New Theoretical Model of Electric Arc in Circuit Breaker and the Role of Parallel Resistance – The Shunt

Abstract

Aims: The paper presents a new theoretical model of an electric arc in a circuit breaker with reference to the role of shunt resistance parallel to the electric arc in a circuit breaker switch. One of the goals of the paper is to show the efficiency of using the software package MATLAB Simulink in which the previously derived system of equations is easily implemented in the blocks of the mentioned software package. Methodology: The discharges in the electric arc determine the potential between the metal contacts of the switch and the structure and shape of the electric arc make it difficult to solve the transient process. The main step in solving the problem is the formation of a theoretical model of the electric circuit from which the current and voltage can be determined, which depend on the parameters of the electric field in the arc. The use of shunts in oil and air switches, due to a number of shortcomings, was not possible, but the disadvantages are overcome if thyristors are used to interrupt the current. The equations and the algorithm for solving the problem are obtained from the parameters of the electric field potential that shape the electric arc and its path. The accuracy of the theoretical model is confirmed by voltage and current diagrams in the adapted MATLAB Simulink software package. Conclusion: The presented theoretical model and algorithm are universal and can be used for different states in which an electric line can be found. Problems that occur in the analysis of transient processes in an electric circuit where an electric arc occurs can be minimized using different types of simulations. Changing any parameter in the electrical circuit requires a new calculation of the state of the circuit from the very beginning due to the new initial conditions. Analytical methods combined with the simulation method were used in the research of overvoltages, asymmetries and harmonics during the appearance of an electric arc. The MATLAB simulation program had a threefold purpose: to serve the calculation and simulation of quantities that can be obtained by testing or measurement, to establish the original algorithm and to verify the proposed method. Also, this type of simulation can replace the type tests of the electric arc on the switch.