Enhanced sectionalizing through proper testing of recloser time current curves

The recent proliferation of software packages containing computer generated time-current curves have helped to free distribution engineers from curve-tracing using transparencies on electric light tables. The new software packages offer speed, flexibility, and ease of operation that enable the distribution engineer to provide enhanced sectionalizing for radial distribution systems. Single phase hydraulic oil circuit reclosers usually comprise a large portion of rural distribution systems and hence, represent a huge percentage of the total sectionalizing scheme. Unfortunately rebuilt oil circuit reclosers do not always exhibit time-current characteristics as depicted on computer generated or manual light tables. This paper summarizes considerations for proper recloser-recloser and recloser-fuse coordination. The paper also presents an approach and method of testing time-current characteristics of single phase hydraulic reclosers with oil or vacuum interrupters. Computer light table software is used to confirm if the “as-tested” time-current characteristics fall within specified tolerance limits