Abstract: Electric arc welder (10) performs a given weld process with selected current waveform performed between electrode (24) and workpiece (26). Welder (10) includes a controller with a digital processor (30), sensor (44) for reading instantaneous weld current, and circuit (56) to convert the instantaneous current into a digital representation of the level of instantaneous weld current. Digital processor (30) has program circuit (64, 66) to periodically read and square the digital representation at a given rate, register (70, 72) for summing a number N of square digital representations to give a summed value, and an algorithm (82, 84, 86, 88) for periodically dividing the summed value by the number N to provide a quotient and then taking the square root of said quotient to thereby digitally construct rms signal (40) representing the root mean square of the weld current.

Abstract: Electric arc welder (10) performs a given weld process with selected current waveform performed between electrode (24) and workpiece (26). Welder (10) includes a controller with a digital processor (30), sensor (44) for reading instantaneous weld current, and circuit (56) to convert the instantaneous current into a digital representation of the level of instantaneous weld current. Digital processor (30) has program circuit (64, 66) to periodically read and square the digital representation at a given rate, register (70, 72) for summing a number N of square digital representations to give a summed value, and an algorithm (82, 84, 86, 88) for periodically dividing the summed value by the number N to provide a quotient and then taking the square root of said quotient to thereby digitally construct rms signal (40) representing the root mean square of the weld current.

Abstract: Electric arc welder (10) performs a given weld process with selected current waveform performed between electrode (24) and workpiece (26). Welder (10) includes a controller with a digital processor (30), sensor (44) for reading instantaneous weld current, and circuit (56) to convert the instantaneous current into a digital representation of the level of instantaneous weld current. Digital processor (30) has program circuit (64, 66) to periodically read and square the digital representation at a given rate, register (70, 72) for summing a number N of square digital representations to give a summed value, and an algorithm (82, 84, 86, 88) for periodically dividing the summed value by the number N to provide a quotient and then taking the square root of said quotient to thereby digitally construct rms signal (40) representing the root mean square of the weld current.

Abstract: Electric arc welder (10) performs a given weld process with selected current waveform performed between electrode (24) and workpiece (26). Welder (10) includes a controller with a digital processor (30), sensor (44) for reading instantaneous weld current, and circuit (56) to convert the instantaneous current into a digital representation of the level of instantaneous weld current. Digital processor (30) has program circuit (64, 66) to periodically read and square the digital representation at a given rate, register (70, 72) for summing a number N of square digital representations to give a summed value, and an algorithm (82, 84, 86, 88) for periodically dividing the summed value by the number N to provide a quotient and then taking the square root of said quotient to thereby digitally construct rms signal (40) representing the root mean square of the weld current.