Analytical Method for Coordination of Surge Arresters with Current-Limiting Fuses

Many industrial power systems have lightning exposure, requiring surge (lightning) arresters; dry-type transformers, requiring low protective levels; and high available fault currents, making the use of current-limiting fuses desirable. On occasion, current-limiting fuse arc voltages have resulted in destruction of low characteristic arresters. A traditional guideline has been to select arrester types and ratings that will not spark over on current limiting fuse maximum arc voltage¿an approach that may not be entirely viable for industrial systems. A step-by-step analytical approach to the selection of surge arresters for use with current-limiting fuses is presented. The method presumes arrester sparkover and is based on determination of system energy, fuse arc voltage and arrester back voltage characteristics, and arrester energy capability.