PRECHARGE AND PROTECTION
The input voltage is rectified by the input rectifier. The
resultant DC voltage is applied, through the reconnect
switch, to the power board. The power board contains
precharging circuitry for the safe charging of the input
filter capacitors. Once the capacitors are precharged
and balanced the control board activates the CR1+
CR2 input relays. 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 Insulated Gate Bipolar Tran-
sistors supply the main transformer primary winding
with DC current flow. See IGBT Operation discussion
and diagrams in this section.
The power board also monitors the filter capacitors for
voltage balance and under or overvoltage. If either
should occur, the appropriate signal is sent to the con-
trol board to deactivate the CR1+ CR2 input relay. The
machine output will also be disabled.
THEORY OF OPERATION
E-3 E-3
PRO-CUT 80
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NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
