PRECHARGE (SOFT START)
The Protection Board contains a “soft Start” circuit,
which is powered by the Auxiliary Transformer. During
precharge or “soft start” only two phases of the input
power, with current limiting, are connected to the input
rectifier. This AC input voltage is rectified, and the DC
voltage is applied through the Reconnect Switches to
the input capacitors located on the Switch Boards.
The Protection Board monitors the voltage across the
capacitors. When the capacitors have charged to an
acceptable level, the Protection Board energizes the
Main Input Contactor, making all three phases of input
power available to the input capacitors. At this point
the Power Wave is in the “Run Mode” of operation. If
the capacitors become under- or overvoltaged, the
Protection Board will de-energize the Main Input
Contactor, and the machine output will be disabled.
THEORY OF OPERATION
E-3 E-3
POWER WAVE 450
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FIGURE E.3 – PRECHARGE CIRCUIT
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
AUX.
