CONTROL BOARD
The Control Board performs the primary interfacing
functions to establish and maintain output control of the
Power Wave 455R machine. The function generator
and weld files exist within the Control Board hardware
and software. Digital command signals and feedback
information is received and processed at the Control
Board. Software within the Control Board processes
the command and feedback information and sends the
appropriate pulse width modulation (PWM) signals
(see PULSE WIDTH MODULATION in this section) to
the switch board IGBTs. In this manner, the digitally
controlled high-speed welding waveform is created.
The Control Board also monitors and controls the STT
(Surface Tension Transfer) circuitry incorporated in the
Power Wave 455R. STT output currents and arc volt-
ages are monitored, and the appropriated gate firing
signals are applied (or removed) from the STT
Chopper Board and switch boards to create a low spat-
ter, low fume MIG welding process. See GENERAL
DESCRIPTION OF STT (SURFACE TENSION
TRANSFER PROCESS) in this section.
In addition, the Control Board monitors the ther-
mostats, the main transformer primary currents and
input filter capacitor voltages. Depending on the fault
condition, the Control Board will activate the thermal
and/or the status light and will disable or reduce the
machine output. In some conditions the input contac-
tor will be de-energized.
E-7 E-7
THEORY OF OPERATION
POWER WAVE 455M/MSTT
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FIGURE E.6 – CONTROL BOARD
