Abstract: A method and apparatus for providing submerged arc welding power is disclosed. The power supply is AC/DC, and may be controlled in either a CV or a CC mode. The power supply includes a cycloconverter that provides a single phase output and receives a three phase input. A controller includes a PI current regulator for operation in the CC mode. The controller also includes a PI voltage regulator. When the CV mode is selected, the voltage and current regulators are cascaded such that the output of the voltage regulator is the set point input to the current regulator.

Abstract: A welding power supply includes an input rectifier that receives sinusoidal or alternating line voltage and provides a rectified voltage. A pre-regulator provides a dc bus and a convertor, such as a boost convertor, provides a welding output. The pre-regulator is an SVT (slow voltage transition) and an SCT (slow current transition) switched convertor. It may include a snubber circuit having a diode that is SVT switched. Also, the boost convertor may be SVT and SCT switched. The pre-regulator preferably includes a power factor correction circuit. The power source includes, in one embodiment, an inverter having a snubber circuit having a first switch in anti-parallel with a first diode, and a second switch in anti-parallel with a second diode. The first switch and first diode are connected in series with the second switch and the second diode, and the first and second switches are connected in opposing directions, to form a switched snubber.

Abstract: A method and apparatus for welding with an engine driven inverter power supply includes generating an ac output with an engine and generator. The output is rectified and inverted to provide an ac inverter output. The engine is controlled using feedback indicative of a welding output operating parameter. The feedback may also be taken from the inverter or generator, and the generator may be controlled instead of or in addition to the engine. Engine parameters that may be controlled include engine speed, selecting between an idle speed and a run speed, a throttle position, a fuel pump, an injection timer, a fuel to air ratio, fuel consumption and ignition timing. Another aspect of the invention is having the feedback be responsive to one or more of the welding current, welding voltage, welding power, or functions thereof. The feedback may be responsive to the current, voltage, power, ripple and functions thereof.

Abstract: A welding power supply that includes a series resonant converter, including at least one switch and at least one capacitor is disclosed. The converter includes a switching circuit including an enable input. A voltage sensing circuit that determines the earliest safe switching time of the switch is provided. The safe switching time is the time that will prevent a peak voltage on the capacitor from exceeding a predetermined threshold for a next cycle of the converter. The voltage sensing circuit provides an enable signal to the enable input when the earliest switching time has passed, to enable the switching circuit. A pair of welding output terminals connected to the series resonant converter receives the output. A controller including a curve shaper, for providing a constant current output in the welding range is also disclosed. The controller also provides an adaptive hot start that provides varying amounts of energy in response to the welders skill.

Abstract: A short circuit arc welding system is disclosed. The control scheme uses a current command signal to drive the output current. The command signal is comprised of a long-term current command that sets the long-term current command level and a real-time or short-by-short current command. Arc voltage feedback is used to determine if the desired arc length is present and to adjust the long-term command. The short-by-short current command is derived from real-time arc current feedback and is used to control the burn-off rate by an instantaneous, or short-by-short, adjustment of the current command. A function of the time derivative of arc power, less the time derivative of arc current, is used to detect, in real time, when the short is about to clear. A stop algorithm is employed that monitors the arc on a short-by-short basis. When the process is ending a very low current level is provided to avoid forming a ball.

Abstract: A welding machine that includes a power supply having at least one control input is described. The power supply is capable of providing an electrode positive and an electrode negative output. Also, the magnitude and balance of the output is controllable. The machine includes a controller that controls the power supply. If the user selects an electrode negative output the controller causes the output to be electrode positive at at least a first magnitude for a predetermined period of time at the start of the welding process. Then, the controller causes the output to be electrode negative at a magnitude equal to or greater than a second magnitude. Thereafter, the controller causes the output to be a user selected magnitude. If the user selects an ac mode, the electrode positive portion of the output is not constantly responsive to at least one of the user selected frequency and the user selected balance.

