16
•
2.5. Working Principle
The working principle of ARC series of welding machines is shown in the following figure.
Single-phase 110V/220V line frequency AC is rectified into DC, then is converted to medium
frequency AC by inverter device (IGBT), after reducing voltage by medium transformer (the main
transformer) and rectified by medium frequency rectifier (fast recovery diode), and is outputted
by inductance filtering. The circuit adopts current feedback control technology to insure current
output stability. Meanwhile, the welding current parameters can be adjusted continuously and
steplessly to meet with the requirements of welding craft.
•
2.6. Volt-Ampere Characteristic
ARC series of welding machines has excellent volt-ampere characteristic. Referring to the
following graph. In MMA welding, the relation between the rated loading voltage U
2
and welding
current I
2
is as follows:
When I
2
≤600ª, U
2
=20+0.04 I
2
(V); When I
2
>600ª, U
2
=44(V).
Rectify
Inverter
Medium
frequency
transformer
Medium
frequency
rectify
Hall device
Current positive-
feedback control
Three-phase, AC
DC
AC
DC
380V
,
50Hz
AC
DC
66
44
20
0
600
I
2
(
A
)
U
2
(
V
)
Working
point
Volt-ampere characteristic
The relation of the rated loading
voltage&welding current
Single-phase, AC
110V/220V
50/60Hz