Welder Duty Cycle
Allowable welder duty cycle at a target amperage from the rated amperage and duty cycle.
Example
You enter
- Rated amperage A1 (A) 250
- Rated duty cycle (%) 60
- Target amperage A2 (A) 300
You get
- Allowable duty at target 41.6667
- Minutes on 4.16667
- Max continuous (100%) amperage 193.6 A
Checked against published worked examples from: NEMA EW-1 inverse-square duty-cycle relation.
Details, formula, and sources
ScopeDC2 = DC1 x (A1/A2)^2 (capped at 100%), minutes on per 10-minute window, and the maximum continuous amperage A1 x sqrt(DC1/100) (first-principles I-squared heating, NEMA EW-1).
Formula or tableDC2 = DC1 x (A1/A2)^2 (capped at 100%); minutes-on per 10-min window = DC2 x 10; maximum continuous amperage A100 = A1 x sqrt(DC1/100).
Source and editionThe inverse-square duty-cycle relation (NEMA EW-1 arc-welding power-source convention), by name; first-principles I^2-heating, public domain.
Free accessFirst-principles resistive heating, public; duty cycle is measured over a 10-minute window.
What governsEstimate. AHJ and licensed professional govern.
API field namesrated_amps, rated_duty_pct, target_amps, duty_at_target_pct, minutes_on, max_continuous_amps
- Duty-cycle window the rated duty cycle is over a standard 10-minute window (NEMA EW-1)NEMA EW-1