Abstract: Apparatus for determining the size adequacy of a current transformer in an electrical power distribution system. The apparatus includes a voltage generating source for connection in series with a current transformer secondary circuit, which source saturates the current transformer. A first signal is provided which is indicative of the voltage required to cause the current transformer to enter saturation. A second signal is provided which is indicative of the resistance of the secondary circuit of the current transformer after saturation. A third signal is then provided which is responsive to the product of the second signal and predetermined constant value. A ratio of the first to the third signals which exceeds unity indicates adequacy of the current transformer for a given system.

Abstract: An improved apparatus for the "on-line" measurement of the dielectric constant or percent moisture of a material such as tobacco moving within the walls of a pipe or chute is disclosed. A differential capacitive technique is used for the measurement. The apparatus consists of a four electrode device, with two of the electrodes attached to the outside of the walls of the pipe or chute, and two of the electrodes attached to the inside of the walls of the pipe or chute. The two inner electrodes are connected by switches to the two outer electrodes, respectively, so that first and second capacitances appear at the output terminals of the electrode device depending upon the position of the switches. The output terminals of the electrode device are connected to an oscillator which produces an output signal indicative of the frequency of the oscillator's oscillation which is proportional to the capacitance at the terminals of the electrode device.

Abstract: Apparatus for precisely and quickly measuring the length of a line under test to an electrical discontinuity of the line, the apparatus including an edge generator for providing an edge to one end of the line, a reflection detector for detecting the edge reflection returning from the discontinuity to the one end and triggering the edge generator to provide an edge at a fixed time after detecting the edge reflection so as to cause the edge generator to repeatedly provide the edges at a frequency related to the propagation delay in the length of line, and a frequency measurer connected to measure the frequency.

Abstract: A method and apparatus is disclosed for induction heating weldable surfaces and moving the heated surfaces together with sufficient force to upset the surfaces while in a substantially inert atmosphere for thereby welding the surfaces together. The apparatus includes a rotary bus bar joint for moving the induction coil between the weldable surfaces, and also includes a clamping mechanism for handling members having weldable surfaces of different sizes and shapes. A pair of separately controlled induction coils may be used with or without laminations for heating tubular or solid members to an upsetting temperature.

Abstract: A power relay control circuit for a microwave oven including a microprocessor as its controller is provided, wherein two power relay driving transistors are to be turned on or turned off by a thyristor, which is triggered by a switching transistor, and a stabilizing circuit respectively. Two signals of different levels from terminals of the microprocessor are supplied to the base of the switching transistor and the stabilizing circuit in order to make the oven start heating operation. If the microprocessor operates in all possible abnormal states, both signals from the terminals of the microprocessor are to become the same level, all HIGH or all LOW, making either of the power relay driving transistors turned off, resulting in preventing power supply from being applied to the power relay.

Abstract: A welding control circuit for induction heating of a pair of articles to a welding temperature and for pressing the heated articles together. A pair of induction coils are positioned in a gap between the portions of the articles to be heated and a pair of temperature sensors monitor the temperature of both articles and controls heating rates so both articles reach a welding temperature at approximately the same time. The temperature sensors provide signals which cause the coils to be retracted from the gap and cause the heated articles to be pressed together to form a welded pair. When similar articles are to be welded together a single coil can be used to provide induction currents which heat the articles.

Abstract: An adjustable length linear bus bar for conducting a current between an induction heating power supply and an induction heating coil. The bus bar includes a fixed bar having a channel formed along the length of the fixed bar and a movable bar having a portion formed to slidably fit inside the channel of the fixed bar. A hydraulic ram biases the slidable bar against the fixed bar to facilitate the transfer of current between the fixed and movable bars. A clam shell type of construction allows the inductor coil to be quickly moved into and out of a gap between a pair of articles being heated.

Abstract: The invention relates to a microwave oven comprising control means which reduce the risk of no-load operation and which co-operate with an actuating element which switches on the magnetron with the aid of power-supply means depending on open and closed states of the oven door. The invention is characterized in that the control means comprise a bistable electromechanical device which responds to closures of the door by counting the number of these closures and which enables the magnetron to be energized after an even number of closures of the door, one cycle of operation of the bistable electromechanical device comprising two open states and two closed states of the door. The bistable device may comprise a lever device which actuates a pendant-type electrical switch or a remote-controlled switch.

Abstract: A microwave oven door is disclosed having a channel cross-section and formed of plastic material having a microwave impermeable viewing window, hinge means, door securing means, and a microwave impermeable coating in the channel cross-section area. An alternative embodiment has the channel cross-section area formed of a plastic filled with a microwave blocking material. A further embodiment has a microwave impermeable opaque surface in place of the viewing window.

Abstract: A method and apparatus is provided for reducing and measuring carbon content in fly ash. The invention employs microwave energy as the method of heating for inducing combustion of the carbon in a fly ash sample. Measurement of the carbon content can be accomplished in accordance with the present invention by measuring temperature differential of an excess energy absorber in the form of water before and after the fly ash is exposed to microwave radiation.

Abstract: An improved system for mounting a magnetron exterior to a microwave oven chamber. A magnetron antenna extends through an orifice in the chamber wall and mounting clips extend from the chamber walls at locations spaced around the orifice. Apertures are provided within the keeper plate of the magnetron to allow the clips to pass therethrough and engage a keeper plate interface on relative rotation of the chamber wall and plate. The clips may be formed as part of the chamber wall.

Abstract: A device for preventing twist of a connecting line for a temperature probe in a microwave range. An electromagnet which is automatically actuated according to a connecting rod being inserted into a jack is provided so that a steel piece of an activating lever is attracted thereto to result in a stopping pin of the activating lever being outwardly extruded from a fixing plate through an opening. A disk having a protrusion at its peripheral surface is mounted on a rotating axis of a synchronous motor in such a manner that the disk is repeatedly rotated, invertedly in its direction every time the protrusion is contacted with the stopping pin.