Thomas J. Schoepf

Characteristics of Overheated Electrical Joints Due to Loose Connection

Abstract - Overheated electrical joints due to loose connection are often precursors of electric fires, arc faults, and arc flash in electrical systems. This paper is about the formation mechanism and behavior characteristics of loose connection induced overheated electrical joints. Specific experiments were conducted on busbar joints and systems with currents ranging from 100 A up to 5000 A. The lead time of the overheated contact formation is significantly impacted by the tightening torque of busbar bolts, the amplitude of current, and the proper sizing of electrical joints.

Application Feasibility of Detecting Glowing Contacts Using Acoustic Sensing Technology

Glowing contacts may be precursors to arc faults and could lead to fire hazards even before arc faults occur. As of today there is no cost effective technology available to detect overheated or glowing contacts. Experiments have been conducted in order to investigate both the acoustic characteristics associated with glowing contacts and the feasibility of their detection under various conditions by employing acoustic sensing technology. Experimental results show that the propagation or attenuation of the acoustic signal through electrical circuits is significantly influenced by size and length of electric wires and types of electric connections. The results also further demonstrate that the acoustic signal can propagate effectively through large cable conductors and busbars, hence enable glowing contacts detection for industrial applications. However, the attenuation of acoustic signal through electrical circuit could be a potential limitation for residential applications.