Operation Recommendations for Tension Joints and Clamps on a 63 kV Overhead Transmission Line Conductor Based on Experimental Tests

Abstract

This study provides the operation recommendations for the tension fittings used on a 63 kV overhead transmission line conductor based on experimental tests. In this way, the tension fittings, including the dead-end clamp, the mid-span joint, and the repair sleeve, are assembled on the lynx conductor under different faulty and healthy assembly conditions in the laboratory. The lynx conductor is one of the widely used conductors in the 63 kV overhead power lines. The electric current injection test, along with thermal imaging and also tensile test, are conducted on the studied samples. The results show that the surface temperature of the lynx conductor is higher than the surface temperatures of the dead-end clamp and mid-span joint under normal and overload current conditions. Also, the crimping pressure of the aluminum and steel pipes less than the standard value, the crimping length of the steel cores of conductor less than the standard value, and the crimping length of the aluminum pipes more than the standard value can lead to a developmental defect which should be repaired or replaced at the first opportunity of the transmission line service outage. The repair sleeve is under more thermal stress than the dead-end clamp and mid-span joint, even in the standard assembly condition. A slight temperature difference of a repair sleeve compared with the same type fitting may be a severe operating condition. Also, the use of two consecutive repair sleeves to cover the conductor cut strands is not recommended. Furthermore, the loose connection of bolts at the junction of the jumper terminal to the dead-end clamp causes a very high temperature which should be repaired immediately. If the temperature difference between two defective and healthy dead-end clamp or mid-span joint is more than 13 °C, a critical defect is diagnosed; however, the temperature difference between two repair sleeve more than 7 °C indicates a critical operation condition for defective one.

Keywords:

• overhead transmission line
• lynx conductor
• tension fittings
• operation recommendations
• experimental tests

Additional information

Notes on contributors

Jaber Dadashizadeh Samakosh

Jaber Dadashizadeh Samakosh received his B.Sc., M.Sc., and Ph.D. degrees in Electrical Power Engineering from the University of Tabriz, Tabriz, Iran, the University of Tehran, Tehran, Iran, and the Babol Noshirvani University of Technology, Babol, Iran in 2012, 2014, and 2019, respectively. His research field are high voltage engineering, high voltage equipment condition assessment, and finite element modeling.

Fardin Enayati

Fardin Enayati is a Ph.D. student in electrical power engineering at Islamic Azad University, Sari branch, Iran. He is currently the manager of the Research and equipment quality control office in Mazandaran & Golestan Reginal Electric Company. His research field are power system operation and condition monitoring.