Field Survey of Internal Overvoltages caused by Breaker Switching in Residential Low-Voltage Distribution Circuits

Abstract

Periodical inspections are normally made on indoor low-voltage distribution circuits once every four years in Japan in compliance with the Electricity Utilities Industry Law. Switching of circuit breakers in distribution panels is necessary to verify electrical safety of indoor low-voltage distribution circuits. Items tested include insulation resistance. Failure of household electrical appliances during the switching operation of circuit breakers is very rare. The main cause is considered to be switching surges. However, the reason and mechanism of failures have not been clarified. We conducted an investigation into actual conditions of switching surges in indoor low-voltage distribution systems. This paper presents the investigation results.