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INVERTER AND MAIN TRANSFORMER
INVERTER AND MAIN
TRANSFORMER
When the input filter capacitors are fully charged
they act as power supplies for the IGBT switching
circuit.
The IGBT switch the DC power from the input
capacitors "on and off," thus supplying pulsed DC
current to the main transformer primary windings.
The full bridge inverter switching frequency is 25-
30KHz. Current transformer located on the
inverter board monitor the primary current. If the
primary current become abnormally high, the
inverter control circuit will shut off the IGBTs, thus
disabling the machine's output. A thermal
protector is also present, to the inverter heat-sink,
to protect the IGBTs from overheating conditions.
The main transformer insulate the primary circuit
from the secondary circuit; this secondary winding
supplies the welding voltages and the welding
currents. This high current winding is capable of
supplying maximum output current during the
cutting process. An auxiliary main transformer
winding, provides to the output circuit the extra
voltage required when special stick electrodes,
like cellulosic, are used with the machine.
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