Automatic Control of Air Switches for Line Sectionalizing and Load Transfer

The considerations involved in the design and application of automatic control of air switches are discussed in this paper with the thought that they might be used to guide designers and engineers who encounter similar problems. Three air break switch control schemes are described and the diagrams involved are shown. These control schemes were designed to provide automatic switching as follows: 1. Load transfer with synchronism check interlock, using direct current for operation and control. 2. Line sectionalizing and subsequent load transfer, using direct current for operation and control. 3. Load transfer, using alternating current for operation and control. The description outlines the operation of the various control devices for manual switching and for automatic switching which occurs during fault conditions.