Lincoln Electric IDEALARC CV-305 - Manual (Page 29)

THEORY OF OPERATION E-3 E-3
IDEALARC® CV-305
OUTPUT RECTIFICATION, FILTERING,
CONTROL AND FEEDBACK
The main transformer secondary windings are con-
nected to an SCR/Diode hybrid rectifier bridge. This
three phase AC output from the main transformer sec-
ondary is rectified and controlled through the rectifier
bridge (see
SCR Operation). Output current and volt-
age are sensed at the shunt and the output terminals
and fed back to the control board. This feedback infor-
mation is processed in the control board. The control
board compares the commands of the output control
potentiometer (or remote control) with the feedback
information and sends the appropriate gate firing sig-
nals to the rectifier bridge. The control board also sup-
plies power and signals to the meter board.
The capacitors and the output choke provide the filter-
ing for the controlled DC output of the CV 305 machine.
The choke is tapped for supplying either a soft (high
inductance) or a more harsh (low inductance) welding
arc.
FIGURE E.3 — Output Rectification, Filtering, Control Feedback, & Power Factor Enhancement
A power factor correcting choke added between the
Output Rectifier ant the Capacitor Bank enables the
CV 305 to provide 20% greater efficiency as compared
to the CV 300.
INPUT
LINE
SWITCH
MAIN
TRANSFORMER
RECONNECT
PANEL
FAN
MOTOR
OUTPUT
RECTIFIER
+
SHUNT
CHOKE
OUTPUT
TERMINALS
CONTROL BOARD
F
E
E
D
B
A
C
K
G
A
T
E
S
METER
OUTPUT
CONTROL
14 PIN
AMPHENOL
TRIGGER AND REMOTE
12VAC
12VAC
4
2
V
A
C
-
CAPACITORS
+
F
E
E
D
B
A
C
K
-
-
115VAC
POWER FACTOR
ENHANCEMENT
CHOKE
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
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