CONTROL DEVICE FOR A MELT ELECTRODE

摘要

PCT No. PCT/DE87/00487 Sec. 371 Date Aug. 10, 1987 Sec. 102(e) Date Aug. 10, 1987 PCT Filed Nov. 29, 1986 PCT Pub. No. WO87/03772 PCT Pub. Date Jun. 18, 1987.Apparatus for controlling the distance of a melting electrode from the surface of melted material in a vacuum arc furnace which uses short circuits caused by the droplets between the melting electrode and the surface of the melted material as a control criterion. The short circuits occurring within a given period of time-the so-called droplet rate-are determined and supplied to an averager which is connected with a controller that controls an electric driving mechanism for the melting electrode. According to the invention, the controller is responsive to a signal representing the difference between the reciprocal value of the droplet rate signal formed by the averager and a desired time, this desired time being equal to the desired average time between two consecutive droplet short circuits.