Determination of thermal softening of overhead wire exposed to an electric arc effect

Abstract

Systems of overhead current transfer are the main mechanism for power supply of electric rolling stock. Noncontinuous interaction of the bow collector with the overhead wire (with, from time to time, the bow collector skid detaching from the overhead wire) results in spark and electric arc formation. The most dangerous effect is the influence of an electric arc on the limited amount of overhead wire material, during which the wire heats up to very high temperatures: copper annealing (recrystallization) occurs, and soft (annealed) copper is formed. This copper has a different internal structure, which leads to poorer mechanical performance of the material. This article describes a method of determining the softening degree of overhead wire exposed to electric arc effect. The method is based on the suggested evaluation criteria. A case of calculations is given for particular conditions of the bow collector interaction with the overhead catenary. The method makes it possible to determine the degree of overhead wire softening.