. Metals 2022, 12, 1014.
https://doi.org/10.3390/met12061014
Academic Editors: Alberto
Campagnolo and Alberto Sapora
Received: 16 May 2022
Accepted: 13 June 2022
Published: 15 June 2022
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Article
Detecting Broken Strands in Transmission Lines Based on
Pulsed Eddy Current
Chunhui Liao
1,
*, Yinghu Yi
1
, Tao Chen
1
, Chen Cai
2
, Zhiyang Deng
1
, Xiaochun Song
1
and Cheng Lv
3
1
Hubei Key Laboratory of Modern Manufacturing Quantity Engineering, School of Mechanical Engineering,
Hubei University of Technology, Wuhan 430068, China; 101910105@hbut.edu.cn (Y.Y.);
chentao@hnu.edu.cn (T.C.); dzy@hust.edu.cn (Z.D.); songxc@mail.hbut.edu.cn (X.S.)
2
Wuhan Second Ship Design and Research Institute, Wuhan 430064, China; 20160069@hbut.edu.cn
3
Hubei Special Equipment Inspection Testing Institute, Wuhan 430068, China; chenlv_nick@163.com
* Correspondence: cloudy_c119@163.com
Abstract:
High-voltage transmission lines are the main facilities for power transmission, and they
are mainly composed of aluminum conductor steel-reinforced (ACSR). Over long-term outdoor use,
overhead transmission lines will encounter lightning strikes, chemical pollutant corrosion, deicing,
wind vibration, and other external forces. This often results in a series of potential failures, such as
breakage, for the strands. In order to ensure the safe operation of the power grid and avoid fatal
accidents, such as line breaks, it is necessary to identify and repair line faults. Among them, the
main basis for the regular detection and replacement of high-voltage transmission lines is whether a
broken strand defect appears. In this paper, a type of pulsed eddy current (PEC) sensor is developed
to detect the broken strand defect in transmission lines. The simulation and experimental results
showed that the designed PEC sensor could effectively and accurately identify the fault.
Keywords: transmission line; broken strands; pulsed eddy current testing
1. Introduction
Pulsed eddy current is a novel method for eddy current testing (ECT). The square
wave excitation used in PEC can be regarded as multiple-frequency components after
Fourier decomposition. PEC nondestructive testing techniques can overcome the skin effect
on ECT within a certain range. Therefore, compared with single-frequency ECT techniques,
PEC exhibits a greater penetration depth, and exhibits extensive applications in airplane
multilayer structure detection and pipeline inspection in the petrochemical and power
industries [1].
Power transmission lines are the preliminary and key facilities for power transmission,
which are mainly composed of aluminum strands on the outer layer and steel strands for
support. Over long-term outdoor service, overhead transmission lines may be destroyed
by lightning, corrosion by chemical pollutants, ice shedding, wind-induced vibration of
the conductor wires, line dance, external damages, etc. [
2
–
5
]. Some fatal accidents, such
as line breakage, may be triggered if the failures cannot be recognized and repaired in
time, thereby imposing serious effects on the power quality and transmission ability. In
order to ensure safe operation of the power system, it is necessary to undertake periodic
inspection of power transmission lines. Currently, workers mostly use telescopes to inspect
potential failures along high-voltage and ultrahigh-voltage power transmission lines that
require high labor intensity and low precision. Maintenance in the air with helicopters is a
high-cost and fairly dangerous issue [6].
A great deal of research has been carried out on the inspection of power transmission
lines, for instance, the development of robots with imaging sensors for inspection [
7
–
9
].
Using these robots, the breakage of externally stranded aluminum wires can be directly
detected. However, the inspection robots are only applicable to defects on the outer surface
Metals 2022, 12, 1014. https://doi.org/10.3390/met12061014 https://www.mdpi.com/journal/metals
