Abstract: A method and apparatus for protecting switching elements, and in particular, thyristor switching elements, which are used to supply pulses to a capacitive load, from damage resulting from false triggering signals, i.e., triggering signals not accompanied by actual sparkover conditions in the load. Since termination of normal pulse cycles in such pulser systems are accomplished by a return to high forward voltage across the switching elements, false triggers generated closely prior to such termination and within the forward recovery time of a thyristor switching element present a danger that the termination of a normal cycle will result in a weak turn-on and consequent damage of the switching element. By insuring that all such potentially false triggers have a duration which extends past termination of the pulse cycle damage to the switching element resulting from such false triggers is inhibited.

Abstract: A method and apparatus for protecting switching elements, and in particular, thyristor switching elements, which are used to supply pulses to a capacitive load, from damage resulting from sparkover occurring in that load are described. The load voltage pulse is characterized by a period of rising voltage followed by a period of falling voltage, these two periods being separated by a transition period of maximum vulnerability of the switching element to damage from sparkover. Specifically, during this period of maximum vulnerability of the switching elments to damage, a gate trigger pulse is applied to the elements to cause them to resume a conductive state, independent of the occurrence of an abnormal sparkover condition.

Abstract: A gas discharge lamp is started with a high frequency AC signal from an oscillator and then operates on a low frequency AC signal provided by an AC to AC converter synchronously with the AC supply line. The low voltage switching devices of the converter are protected from the high voltages of the high frequency oscillator by locking the converter in a single phase during starting.

Abstract: The switches of an AC to AC converter are switched synchronously with the AC supply voltage. EMI conducted to the AC power line is greatly reduced since the rectifier diodes are off at the time of switching, thus avoiding undesirable effects on nearby electrical apparatus. The converter is useful in a ballast for a discharge lamp.

Abstract: A method for simultaneously triggering a plurality of serially connected SCR's transfers energy from a relatively low voltage energy source to each of a plurality of energy storage devices which are coupled respectively to the gate of a corresponding SCR through a respective switching device. The energy from each storage device is simultaneously discharged into the gate of each respective SCR by a respective trigger signal from the low voltage energy source to each respective switching device.Apparatus for simultaneously triggering a plurality of serially connected SCR's comprises a pulse transformer for transferring energy from a relatively low voltage source of energy.

Abstract: A fault location system for use with sealed, gas-insulated electrical power apparatus. The system includes a sensor for placement in close proximity to the outer surface of a housing of the apparatus and a detector for in-place reading of the sensor. The detector comprises a first fluxgate magnetometer for detecting magnetization of the sensor. A second fluxgate magnetometer is positioned adjacent and parallel to the first magnetometer to detect only the background magnetic field. An alternating current electrical signal is applied to the magnetometers. A direct current is then automatically generated wherein the direct current is a function of the even harmonics of the ac output of the second magnetometer. The direct current is used to cancel the effects of the background magnetic field detected by the second magnetometer. As such, the direct current is applied to the first magnetometer to cancel the effects of the background magnetic field therefrom.

Abstract: Four switching elements are configured to reduce the voltage of either an alternating or a direct current electrical power source. The present circuit effectively operates like a variable autotransformer when used with a.c. input power. Additionally, when employed with a conventional resistive load, the present invention exhibits a power factor near unity.

Abstract: A data transmission system and method is provided for transferring digital information which has been converted to a multiframe format of serial bits over a single optical cable. The mutliframe format used by the system includes sequential data frames each containing a sequence of bits at a bit frequency, of which a certain number are data bits containing the digital information. The data frames are transferred by way of the optical cable to a receiver. In the receiver a clock signal is generated by a variable oscillator which operates at a frequency substantially equal to the bit frequency. Circuitry responsive to the bits maintains a predetermined phase relationship between the clock signal from the oscillator and the bits. Decoder circuitry receives the transmitted bits and decodes the bits to retrieve the digital information using the clock signal from the oscillator.