Transit system third rail de-icing by radio frequency induction

Radio frequency induction is investigated as a method to debond ice from high permeability magnetic steels. The application of interest for this work is the deicing of a transit system's third rail. The objective is a system which will keep third-rail systems operational during severe winter snow and icing conditions. The basic operating scheme is that of passing a RF induction coil over a section of iced rail. The RF energy is absorbed in the skin depth ( approximately 200 mu m) and melts a thin ice layer at the ice/steel interface. A scraper brushes the ice aside, just prior to passing of the sliding electrical contact. Many criteria are considered in the design of the overall deicing system. Adequate power must be applied to the rail by the RF coil in order to effectively debond the ice at operating speeds up to 30 mph. While laboratory work has been conducted using a frequency of 450 kHz, the practical design uses 50 kHz as a compromise between economical solid-state RF sources and high magnetic flux densities.<
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