Loose fuse caps impact reliability

Improper installation of fuses in cutouts can result in unplanned outages, some at the feeder level. Whenever installing fuses in fuse cutout fuse tubes, the supplier´s instructions should be followed. Key among these is the proper torque on the cap of the fuse tube. Loose caps result in heating. This heating acts as a preload and causes faster fuse clearing than TCC´s indicate. This results in unexplained outages on branch lines, and in the case of capacitor banks can result in feeder level outages. This paper shows results of investigations and testing to determine the causes of unplanned fuse outages.