Power as Predictor and Protector

摘要

Automation and closed-loop feedback control can spell disaster for efforts to perform condition-based maintenance and energy economization. As the performance of a critical component in a system degrades, an automatic controller will compensate to maintain commanded output levels. By design, feedback control works to mask the effect of "soft faults," variations and vagaries in internal component performance in a larger system that do not fully stop the system. Low refrigerant charge, slipping belts, fouled fans, vacuum leaks, and degraded hydraulic fluid are all examples of mechanical insults to a system with insidious effect: the system will continue to operate and provide apparently acceptable service and performance while an automatic controller forces more energy consumption and induced wear. Soft faults may elude even vigilant watchstanders. These situations can persist for expensively long periods before a "hard fault" finally stops the system, alerting operators but also creating a "casualty" that may cripple mission readiness.