Theory of operation, Output control, rectification and feedback – Lincoln Electric IDEALARC SVM136-A User Manual
Page 37
THEORY OF OPERATION
E-3
E-3
IDEALARC CV-400
OUTPUT CONTROL,
RECTIFICATION AND FEEDBACK
The three-phase AC output from the main transformer
secondary is rectified and controlled through the
SCR/diode bridge.
Output current and voltage is
sensed at the shunt and output capacitors, respective-
ly. This feedback information is processed in the con-
trol board. The control board compares the commands
of the output control (or remote control) with the feed-
back information and sends the appropriate gate firing
signals to the SCR/diode bridge.
in this section.
A "dry closure" of leads #2 and #4, either at the termi-
nal strip or the 14 pin amphenol, signals the control
board to apply gate firing signals to the SCR/diode
bridge, which creates a DC voltage at the output of
the bridge assembly. This output is filtered by the
capacitors to reduce the ripple content of the wave-
form. Thus, a smoother DC output is created. The
choke, which is in series with the negative output ter-
minal, stores energy and provides current filtering.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
FIGURE E.3 – OUTPUT CONTROL, RECTIFICATION AND FEEDBACK
FAN
115VAC
42VAC
REMOTE
CONTROL
TO
CONTROL
BOARD
CONTROL BOARD
OUTPUT
CONTROL
CONTROL
TRANSFORMER
POWER
SWITCH
R
E
C
O
N
N
E
C
T
INPUT
CONTACTOR
T
E
R
M
I
N
A
L
S
T
R
I
P
TRANSFORMER
MAIN
SCR
DIODE
HYBRID BRIDGE
/
CAPACITORS
SHUNT
NEGATIVE
OUTPUT
TERMINAL
POSITIVE
OUTPUT
TERMINAL
OUTPUT
G
A
T
E
S
I
G
N
A
L
S
F
E
E
D
B
A
C
K
s
F
E
E
D
B
A
C
K
14 PIN AMPHENOL