On the applicability of the Mayr arc model for studying current chopping and overvoltages generated by low-oil current breakers

Abstract

A significant number of low-oil circuit breakers are currently in operation. They are considered obsolete and inferior in their characteristics to more modern types of switches—vacuum and gas-insulated circuit breakers. When triggered, low-oil circuit breakers can serve as sources of considerable overvoltages, one of the causes of which is the current chopping that is connected with the arc-extinction mechanism in a dense environment. Current chopping usually occurs when small inductive currents are disconnected, for example, the no-load current of transformers and electric motors. When arc processes in circuit breakers are investigated, various methods are used, including adaptive ones (the “black box” method). This paper considers the possibility of using the arc model on the basis of the Mayr equation for studying the phenomena of current chopping and overvoltages that are generated by a low-oil circuit breaker. The features of constructing such a model are analyzed, and its structure, appearance, and description are presented. The model was constructed in the MATLAB software package. The case of the RLC-circuit disconnection from a source of a low-resistance EMF was considered taking the arc-extinction mechanism into account. This circuit simulated the switching off of an electric motor that was connected via a cable line. This article also presents s comparison of the experimental and calculated data.