THEORY OF OPERATION
E-4 E-4
V205-T AC/DC
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FIGURE E.4 – MAIN TRANSFORMER, OUTPUT DIODE MODULE & CLAMPING BOARD,
OUTPUT TRANSISTOR MODULE & SUPERIMPOSITION BOARD
MAIN TRANSFORMER
The 100KHZ output of the Main IGBT Inverter Board is
coupled, through a DC Blocking Capacitor Board, to
the primary of the Main Transformer. The transformer
reduces the high voltage (low current) input applied to
the primary winding and through transformer action
develops a lower secondary voltage capable of high
output currents.
OUTPUT MODULE AND CLAMPING
BOARD
The AC output of the Main Transformer is applied to
the Output Modules for full wave rectification. The
Clamping Diodes function as a filter eliminating any
pulsed over-voltages that may be present at the
Output Modules. The Clamping Board protects the
Output Modules from damage due to higher than nor-
mal voltage spikes.
OUTPUT MODULE TRANSISTOR
BOARD
This module produces the AC waveforms and fre-
quencies. It receives command signals from the
Superimposition Board. Depending on which of the
two IGBTs is active at any given moment the welding
output of the machine can be either positive or nega-
tive AC or DC.
SUPERIMPOSITION BOARD
The Super Imposition Board receives signals from the
Control/Display Board to control the status of the sec-
ondary inverter portion of the V205T machine. This
board also generates voltage pulses at about +/-
200VDC that facilitate the re-striking of the arc when
the TIG AC welding current is being utilized. The
Superimposition Board internally generates the auxil-
iary power supply for the isolated piloting of the power
elements (IGBTs) for the Output Module Transistor
Board. The Superimposition Board plugs directly into
the Bus Board.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