Abstract: A system for monitoring a person in a secured zone is disclosed. One or more transmitters transmit a first signal into the zone. The person wears a tag that receives the first signal. The tag transmits a second signal that is responsive to the first signal. A receiver receives the second signal and provides a third signal responsive to the first signal. A controller is connected to the receiver and includes a discrimination circuit that determines if the third signal is responsive to the first signal. The controller provides an alarm signal if responsiveness is found. The responsiveness may be a constant phase relationship, and data may be transmitted by the tag at a frequency derived from the first frequency. A three loop antenna, with each loop disposed in a unique plane is described. Each unique plane is substantially perpendicular to the other unique planes, in another embodiment. The tag includes a band removal circuit that senses the skin resistivity of the patient in another embodiment.

Abstract: A welding cable designed to work with a welding system that does not have a pull-type torch is disclosed. The cable includes an electrode lead and an arc voltage sense lead. An insulating jacket is disposed about the electrode lead. The arc voltage sense lead is physically attached to the insulating jacket, along at least a substantial portion of the insulating jacket. The torch lead is preferably fixedly attached to the torch. The sense lead is connected to a controller. The sense lead may be disposed inside or attached outside the insulating jacket. The arc voltage sense lead may be attached to the electrode lead, rather than the torch itself.

Abstract: An plasma cutter, including a power supply, a cutting torch (with a nozzle), a source of air and a valve, is disclosed. The cutting torch is connected to the two power source outputs (cathode and anode). Air is supplied to the nozzle through the valve from the air supply. In one position the valve allows air to flow from the air source to the nozzle. In a second position the valve prevents air from flowing from the air supply to the nozzle and also vents the nozzle and torch. The torch has a movable electrode and the nozzle is in a fixed position. The nozzle and electrode are each electrically connected to a different one of the power outputs. The electrode is biased (preferably by a spring) to be in contact with the nozzle. However, air flowing into the torch and electrode overcomes the bias and moves the electrode away from the nozzle. If the arc is absent and the user desires current, then the valve is moved to prevent air from flowing into the torch and to vent the torch.

Abstract: A power supply, such as a plasma cutting power supply or a welding power supply, that provides an output to a pair of output terminals is disclosed. The power supply includes a source of voltage and a plurality of choppers. The choppers are connected in parallel between the voltage source output terminals. A controller controls the choppers so that they are out-of-phase with respect to each of the other of the plurality of choppers. The choppers preferably include a freewheeling diode, an inductor and a switch. The number of choppers is approximately equal to the ratio of the open circuit voltage to the output load voltage.

Abstract: A system and method for inductively heating a workpiece includes a controller and a plurality of power supplies that receive and send signals to the controller. Induction heads receive power from the power supplies. The induction heads may be aligned with adjacent segments of the workpiece, and can span the perimeter of the workpiece. The gap between adjacent induction heads is less than one half the size of the adjacent induction heads, and preferably the induction heads abut or substantially abut. Each of the power supplies include feedback for controlling the power delivered to the segments of the workpiece. In alternative embodiments the feedback may be based on the current or power provided to the induction heads, or the power provided to the workpiece.

Abstract: A method and apparatus for stopping a welding process includes monitoring the status of the arc. The output current is commanded to a level sufficient to clear a short if a short circuit forms when the process is stopping. A low current level is commanded after the short has cleared. The low current level is sufficiently low to prevent the forming of a large ball. This is repeated until a short does not form. The wire feed speed is monitored, and the stopping process begins when the wire feed speed drops below a threshold. The stopping process is performed with, a MIG process, a pulsed spray process, and a short circuit transfer welding process. The arc voltage is monitored to determine the status of the arc. The motor is commanded to stop in response to receiving a user provided stop command, and the braking of the motor is controlled. At least one output parameter may be reduced before the threshold is reached, but after receiving the stop signal in another alternative embodiment.

