Abstract: A valve and method for use is provided. The valve has a valve body having an outer perimeter and an inner perimeter defining a flow path therethrough. The valve has a closure member within the inner perimeter configured to selectively close and open the flow path. The valve has a valve seat located at least partially within the inner perimeter and configured to engage a portion of the closure member when the closure member is in a closed position. The valve has a stem configured to support the closure member within the flow path wherein a portion of the stem has an actuator offset. The valve has a bearing pedestal configured to support the stem. The valve has a closure member-stem connector configured to rotationally couple the closure member to the stem while allowing the closure member to move relative to the stem along a longitudinal axis of the stem.

Abstract: An actuator for a valve assembly is provided. The actuator has an actuator body and at least one piston configured to travel within the actuator body. The actuator has an output shaft located at least partially within the actuator body and configured to couple to a valve stem of a valve wherein the output shaft has a plurality of teeth protruding from a pinion. The actuator has at least one rack configured to move with each of the at least one piston, the rack having a piston end and a terminal end and wherein the rack has a plurality of rack teeth configured to engage the plurality of teeth on the output shaft. The terminal end of the rack is configured to be maintained a minimum distance beyond an engagement point, wherein the engagement point is located between the rack teeth and the teeth in all operating positions.

Abstract: An instant-start ballast for a multiple gas discharge lamp fixture has a single half-bridge inverter that is used to drive at least two series resonant output circuits. Each series resonant output circuit is used to drive two gas discharge lamps. A single output voltage limiting circuit is provided with a microprocessor that monitors the combined output voltages of the series resonant output circuits and uses a single voltage limiting transistor to control the output voltages of the circuits. A capacitor is associated with each gas discharge lamp socket in the fixture such that a voltage across the capacitor indicates that a lamp has been installed in the socket associated with the capacitor. The ignition sequence will only be initiated if the capacitor voltages indicate that a lamp has been installed in each socket of a fixture.

Abstract: An improved high input voltage instant start electronic ballast uses a substantially lossless snubber circuit. The substantially lossless snubber circuit is incorporated into the ballast to reduce turn off losses and increase the efficiency of the ballast. The snubber circuit includes two capacitors connected in parallel with respect to the two switching transistors or FETS in the inverter of the ballast. A series-resonant lamp voltage sensing circuit is also provided that uses a voltage dividing capacitor to accomplish lossless monitoring of the open circuit voltage of the ballast. A cable compensation circuit minimizes variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast by limiting the turn on times of the transistors during high voltage conditions.

Abstract: An electronic ballast uses a voltage sampling circuit and a voltage control circuit to limit the open circuit voltage of the ballast. A lamp voltage sensing circuit is provided that uses a voltage dividing capacitor to accomplish lossless monitoring of the open circuit voltage of the ballast. A resistor placed in series with the sampling capacitor is used to create a voltage that turns a control transistor off and on. The control transistor produces a gating signal trimming signal that a half bridge driver uses to alter the gating signals provided to the inverter transistors of the ballast. A cable compensation circuit is included that minimizes variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast by turning the control transistor off and on.

Abstract: An electronic ballast has a resonant tank circuit that includes a tank inductor and a tank capacitor connected in series. Lossless sampling of the output voltage of the electronic ballast is achieved by monitoring the voltage across a sampling capacitor placed in series with the tank capacitor. A resistive and capacitive filter is used to filter the monitored voltage such that it can be accurately received by a microcontroller. A resistor is connected in series with the sampling capacitor to produce an open circuit output voltage control signal that is used by the microcontroller to limit the open circuit output voltage. A cable compensation circuit is utilized to minimize variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast output terminals. 17.

Abstract: An electronic ballast includes a microcontroller with software to provide an adaptive lamp preheat and ignition operation. The microcontroller commands a test frequency from the inverter and detects the frequency response of the resonant output circuit by measuring the voltage across the resonant capacitor. The measured voltages are compared to one or more reference voltages as the frequency is varied to select the optimal inverter frequency. An algorithm or look-up table is used to set the inverter frequencies for the lamp preheat and ignition phases.