Abstract: A method and apparatus for controlling an environmental parameter is disclosed. The apparatus includes a source of energy controlled air and a source of external air. A damper determines the amount of external air and energy controlled air provided to the room. A control circuit controls the position of the damper in response to an enthalpy calculator. The enthalpy calculator includes a temperature sensitive resistor having a resistance RT and a relative humidity sensitive capacitor wherein the capacitance of the relative humidity sensitive capacitor is CS. An electronic circuit includes RT and CS and provides an output h: ##EQU1## The method includes the steps of providing energy controlled air and external air. The temperature and humidity of the external air are sensed, and the enthalpy is calculated using the equation ##EQU2## where t is the temperature and RH is the relative humidity. The amount of external air provided is adjusted using the calculated enthalpy as a parameter.

Abstract: A positioner for use in pneumatic systems moves a pneumatic operator. The positioner is an electronic pilot positioner or electronic to pneumatic interface which provides accurate positioning of linear actuators in response to an electronic control signal. The actuator is moved as pneumatic fluid is exhausted or supplied through the exhaust valve and supply valve. The positioner utilizes two solenoids for controlling a supply valve and an exhaust valve. The positioner includes a control circuit which receives a signal from a central controller and a signal from a feedback circuit. The control circuit compares the feedback signal and the controller signal and generates a signal for positioning the actuator.

Abstract: A motor-driven rotary actuator includes an electric drive motor adapted to be configured for providing one of a plurality of output torques. A power transmission is coupled to the drive motor and includes a rotatable output shaft and drive elements adapted to be formed of disparate materials selected for transmitting one of the output torques. An electric controller is coupled to the motor for providing rotation positioning control of the output shaft in response to digital command signals.

Abstract: A method of controlling a space heating system having a plurality of electrical resistance heaters includes the steps of computing the aggregate number of resistance heaters required to be energized to raise the actual temperature within a space to a set point temperature. This aggregate number may have integer and fractional components. One of the resistance heaters, denominated a controlled heater, is adapted both for continuous energization or for modulated control by intermittent energization. A group of second resistance heaters is adapted for continuous, staged energization, this group including a number of heaters equal to the integer component. Energization of the heaters comprising this group is preferably sequential after the lapse of a preselected interstage time delay between energization of the controlled heater and the first heater of the group.

Abstract: A motor-driven rotary actuator includes an electric drive motor adapted to be configured for providing one of a plurality of output torques. A power transmission is coupled to the drive motor and includes a rotatable output shaft and drive elements adapted to be formed of disparate materials selected for transmitting one of the output torques. An electric controller is coupled to the motor for providing rotation positioning control of the output shaft in response to digital command signals.

Abstract: The compressor motor controller of the present invention includes a hot motor detector adapted to be coupled to a plurality of temperature sensors for detecting an overtemperature condition of the compressor motor. The hot motor detector incorporates logic switching means for generating a motor control signal. A self diagnostic sensor is coupled to the hot motor detector for detecting an electrically shorted condition of the temperature sensors while a low voltage detector is coupled to the hot motor detector for sensing a low line voltage condition. Means are provided for protecting the compressor motor against the undesirable effects of short cycle operation while a lubricating oil pressure detector receives signals from a pressure transducer which are representative of oil pressure.

Abstract: A motor-driven rotary actuator includes an electric drive motor adapted to be configured for providing one of a plurality of output torques and power transmission means including a rotatable output shaft. The transmission means is coupled to the drive motor and includes drive elements adapted to be formed of disparate materials selected for transmitting one of the output torques. An electric controller is coupled to the motor for providing rotation positioning control of the actuator output shaft in response to analog command signals.

Abstract: An ignition system for use with a source of dc (or full-wave-rectified) power without the need for an inverter includes a flame sensing relay and a checking relay interlocked to achieve lockout if the proper starting sequence or timing are not met or if a flame-out occurs during operation. The checking relay is energized in response to a call-for-heat signal to isolate the flame detection circuitry from its source and commence a trial-for-ignition period in the flame detection circuitry which includes a timing circuit. The timing circuit actuates the flame-sensing relay during the trial-for-ignition period. The flame sensing relay energizes the fuel valve and a spark generator to ignite the fuel. If a flame is detected during the trial-for-ignition period by a flame probe, the timing circuit is disabled and operation continues until the call for heat is terminated as long as the flame is sensed. Another circuit senses flame at the spark gap and disables the spark gap generator after a flame is established.

Abstract: A motor overheating protection circuit includes an enabling circuit which responds to a trigger signal provided by a reset circuit upon application of power to the protection circuit to enable a motor drive circuit to effect energization of the motor. A temperature sensing circuit provides a control signal indicative of the temperature of the motor, and should the control signal exceed the set point of a threshold detecting circuit of the enabling circuit, indicative of overheating of the motor, the enabling circuit inhibits the motor drive circuit deenergizing the motor. Once the motor has been deenergized as the result of an overheating condition, the reset circuit maintains the enabling circuit locked out until the protection circuit is deactivated and then reactivated.

Abstract: A proportional motor control circuit for supplying bidirectional drive to a motor as a function of variations of a sensed parameter includes a temperature sensing amplifier which is responsive to an error signal indicative of deviations of the parameter from a set point to provide an output signal representing the direction and amount of the deviation, and a pair of operational amplifiers, each of which serves as a load for the other amplifier, which are responsive to the signal output of the temperature sensing amplifier to determine the polarity of the energizing potential applied to a D.C. motor over motor drive circuits. The motor control circuit is described with reference to an application in an environmental control system to effect positioning of dampers located in air ducts for supplying heated or cooled air to an area in response to changes in the air temperature in the area.

Abstract: An integral motor controller circuit for supplying variable speed, bidirectional drive to a motor as a function of variations of a sensed parameter includes an amplifier circuit which is responsive to an error signal indicative of deviations of the parameter from a set point to provide an output signal representing the direction and amount of the deviation. The amplifier output signal is applied to a first motor terminal and to an input of a two-level comparator circuit which is responsive to an increasing error signal exceeding a predetermined amount to connect an energizing potential of one polarity to a second motor terminal and responsive to a decreasing error signal in excess of the predetermined amount to connect an energizing potential of the opposite polarity to the second terminal of the motor, the speed of the motor being determined by the level of the amplifier output signal.