3-4.
Duty cycle & Over heat
Strictly to apply the maximum working time (see technical specifications). If you go
beyond this period, the machine suddenly stop. This is possible due to the internal over
-
load because the machine overheats. In this case, it is not necessary to turn off the
machine, the fan should be working to reduce the temperature. Usually within 5-10
minutes the machine working again.
I
（
A
）
0
100
％
25%
80
X
160
The letter “X” stands for duty cycle,
which is defined as the proportion
of the time that a machine can
work continuously within a certain
time (10 minutes). The rated duty
cycle means the proportion of the
time that a machine can work
continuously within 10 minutes
when it outputs the rated welding
current.
66
44
20
0
600
I
2
（
A
）
U
2
（
V
）
3-5.
Volt-Ampere Characteristic
A Heavy Duty welders have excellent volt-ampere characteristic, seeing the following
graph.
In MMA welding, the relation between the rated loading voltage U
2
and welding cur
-
rent I
2
is as follows:
When I
2
≤600A then U
2
=20+0.04 I
2
(V) When I
2
>600A thenU
2
=44(V)
The relation between duty-cycle
and welding current
EN
29
