摘要:
A damping control system for a three phase stepper motor. A reluctance velocity transducer is used for each of the three phases. The output of each of the transducers is proportional to the rotational velocity of the motor. Each of the transducers is rotationally phase shifted 3.75 with respect to one another and phased to the motor rotor rotationally such that the zero voltage crossings of the transducers correspond to the zero torque crossings of the motor. During damping or detenting of the motor the selected phase has current applied to it which is equal to a predetermined fixed value plus the feedback from its associated transducer. The windings on each side of the detent position have current applied to them which is proportional to the voltage from their respective feedback transducers. The voltage in each of the windings is amplified by a selected gain constant. The current in each of the windings is such that maximum torque is applied to drive the motor to the detent position with appropriate current reversals in the windings to damp out any kinetic energy in the rotor during detenting.
摘要:
A method and apparatus for measuring the content of carbon dioxide in an aqueous medium, particularly boiler condensate from an electrical power plant. The apparatus comprises a container or housing defining an elongated vertical indicator chamber and a parallel vertical reference chamber which are connected by a generally horizontal passage. An indicator electrode and a reference electrode are mounted in the indicator chamber and reference chamber, respectively. The lower end of the indicator chamber is open, and the open end is enclosed by a membrane of microporous polytetrafluoroethylene. The lower end of the indicator electrode is flat or planar and is located in close proximity to the inner face of the membrane. A filling liquid consisting of pure water is located within both chambers in contact with the respective electrodes. The apparatus can be mounted in a condensate bleed line of a power plant. The condensate in the bleed line is in initially adjusted in pH to a value of about 4.5 and then is flowed in contact with the outer face of the membrane. Carbon dioxide in the condensate will diffuse through the membrane to provide a differential in electrical potential, which serves as a measurement of the carbon dioxide content.
摘要:
In an impact printer including a print wheel having a plurality of selectable character type bearing elements for respectively printing a plurality of characters, said print wheel being rotatable for selectively positioning selected type elements in successive print positions, impact means impellable against the selected elements to drive said elements against the printing medium and means for impelling the impact means against said selected type element, the present invention provides the improvement comprising the combination of means for sensing the flight time of the impelled impact means until impact by sensing variations in the velocity of said impact means, means for comparing the sensed flight time to a predetermined ideal flight time, and means for selectively varying the amplitude of the current to the impelling means to adjust the sensed flight time to equal the ideal flight time.
摘要:
A computer controllable testing and monitoring station forms short-term intervals of simulated alternating current power level disturbance, either undervoltage (sag) or overvoltage (swell). The station forms the short term voltage sags or swells so that their effects on sensitive equipment can be measured. The starting point of the sag or swell disturbance, as well as the time duration of the disturbance, can be accurately controlled.