PRECHARGE AND PROTECTION
The input voltage is rectified by the input rectifier on
the inverter board. The resultant DC voltage is applied
to the filter capacitors through the automatic
reconnect of the input board. The input board also
contains precharging circuitry for the safe charging of
the input filter capacitors. Once the capacitors are
precharged the input board activates the RL3 input
relay. This connects full input power to the filter
capacitors. When the filter capacitors are fully
charged they act as power supplies for the IGBT
switching circuit. The IGBTs supply the main trans-
former primary winding with DC current flow.
The inverter board also monitors the filter capacitors
for overvoltage. If this occurs, the appropriate signal
is sent to the control board to disable the machines
output and to turn on the Thermal/Voltage Overload
status LED. See IGBT Operation discussion and
diagrams in this section.
THEORY OF OPERATION
E-3 E-3
PRO-CUT 25
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NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
