Possibilities of diagnosing the condition of contact wire in terms of thermal wear

Abstract

The paper considers the negative consequences of thermal softening of the contact wire material under the action of an electric arc, which is thermal wear. In order to determine the degree of softening of the contact wire in real time, the methodology for assessing the condition of the contact wire of electrified railways by the value of thermal wear is presented. The presented method is based on the criterial approach. The criteria for softening the material of the wire and the transition of the material to the liquid state are introduced. By comparing the amount of heat entering the wire in the event of an electric arc (with these criteria), the contact wire is diagnosed in terms of thermal wear. Calculations have been made using the proposed method; graphical dependences of the amount of heat entering the wire element on the current intensity of the electric arc for various times of its influence on the contact wire are constructed. A device for diagnosing the condition of the contact wire in terms of the amount of thermal wear is proposed, designed to record the place of occurrence of the electric arc, to collect and transmit the necessary initial data. The operating principle of the device is described and its structural diagram is given. The use of the method for assessing the condition of the contact wire in terms of the amount of thermal wear and the diagnostic device will make it possible to quantify the degree of thermal softening of the contact wire material in order to further determine its residual life.

Possibilities of diagnosing the condition of contact wire in terms of thermal wear

“…In the method of assessing the condition of the contact wire in terms of the amount of thermal wear [14,15], a criterial approach is used. The criteria for softening the material of the wire (QCRIT1) and the transition of the material to the liquid state (QCRIT2) are introduced.…”

“…Most of the damage to the contact wire is due to wear. Wear is usually divided into mechanical and electrical [1,2]. It is proposed in papers [3,4] to introduce the concept of "thermal wear" of a copper contact wire.…”