MEDIUM-VOLTAGE CONTROLLERS SHOW ADVANTAGES OVER CIRCUIT BREAKERS.

Large utility companies are now seriously considering the use of motor controllers in place of the circuit breakers in metal-clad switchgear which have been generally used for controlling generating station auxiliary drive motors. This is because of the repetitive switching duty associated with coal handling, cooling and pumping systems, and selected station auxiliaries within a standardized fossil-fired cycling plant. The advantages of medium-voltage controllers over circuit breakers include long operating life, limited thermal and mechanical stress, reduced dependence on station batteries, simplicity and reliability space savings, low initial cost, and reduced handling, installation, testing and maintenance.