Abstract: A constant current arc welder of the type in which arc current is regulated by thyristor phase angle adjustment, includes voltage feedback voltage control and current feedback current control, with automatic transfer from the voltage control mode into the current control mode when current has been established in the arc. A time delay allows smooth transfer to the desired current operative level by limiting the current inrush under an initial current reference and with a chosen feedback control dynamic characteristic current boost is also automatically provided when the arc voltage falls below a predetermined level.

Abstract: Non-dissipative filtering of a DC voltage, or current, is provided with an energy storage inductor coupled sequentially in alternate directions across the DC source. In another embodiment the inductor is part of the primary of a transformer and secondary DC voltage is derived by rectification. In a further embodiment, a thyristor and a diode respectively at opposite sides of the transformer and a capacitor at the output of the rectification unit concur in limiting the transferred DC energy to a selected level by control of the firing angle of the thyristor.

Abstract: An improved wire, rod, stick, and the like to be stored, packaged, transported, and fed into welding apparatus is manufactured so that the ultimate alloying stage is performed when used as filler material, or consumable electrode during welding operation. The wire, rod, stick, according to the invention, which may be with or without fluxing agent, is obtained by selecting constituents in relation to a desired alloy system, mixing the selected constituents, and forming a wire, rod or stick cold working, or by extrusion, the alloy system being obtained at the ultimate welding step with the intermediary wire, rod or stick.

Abstract: A phase detector circuit is connected to a sine wave reference during a time interval of one-half cycle of the sine wave to be compared. Phase detection is provided by integrating the inputted sine wave reference during such time interval, and immediately following such accumulation of information, the latter is transferred to a holding circuit. The phase detector is applied to a phase locked loop in which the time intervals are established digitally to control FET devices for the sampling and holding functions.

Abstract: A variable length delay line comprises a random-access-memory (RAM) device in which a selected shift between read and write addresses establishes the desired amount of delay.

Abstract: In a power utilization system having loads drawing energy from a utility company, some loads are adjustable and, as part of computerized power demand control system, loads are regulated as well as switched ON or OFF in order to meet an assigned power demand limit. The adjustable loads draw power in accordance with a local supply controller, such as a tap changer, but regulated amounts of power are established by the computer with a set point which is a function of the demand error calculated in an outer loop by the power demand control system and maintained by the computer in a closed loop from an individual power meter and with the established set point. The priority schedule and error computations take into account the amounts of power drawn by adjustable loads as well as the amounts drawn by loads which can be shed, or reconnected.

Abstract: The invention provides a bilateral static isolator which is activated by "soft" forced commutation. Between two points in the power line to be interrupted are connected two thyristors in series-opposition, thus cathode to cathode. In antiparallel with each thyristor is mounted a diode. Thus, the two diodes appear in series opposition between the two power line points. A resonant circuit is applied to the conducting thyristor in order to turn it off with a relatively small reverse voltage. This voltage is obtained by resonant discharge of a precharged capacitor C through an inductor L and a diode D connected in reverse with the thyristor. The forward voltage drop of the diodes appears in reverse across the thyristors from the instant the discharge current rises above the line current until the instant the discharge current drops below the level of the line current. It is during this interval that the thyristor is provided with "soft" reverse bias. Subsequently the net current reverses again.

Abstract: A load is driven by a statically controlled motor drive so as to follow a linear ramp characteristic recurrently, and a jump is caused to occur after each peak of the controlling ramp signal in order to compensate for inertia in the driven load. The inertia compensating jump is adjustable independently from the ramp parameters, and each ramp parameter is adjustable independently from the others as well as from the adjustment of the jump.

Abstract: Power demand control on a plant having a plurality of load units of production, each operating between a starting time and an ending time to provide individual production outputs, is exercised by automatically shedding or restoring such load units in order to maintain power demand within an assigned demand limit. The control system provides adaptive priority determination by storing an image of the ON, or OFF, status of the load units into at least two memories (memory I and memory II) on a last ON, first OFF basis for the loads to be shed, and on a last OFF, first ON basis for the loads to be restored. Loads that are ON are stored in a first (ON) memory (memory I); loads that are being held OFF by the controller are stored in a second (DCOFF) memory (memory III). Also provided is a third memory (OFF) (memory II) to store the status of load units which are out of production and under independent control either after ending production or while being made ready to start production.

