Abstract: A power supply, for a plasma cutter or a plasma arc welder, having a variable switching frequency and method of operating the power supply is generally disclosed. The power supply includes a switch for setting the switching frequency and a chopper control circuit for determining current output from the power supply, determining an operating frequency based on the determined current output and setting the switching frequency based on the determined operating frequency.

Abstract: A power supply, for a plasma cutter or a plasma arc welder, having a variable switching frequency and method of operating the power supply is generally disclosed. The power supply includes a switch for setting the switching frequency and a chopper control circuit for determining current output from the power supply, determining an operating frequency based on the determined current output and setting the switching frequency based on the determined operating frequency.

Abstract: A power supply, for a plasma cutter or a plasma arc welder, having a variable switching frequency and method of operating the power supply is generally disclosed. The power supply includes a switch for setting the switching frequency and a chopper control circuit for determining current output from the power supply, determining an operating frequency based on the determined current output and setting the switching frequency based on the determined operating frequency.

Abstract: A metering system and associated method for supplying gas to a torch are provided. The metering system includes a controller that is configured to adjust a pressure regulator according to the pressure and flow rate of the gas delivered to the torch. For example, the torch can be a plasma arc torch that has an electrode positioned in a nozzle and operates in a working mode by providing an arc from the electrode to a workpiece. In a first mode of operation, the metering system can provide a gas to the torch by adjusting the pressure regulator according to the pressure downstream of the pressure regulator. In a second mode of operation, the metering system can provide adjust the pressure regulator according to the flow rate of the gas through a flow transducer in series with the pressure regulator.

Abstract: A metering system and associated method for supplying gas to a torch are provided. The metering system includes a controller that is configured to adjust a pressure regulator according to the pressure and flow rate of the gas delivered to the torch. For example, the torch can be a plasma arc torch that has an electrode positioned in a nozzle and operates in a working mode by providing an arc from the electrode to a workpiece. In a first mode of operation, the metering system can provide a gas to the torch by adjusting the pressure regulator according to the pressure downstream of the pressure regulator. In a second mode of operation, the metering system can provide adjust the pressure regulator according to the flow rate of the gas through a flow transducer in series with the pressure regulator.

Abstract: A power source for a plasma cutting tool includes first and second power switching circuits and a controller. Each power switching circuit includes a switch for switching electrical power to a respective output, and the outputs of the power switching circuits are connected in parallel. The controller controls the switches in response to a desired output for the power source. The controller also includes a synchronizer for synchronizing the first and second switches so that both of the switches switch electrical power at a common duty cycle. The synchronizer can also maintain a 180 degree phase relationship between switching of the first and second switches. Related methods are also discussed.

Abstract: A power source for a welding or cutting system is provided which preferably includes a power switching circuit, a switching cessation detector, and overshoot reducing means. The power switching circuit switches electrical power to provide an electrical power output signal of the power source to an electric arc tool operatively coupled thereto. The switching cessation detector is responsive to the power switching circuit. The cessation detector generates a switching cessation signal responsive to detecting electrical power being supplied to an electric arc tool operatively coupled to the power source when the power switching circuit ceases switching. The overshoot reducing means is responsive to the switching cessation signal and reduces excess current output from the power switching circuit upon resumption of switching. Related methods are also discussed.

Abstract: A cutting and welding system is disclosed which includes a metering system for controlling at a location remote from the plasma arc torch the amount of gas and water fed to the plasma arc torch. The system includes at least one torch having an electrode, a nozzle assembly positioned adjacent the discharge end of the electrode, and structure for generating a flow of gas between the electrode and the nozzle assembly to create plasma flow through the bore to a workpiece. A gas line communicates with a source of gas and the plasma arc torch for supplying gas to the torch. A plurality of metering orifices are positioned within the gas flow line in a parallel bank with each other so that the gas may flow through each of the metering orifices. Each metering orifice has a predetermined diameter opening. A gas control valve is mounted adjacent each of the metering orifices within the gas flow line on the upstream side toward the supply of gas.

Abstract: A regulated constant current is supplied to a welding load by an SCR power supply having an SCR rectifier network interposed in series between the welding load and applied input power with the SCR power supply comprising means for generating a first feedback signal proportional to arc current which substantially coincides in time and phase with the arc current; means for generating a second feedback signal proportional to arc current which is substantially nonresponsive to the arc current fundamental ripple frequency, means for weighing the first and second feedback signals in a predetermined proportion to establish an error feedback control signal and means for applying trigger signals to the SCR rectifier network in timed synchronism with the input AC power line as a function of the error feedback control signal.