Microprocessors in Power Control, The Time has Come

Historically, ac reserve power systems have been limited to relay logic controls; and while some evolution into solid state controls has been realized, in general these controllers have replaced relay logic on a function-to-function basis with only limited improvement in features. With the advent of small, low cost and highly reliable microcomputer circuitry, the designer can look beyond the standard control functions of a standby system and consider integrating the processing power of the microcomputer into other aspects of the building power systems. A design example of a real-time microprocessor based controller for standby diesel alternators in a telecommunication environment will be presented. Emphasis will be placed on development considerations such as control functions necessary, hardware chosen and software implementation. The following features of the controller will also be discussed: Flexibility - The concept of functional reconfiguration whereby a single control board can be utilized in different applications via software changes. Testability - Onboard self-diagnostics for field service and interfacing with automated production test equipment. Expandability - Bus oriented structure as a vehicle for expanding processor power to other applications and multiprocessor interface. The single board microprocessor based controller is presently in production, and its base objectives of reduced cost, increased reliability and testability over its sequential logic counterparts have been realized.