Evaluation of Prototype Short-Circuit Detector for Element Conductors in an AC Power Cord

Abstract

Short-circuiting of element conductors in the AC power cords of household electric appliances or in extension cords is one of the main causes of fire accidents originating from electric equipment. This kind of short circuit is usually observed in cords trampled by something heavy, bent and stretched repeatedly, and so on. It is not easy to detect this type of short-circuit fault with a conventional circuit breaker because the duration of a short circuit is rather short and the magnitude of the short-circuit current is smaller than the threshold for operation.

In a previous paper, the authors pointed out that a short circuit is characterized by a distortion of the voltage waveform from the sinusoidal shape. In this paper, a novel short-circuit detection method is proposed based on the results of further fundamental experiments that can distinguish a short circuit from transient phenomena when household appliances are turned on/off. Furthermore, a prototype wall outlet with short-circuit detector and circuit breaker is proposed. Its performance was evaluated under several operating conditions in the laboratory.