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15 The power module
The power module converts 3--phase 400 V to the welding voltage. It consists of a single
forward inverter, operating at a switching frequency of 27 kHz.
The mains rectifier bridge 15BR1, the IGBT transistors 15Q1 and 15Q2 and the diode
modules 15D1 and 15D2 are all mounted on a heat sink. Circuit board 15AP1 links them
together. It also carries a smaller circuit board, 15AP2, which provides the functions for the
gate drivers and overvoltage and undervoltage protection.
Block diagram of the power module
If the IGBT transistors 15Q1 and 15Q2, or circuit boards 15AP1, 15AP2 or 20AP1, are
replaced, the gate pulse waveforms must be checked afterwards and the machine must be
soft--started. See page 60.
See the instructions on page 59 concerning mounting of the components on the heat sink
(15Q1, 15Q2, 15BR1, 15D1 and 15D2).
WARNING!
The power module is live at mains voltage.
0 V in the power module is connected to mains voltage.
S0740 800 191/E080229/P78
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ct32_15
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