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.