Detection and formation process of overheated electrical joints due to faulty connections

Overheated electrical joints due to faulty connections are often precursors of electric fires, arc faults and arc flash in electrical systems. NEMA procedures call for visual inspection and re-torque on a regular base. Various technologies have been developed for the detection and mitigation of overheated connections. As of today there is no cost effective technology available to monitor and detect overheated electrical joints in electrical distribution equipment. This paper reviews different technologies developed to monitor and detect overheated electrical connections. Results of recent feasibility investigation on overheated connection detection employing acoustic sensing technology are introduced. Furthermore, investigations on the formation mechanism and behavior characteristics of faulty connection induced overheated electrical joints at different current levels are discussed. The results demonstrate that overcurrent has a major impact on the overheated electrical joint formation process. Collapsing of overheated contact spots can be observed during the thermal test cycle. It is an indication of softening or even melting of the existing contact spot and formation of a new contact spot.