Abstract: An enhanced controller for an air conditioning system incorporating mechanical cooling equipment and an economizer, the enhanced controller including circuits for producing signals indicative of commanded changes in temperature of air admitted into the air conditioned space and of a non-temperature parameter, such as carbon dioxide concentration, of air within the space. The signals are supplied to a logic circuit which produces a ventilation damper control signal based on which of the temperature and non-temperature parameters requires greater change. Freeze protection, and maximum and minimum damper position circuits override the basic damper control signal to avoid excessively low space temperatures and to provide air exchange limits.

Abstract: An electrically operated actuator stores power in a capacitor for returning the actuator output element to a preselected position upon power failure. The actuator has a controller having input power terminals connected across the capacitor and control terminals for controlling the power applied from the input power terminals to the motor which comprises the actuator's prime mover. A sensor monitors the presence of power provided to the controller's input power terminals. When failure of this power is sensed, the capacitor current flows to the controller, and the sensor applies signals to an override circuit of the controller causing the controller to apply current from the capacitor to the actuator motor in a way which drives the actuator toward the preselected position. A properly selected capacitor is capable of supplying adequate current over a period of time sufficient to return the actuator to the preselected position.

Abstract: A bi-directional alternating current permanent magnet motor is disclosed that is operated with a rotational restraint that insures proper directional rotation of a load. The motor output shaft is loosly coupled to a pinion gear. In the event that the motor is unable to start in the correct direction, and inadvertently reverses itself, it is immediately unloaded. This unloading causes the motor to stop and start again in the correct direction with a momentum that typically is sufficient to run the motor and its gear train in the correct direction.

Abstract: A system for insuring the correct rotational direction of a permanent magnet, bi-directional alternating current motor. A sensor driven by the output of the motor provides a time varying voltage signal that is differentiated and detected. The signal is then applied to either agree with or override the output control signal from a conventional motor control circuit. When the system operates in the correct direction, the signal complements the motor control. When the device tries to operate in an incorrect direction, the signal overrides the motor control signal.