Single Phase Earth Faults in High Impedance Grounded Networks Characteristics, Indication and Location.

摘要

The subject of this thesis is the single phase earth fault in medium voltage distribution networks that are high impedance grounded. Networks are normally radially operated by partially meshed. First, the basic properties of high impedance grounded networks are discussed. Following this, the characteristics of earth faults in distribution networks are determined based on real case recordings. Exploiting these characteristics, new applications for earth fault indication and location are then developed. The characteristics discussed are the clearing of earth faults, are extinction, arcing faults, fault resistances and transients. Arcing faults made up at least half of all the disturbances, and they were especially predominant in the unearthed network. In the case of arcing faults, typical fault durations are outlined, and the overvoltages measured in different systems are analyzed. In the unearthed systems, the maximum currents that allowed for autoextinction were small.