THEORY OF OPERATION
Page 2-2
MAX42 Service Manual
GENERAL
The theory of operation describes the basic operation of the 208-240 VAC, 1 PH, 60
Hz Power Unit. It is assumed that the technician has a working knowledge of inverter
power supply theory.
PRINCIPLES OF OPERATION
Refer to the following principles and Figure 2-1 to understand how the MAX42 Power
Unit works.
1.
The incoming 1-phase AC power is converted to DC by the input rectifier board.
2.
The DC current is converted back into high frequency AC current (20 Khz) by the
inverter.
3.
The isolation transformer couples the voltage from the inverter to the secondary
rectifier.
4.
The secondary rectifier converts the AC back to DC for the output current to the
torch and to the pilot arc controller. The pilot arc controller provides current
control between the nozzle and electrode.
5.
The feedback loop (control board, modulator board, and current sensor) monitors
the inverter output and controls it by varying the pulse width to the FET packs.
Figure 2-1 MAX42 Power Unit Block Diagram
Primary
Rectifier
Filter
Inverter
Isolation
Transformer
Secondary
Rectifier
Filter
Modulator
Current
Sensor
AC
Input
Power
Torch
DC
AC
DC
Control
Pilot Arc
Controller
Summary of Contents for MAX42
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