Sectionalizing and Internal Transformer Fusing on Rural Power Circuits

This paper discusses the co-ordination of internal transformer fuse links with line sectionalizing devices on 7.2/12.5-kv multigrounded neutral rural lines, and methods for improving this co-ordination and the electric service to farm areas. An internally mounted primary fuse link is an integral part of the transformer on a large number of the transformers supplied to rural electric systems. In the interests of more adequate sectionalizing and less interrupted power aimed toward the improvement of electrical service to the farm consumer the following suggestions are made: 1. Internal links of various transformer manufacturers should be standardized. 2. The rating of the link in the conventional internally-fused-type transformer should be no greater than that in the entirely self-protecting type of the same rating. 3. The characteristics of the internal link should be designed for better co-ordination. 4. The characteristics of sectionalizing reclosers should be designed for better co-ordination. 5. System studies should give consideration to proper co-ordination of reclosers and transformer protective equipment.