THEORY OF OPERATION
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CHOPPER TECHNOLOGY
FUNDAMENTALS
The new era of welding machines such as the Multi- Weld 350 employ a technology whereby a DC source is turned on and off (chopped up) at high speed, then smoothed through an inductor to control an arc.
Hence the name “Chopper.” The biggest advantage of chopper technology is the
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EXTERNAL DC | SOLID STATE | INDUCTOR | ARC | |
SOURCE | SWITCH | AND DIODE | ||
|
ARC
CONTROL
In this system, current from a DC source such as the | in the inductor and the arc can be controlled. The fol- |
lowing diagram depicts the current flow in the system | |
to an inductor. By turning the switch on and off, current | when the switch is open and closed: |
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SWITCH
70-80VDC
DIODE
INDUCTOR
ARC
CURRENT WITH SWITCH OPEN
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CURRENT WITH SWITCH CLOSED
When the switch is closed, current is applied through | varying the ratio of on time versus off time of the switch | |
the inductor to the arc. When the switch opens, current | (Duty Cycle), | the current applied to the arc is con- |
stored in the inductor sustains flow in the arc and | trolled. This | is the basis for Chopper Technology: |
through the diode. The repetition rate of switch closure | Controlling the switch in such a way as to produce | |
is 20Khz, which allows | superior welding. | |
