Distribution fuse links: Responsible for the damage of equipment at substations !!!

摘要

The main objective of this project is to present the result of studies and tests done on field and in laboratories, with real short circuits, with the purpose of improving the quality of distribution fuse links, specially the ones used to protect distribution transformers (15 kVA, 45 kVA, 75kVA, 225 kVA, etc), “H” types, in the classes of tensions of 13.8 kV and 34.5 kV. These protection devices, due to their low quality, were causing several kinds of problems at the distribution circuits, and also at the equipment installed at the Substations. At the distribution circuits, the main problems that occur are that, defects caused at the low-tension circuits (127/220 Volts), such as colliding cables, tree branches at the network, collisions, storms, etc, were causing bi-phased or three-phased short circuits at the feeder circuits of 13.8 kV and 34.5 kV that come from the Substations. These defects cause, many times, the touching of conductors at the side of High Tension, which is detected by the protection equipment installed at the Substations, work done by Re-closer or Circuit Breakers with over current relays.