Abstract: A firing pulse generator for sequential firing of thyristors digitally synthesizes time dependent references associated in succession with the respective thyristors with a hard pulse, and predetermined critical counts on a time dependent reference are identified representing the first and second end-stops defining the permissible fire-angle range. A substitute for the hard pulse is generated when the hard pulse is advanced, and when it is retarded in relation to predetermined limits, e.g. the end-stops. The time dependent reference is generated over a range sufficient to cover the permissible fire-angle range defined by the end-stops. Blocking of an illegal hard pulse is effected independently from the generation of a hard pulse. Pulse suppression is performed independently from the generation of a hard pulse, or of a substitute pulse.

Abstract: A commutation circuit for thyristors alternately turned ON by pulse width modulation (PWM) for the generation of a fundamental sine wave is characterized by two separate primary windings associated with respective positive and negative thyristors with a common secondary winding at the output, and two commutating networks for the respective poles, each including an auxiliary thyristor for fixed-commutation and the resonant combination of a capacitor and an inductor. The thyristors, the commutating networks, the DC source, and the output transformer have a symmetrical disposition as well as symmetrical commutation steps.

Abstract: A symmetrical phase shifter generates two signals shifted symmetrically from an inputted single signal, using digital delay lines.

Abstract: A spinneret pack comprising a filtration assembly and an outer ring surrounding the spinneret plate, when it is clogged with unprocessed plastic material, is preheated by induction heating to separate the outer ring by slight pressure in a first processing step, then a second induction heating treatment separates the spinneret plate from the attached filtration assembly. The spinneret plate, detached by gravity, has matter in the die holes carbonized by the second induction heating process, thereby simplifying a final cleaning process which will make the spinneret plate reusable in the synthetic fiber manufacturing process.

Abstract: Plug reversal of an induction motor supplied by an N-stage inverter system operating under harmonic neutralization technique is provided by reversing the polarity of the square-shaped voltages combined at .pi./N from each other and by reversing at the same time the sequence of the stages as well as the logic of dissection of the reference time wave. A mirror image of the time scale is effected at the instant of reversal. Digital means are used. Reversible ramp forming generators of the UP-DOWN type are associated in each stage with a phase shifter in order to create the mirror image of the logic controlling the inverter system. A reversible ring counter is used to reverse the sequence of the stages. A reversible pulse generator is used to accommodate an integer number of elementary time intervals in each ramp and between each ramp for the given number of stages.

Abstract: A power demand control method uses a temporary demand limit in excess of the demand limit assigned as a target at the end of the demand period, and such temporary demand limit is reduced by steps from control point to control point until it coincides with the assigned target at the very end of the demand period. More specifically, the demand limit used for prediction is reduced by a major portion always the same from predicted demand error to the reset, thereby progressively reducing the same down to zero at the end of the period.

Abstract: The invention relates to power demand control of a number of loads in a plant facility in order to keep the power within a demand limit at the end of a demand period. During the billing period the invention provides for a demand limit floating up and/or down over the demand periods, and means is provided to dampen control action whenever the demand limit would tend to oscillate up and down over the successive demand periods.

Abstract: A voltage controlled AC static power supply of the harmonic neutralization type uses symmetrical digital phase shifting in order to reconstruct, with pulses of variable width and predetermined different magnitudes generated by inverters, a sinusoidal wave of fundamental frequency. Phase-shifts are obtained digitally from a single pair of frequency signals. Variable length delay lines are used consisting of random-access-memory (RAM) devices in which a selected shift between read and write addresses establishes the desired amount of delay.

Abstract: A data processing system includes a shared functional unit having access and egress through a plurality of communication channels to several data handling units. The communication channels are multiplexed under control of a priority selection circuit normally arranged as a ladder from highest to lowest priority. Request signals for the various channels are each passed through a respective gate conditioned by a request enable device which is susceptible of being disabled whenever a select signal for that particular channel has been caused to serve the associated handling unit while channels of lower priority have request signals still demanding selection. When the request signal of lowest order at the time has been served, all request enable devices are reset in order to return to full priority selection.

Abstract: A dual converter for use in a static direct current motor drive is operated with circulating current and the circulating current is adjusted by firing angle control to automatically maintain reactive power compensation during varying torque and speed conditions of the load.

Abstract: In an inverter system using parallel transformers to generate a reconstructed sinewave by harmonic neutralization method direct current offset in any of the transformers is eliminated by shifting one edge of one of the square pulses logically determining the conduction angle of the inverter.A hall device mounted in an auxiliary reactor connected with the primary of the transformer is used to sense flux conditions during sampling periods which are in time relation with the logic period in the control of the inverter system and the detected flux asymmetry is used to control the ON-OFF ratio of such logic period thereby to compensate for the offset.