A Method for Calculating of Нeating Closed High-Current Electric Contacts by Pulsed Currents

We propose an original method for numerical calculation of heating of high-current electric contacts in the closed state by pulsed currents with a duration comparable with the period of the industrial-frequency current. Such regimes are typical of current-carrying systems of high-voltage electric facilities during switching high-power loads, during failure in electric transmission lines, and in testing devices for stability to short-circuit current. In constructing the solution, we assume that the time dependences of the current and voltage across the contacts are known. We have developed an iteration procedure for solving a series of thermoelectric problems, which makes it possible to calculate the temperature distribution in contacts and to trace its variation by selecting the size of contact spots in each time interval. We have tested this method by comparing the results of calculation with experimental data obtained for cylindrical copper contacts heated to melting by pulsed currents in a wide range of contact pressure forces. The current actions are selected so that melting occurs during extremely short time (first quarter of the period).