The requirement for individual fusing to avoid a case rupture in event of a failed capacitor unit was developed as a standardized protection practice for the earlier capacitor units with kraft paper as dielectric material. Today, the use of polypropylene film dielectric in capacitor units minimizes the incidence of rupturing in the event of an internal failure. A capacitor bank using external fuses usually requires a number of parallel units in each series group so that the operation of one fuse does not result in excessive voltages across the remaining units. This requirement often results in using many smaller kVAR units to achieve the designed capacity. With the fuseless bank, the failure of one element results in very little increase in voltage on the remaining elements in that string. This enhanced design often results in a substantially reduced number of units, using larger kVAR units to achieve the same total capacity.
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