Abstract: A method and apparatus for providing a welding output is disclosed. The apparatus includes a an ac generator having a field winding, a welding output winding and an electronic field controller connected to the field winding. The controller receives a current feedback signal and a voltage feedback signal, and shapes the output curve in response to the desired output command signals. According to one embodiment the controller also receives a field current feedback signal. The controller may shape the output curves to emulate a DC generator, for example by causing the welding output V-A curves to have multiple breakpoints, and/or a substantially preset slope over a welding range wherein the preset slope does not vary over the output current range of the power supply. Also, the slope of the V-A output curve below the welding range may be different than the slope in the welding range.

Abstract: A method and apparatus for providing a welding current is disclosed. The power source is capable of receiving any input voltage over a wide range of input voltages and includes an input rectifier that rectifies the ac input into a dc signal. A dc voltage stage converts the dc signal to a desired dc voltage and an inverter inverts the dc signal into a second ac signal. An output transformer receives the second ac signal and provides a third ac signal that has a current magnitude suitable for welding. The welding current may be rectified and smoothed by an output by an output inductor and an output rectifier. A controller provides control signals to the inverter and an auxiliary power controller that can receive a range of input voltages and provide a control power signal to the controller.

Abstract: A welding machine with a wire feeder and a controller is disclosed. The wire feeder includes a wire feed motor with a motor speed input. The controller is coupled to the motor speed control input. A user selectable wire feed speed input is also connected to the controller. The controller has an input circuit coupled with a non-linear stage such that the relationship between the user selectable wire feed speed input and the actual wire feed speed is not linear. The selectable input may be a potentiometer mounted on a front panel as the user selectable wire feed speed input. The non-linearity may be continuous or two discrete gains.

Abstract: A method and apparatus for welding power includes an input rectifier, a pre-regulator, a convertor, an auxiliary voltage circuit and a controller. The pre-regulator is connected to receive a rectified voltage and provides a dc bus. The convertor converts the bus to a welding output. The auxiliary voltage circuit is connected across the welding output, in parallel with the converter. The controller shuts the converter down in the event an open circuit condition exists at the output, thus providing a safer open circuit voltage.

Abstract: A method and apparatus for welding with an engine driven inverter power supply includes generating an ac output with an engine and generator. The output is rectified and inverted to provide an ac inverter output. The engine is controlled using feedback indicative of a welding output operating parameter. The feedback may also be taken from the inverter or generator, and the generator may be controlled instead of or in addition to the engine. Engine parameters that may be controlled include engine speed, selecting between an idle speed and a run speed, a throttle position, a fuel pump, an injection timer, a fuel to air ratio, fuel consumption and ignition timing. Another aspect of the invention is having the feedback be responsive to one or more of the welding current, welding voltage, welding power, or functions thereof. The feedback may be responsive to the current, voltage, power, ripple and functions thereof.

Abstract: A power supply connector includes a cable receptacle, a front bulkhead insulator and a rear bulkhead insulator. The bulkhead insulators are mounted on the cable receptacle and the power supply chassis. At least one O ring is disposed between the front and rear bulkhead insulators, to seal out water. The front bulkhead insulator includes a stepped portion that mates with a stepped portion on the rear bulkhead insulator. The front bulkhead insulator provides an elongated path from the chassis to the cable receptacle. Also, an O ring is disposed between the cable receptacle and the front bulkhead insulator, to seal out water.

Abstract: A method and apparatus for winding film includes guiding a strip of the film through a winding machine to a rotating spindle. At least one deflector and/or at least one source of air, such as a nozzle, is moved to the path of the film downstream from the spindle, and an airhorn is moved to the spindle. The leading edge of the strip is directed into the airhorn by the deflector and/or air from the nozzle, and then directed by air within the airhorn into its own nip. Finally, the strip is wound about the spindle.

Abstract: A method and apparatus for controlling and maintaining a continuous flow of pilot arc current in a plasma cutting torch includes a pilot circuit, a current sensing circuit, and a control circuit. The control circuit maintains a continuous flow of pilot current through the pilot circuit both before and after a cutting arc has been generated. The control circuit further controls the magnitude of the pilot current in response to the sensing circuit indicating the absence or presence of the cutting arc.