Automated bus transfer control for critical industrial processes

The techniques and methods for maintaining continuous electrical power to petroleum and chemical facilities from two or more utility feeders by an automated bus transfer logic controller system are discussed. The purpose of this system is to reduce transients, torsional forces, inrush currents, and motor stress, while maintaining continuous motor operation when the primary utility source experiences an interruption and the operating facility transfers of the motor load to an alternative source of electrical supply. The economic considerations of maintaining continuity of production during power supply interruptions using a transfer logic controller to supervise bus transfers may be significant. The relay system continuously monitors the alternative source, the load bus and the normal source, and performs the necessary logic for power supply bus transfers in two directions by automatically selecting from either the fast, in-phase, or residual voltage methods. Engineering studies, application considerations, motor control design requirements, installation, and operation of the automated bus transfer controller for a chemical facility are presented and discussed