Investigation of disintegration and arcing in electric fuses
This thesis essentially presents the experimental investigation of the fundamental phenomena of electric fuse element disintegration and its causation and influence on the subsequent fragmentation of the fuse elements when subjected to excessive fault currents. The basis of the study involved experimental observation of disintegration of fuse elements and the analysis of the dynamic responses of current-carrying conductors, which precipitate disintegration. The experimental techniques employed utilised commercially available video cameras to capture images of element disruptions during disintegration of fuse elements subjected to low short-circuit and high overload currents. Specialist experimental image capturing techniques and hardware implementations were developed to enable investigation of element disintegration caused by high short-circuit fault currents. Disintegration phenomena of fuse elements for all fault cases were compared within different time domains, which included specialist techniques to investigate disintegration of elements in sand and against glass substrates. Disintegration phenomena of elements in unconfined media such as air and water also constituted the studies. The studies diverged, finally, into experimental observations of the temporal development of arc initiation and extinction phenomena of fault current limiting of HBC fuses using spectroscopic analysis of the arc light radiation. The range of studies covered have led to new understandings of fundamental current limiting behaviour of HBC and open type fuses which contribute, in a small way, to the knowledge base of the subject and hopefully will be an aid to improved designs and development of new types of electric fuse.