Theory of operation, Constant voltage output, E-3 wire-matic 255 – Lincoln Electric WIRE-MATIC 255 SVM 119-A Manuel d'utilisation
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E-3
THEORY OF OPERATION
E-3
WIRE-MATIC 255
CONSTANT VOLTAGE OUTPUT
The controlled DC output from the SCR rectifier
assembly is filtered by the capacitor bank resulting is a
constant voltage DC output. Since the output choke is
in series with the positive leg of the rectifier and also in
series with the gun and welding load, a filtered con-
stant voltage output is applied to the output terminals
of the machine.
Figure E.4 - Constant Voltage Output.
CONSTANT VOLTAGE OUTPUT
LINE
SWITCH
MAIN
TRANSFORMER
RECONNECT
FAN
MOTORS
SCR
RECTIFIER
C
A
P
A
C
I
T
O
R
S
SHUNT
CHOKE
WIRE
DRIVE
MOTOR
TACH
POSITIVE
TERMINAL
NEGATIVE
TERMINAL
GAS
SOLENOID
WIRE
SPEED
ARC
VOLTAGE
CONTROL BOARD
FEEDBACK
GUN TRIGGER AND THUMB SWITCH
F
E
E
D
B
A
C
K
G
A
T
E
I
G
N
S
A
L
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion