The Mechanism of the Contact Resistance between Rail and Wheel in Bad Shunting Area

摘要

The bad shunting of track circuit results from the contact resistance between wheel and rail and its solution becomes a disturbing problem for electrical engineer technicians. Based on the Holm electrical contact model, Greenwood model and thermal breakdown theory, this paper analyzed the mechanism of contact resistance between wheel and rail. Then breakdown characteristic of the imperfect electrical layer is analyzed. Through field test, its character is similar to reversed breakdown of diode and the contact resistance decreases as the current ascending. The conclusions of the experiments not only prove the validity of Holm and Greenwood model, but also provide the professional and practical parameters for solving bad shunting. And these parameters involve the breakdown voltage and short-circuit current.