Abstract: An HID lamp incorporates all-metal electrodes providing rapid transition of the arc to the electrode tip. The electrode comprises a length of thoriated tungsten wire having a close wrapped coil between connection and tip ends, so that rapid heating of the electrode tip promotes rapid transition of the arc from coil crevices to the tip.

Abstract: A high-intensity discharge lamp which has a lamp current-interrupting device in series circuit with the arc tube which is sensitive to any breach occurring in the protective outer envelope. The current-interrupting constituent of the device initially incorporated into the lamp comprises vanadium sesquioxide. The device has predetermined dimensions and an initial predetermined operating resistance. During normal operation of the lamp the device operates at a predetermined temperature sufficiently low so that said device is stable in the presence of the non-reactive atmosphere enclosed by the outer envelope. The predetermined temperature also being sufficiently high so that upon a breach occurring in the outer envelope permitting oxygen to enter, the vanadium sesquioxide rapidly converts to vanadium pentoxide to interrupt the continuity of the power circuit to the arc tube and prevent the operation of the lamp.

Abstract: Current inrush limiter for incandescent lamps is made by mixing finely divided vanadium sesquioxide and vanadium pentoxide with finely divided glass-forming constituents which include vanadium compound. The mix is compacted and sintered in a substantially inert atmosphere which converts the vanadium oxides to vanadium dioxide maintained in a chemically stable and mechanically strong mass by vitreous binder.

Abstract: An improved composition of VO.sub.2 current inrush limiting ceramics for incandescent lamps using a 0.003-0.06 weight percent MoO.sub.3 addition. This addition modifies the resistance-temperature relationship to provide a more gradual transition and also to provide a resistance which varies less at temperatures below the transition temperature. The more gradual change is desirable as it reduces the tendency for a delayed current overshoot and also reduces the tendency for the current to be funnelled through a relatively small portion of the thermistor. The more nearly constant low temperature resistance provides good current inrush limiting in a wider range of ambient temperatures.

Abstract: An arrangement to eliminate the initial current overshoot which normally occurs when a tungsten incandescent lamp is connected to a power source. The arrangement uses a negative temperature coefficient thermistor having a certain predetermined mass. It has been determined that a practical limiter to eliminate current overshoot can be made only when the mass of the limiter is within a relatively narrow range. The hot and cold resistance of the limiter must also be within prescribed ranges to give a limiter which is not only effective in eliminating the current overshoot, but also efficient in steady state operation such that the limiter dissipates less than 1% of the total power.