Abstract: An AC contactor having a high recovery voltage strength includes a contact assembly and a high recovery voltage gas system coupled to the contact assembly. The contact assembly includes two contact pads per electrical phase, with one of the contact pads being attached to a positioning device that selectively disposes the contact pad between a closed circuit position and an open circuit position. The high recovery voltage gas system includes a thermal gas evolving medium for introducing a high recovery voltage strength gas into the gap between the contact pads, which gas has a high glow discharge cathode voltage fall value, as determined for silver-based contacts, of not less than about 300 volts, and typically greater than about 500 volts. The high recovery voltage strength gas typically comprises carbon monoxide, carbon dioxide, water vapor, or the like. The thermal gas evolving medium typically is as a Group IA carbonate (e.g., sodium bicarbonate), and is disposed in the contact assembly.

Abstract: This invention relates to an apparatus and method for directly measuring the bottom pour flow rate from heated ceramic crucible, hearth/tundish combinations used in metals refining/processing industry, plasma arc melting process (PAM), a cold hearth process or other similar processes such as for pouring ingots. Such structures of this type generally allow the bottom pour flow rate to be accurately measured in relative real time without adversely affecting the flow while withstanding the hostile surroundings typically associate with a heated crucible, tundishes, PAM, cold hearth process or other similar processes.

Abstract: A tool break detection system has an automatic gain control to adjust the analog signal channel gain and hold the cutting vibration signal at a desired average level. The AGC time constant is long enough that the detection of abrupt tool breaks and sudden large signal level transistions by the digital signature recognition logic is unaffected. However, the gradual decrease in signal level produced by a crumbly-type break would be removed by AGC action. In a system with a hardware AGC, crossing a high gain threshold resets gain to a low value and the resulting abrupt and persisting change in signal level is detected by the abrupt tool break logic. Another embodiment uses the gain command output by a software AGC and generates a break detected signal directly, without resetting the gain command, as gain rises above a high gain alarm level which is recalculated at the start of each cut.

Abstract: Composites such as graphite reinforced PMR-15 resin are cured in a heated press by following a temperature schedule and changing from low to high pressure after the start of resin cross linking. A pressure control and method to time application of high pressure uses temperature and dielectric sensor outputs and a semi-empirical model of the resin electrical conductivity. The model estimates the future variation of resin conductivity and determines time-to-go to a maximum in electrical conductivity. A signal to apply high pressure is generated when the estimated time to maximum conductivity falls below a threshold. On-line fitting of the model to sensor data as it is gathered provides a mechanism for adapting the control to the peculiarities of a given batch of resins and a particular cure schedule.

Abstract: A Machine Tool Monitor detects significant cutting tool breakage and the first contact of an advancing tool to a workpiece, and does this by monitoring vibration signals produced by the machining of parts and interpreting patterns in these signals. Information from the part program improves the performance of the detector and optimizes it for the cutting conditions called for by the machine tool control. The analog channel gain of the monitor is adjusted and parameters controlling the digital pattern recognition logic are selected using part program information on machining parameters. The tool touch or tool break detection mode is selected by the part program.

Abstract: An RLC triggering circuit employs an inductance coupled to the trigger electrode of a triggered vacuum gap device. A capacitance and a switch are coupled in series with the inductance. A diode in parallel with the series-coupled capacitance and switch serves to provide a long, unidirectional current pulse to prevent the triggered vacuum gap from chopping current and generating dangerous surge voltages.

Abstract: When the butt contacts of a vacuum arc discharge device are parted, at least one of the contacts is withdrawn into a high dielectric strength shield, giving the device high current interruption capability. The shield may be grounded to an endwall of the device or electrically isolated therefrom. Facing the stationary contact with a hardened steel enables it to withstand the dielectric stress extant at recovery. Facing the moving contact with a refractory material allows high current and voltage interruption capability without adversely affecting current chopping performance, while limiting contact erosion and weld forces.