Multi-stage controller

摘要

A multi-stage condition control system of the time proportional type is shown. The control system utilizes a counting means as part of the anticipation for system control. The counting means counts during the time the control system is within its proportional band. When the control system moves outside of the proportional band, the counting stops. A count detection circuit senses the absence of counts thereby indicating that the system is outside of the proportional band. The absence of counts is then used to increase or decrease multiple stages of condition control equipment to bring the system back within the proportional band.