Firepower MST 220i, Operating Manual

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FIREPOWER MST 220i
Manual 0-5343 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 welding
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 oper-
ate at a 20% duty cycle, 210 amperes at 24.5 volts. This means that it has been designed and built to provide the
rated amperage (210A) for 2 minutes, i.e. arc welding time, out of every 10 minute period (20% of 10 minutes is
2 minutes). During the other 8 minutes of the 10 minute period the Welding Power Source must idle and allowed
to cool. The thermal cut out will operate if the duty cycle is exceeded.
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220
FIREPOWER MST 220i
Welding Current (AMPS)
SAFE OPERATING REGION
(MIG, TIG & STICK)
0
0
10
20
30
40
60
70
50
80
100
90
Duty Cycle (PERCENTAGE)
MIG
STICK / TIG
Art # A-12524
Figure 2-2: Firepower MST 220i Duty Cycle on 208/230VAC
Welding Current (AMPS)
Duty Cycle (PERCENTAGE)
Art # A-12525
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
FIREPOWER MST 220i
SAFE OPERATING REGION
(MIG, TIG & STICK)
TIG
STICK
MIG
Figure 2-3: Firepower MST 220i Duty Cycle on 115V AC