ARCMASTER 401MST POWER SOURCE
Manual 0-5287
2-3 INTRODUCTION
2.08 Duty Cycle
The rated duty cycle of a Welding Power Source, is a statement of the time it may be operated at its rated weld-
ing current output without exceeding the temperature limits of the insulation of the component parts. To explain
the 10 minute duty cycle period the following example is used. Suppose a Welding Power Source is designed to
operate at a 40% duty cycle, 170 amperes at 26.8 volts. This means that it has been designed and built to provide
the rated amperage (170A) for 4 minutes, i.e. arc welding time, out of every 10 minute period (40% of 10 minutes
is 4 minutes). During the other 6 minutes of the 10 minute period the Welding Power Source must idle and be
allowed to cool. The thermal cut out will operate if the duty cycle is exceeded.
Welding Current (AMPS)
Art # A-12450
0
10
20
30
40
50
60
70
80
90
100
0
25
50
75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500
Duty Cycle (PERCENTAGE)
3 phase
1 phase
SAFE OPERATING REGION
Figure 2-1: Duty Cycle
