Control circuits, Output rectification, contactor & control boards, Theory of operation – Lincoln Electric POWER MIG SVM157-A User Manual
Page 31: Output rectification, contactor and control board, Power mig 200
THEORY OF OPERATION
E-3
E-3
POWER MIG 200
OUTPUT RECTIFICATION,
CONTACTOR AND CONTROL
BOARD
The AC voltage developed on the secondary
winding is applied, through the selector switch
and output contactor, to the output rectifier
bridge. This DC welding voltage is filtered by
the output capacitors and applied to the output
terminals and welding gun. Since the output
choke is in series with the positive leg of the
output rectifier and also in series with the gun
and welding load, a filtered constant voltage
output is applied to the output terminals of the
machine.
FIGURE E.3 – CONTROL CIRCUITS.
NOTE: Unshaded areas of block logic diagrams are the subject of discussion.
LINE
SWITCH
RECONNECT
PANEL
FAN
MOTOR
RECTIFIER
DIODE
BRIDGE
CONTROL BOARD
GAS
SOLENOID
WIRE
SPEED
CONTROL
WIRE
DRIVE
MOTOR
TACH
FEEDBACK
GUN TRIGGER
+
-
OUTPUT DIODE
BRIDGE
+
-
NEGATIVE
TERMINAL
CONTACTOR
CONT
ACT
OR
CONTROL
TAP SELECTOR
SWITCH
OUTPUT
CHOKE
POSITIVE
TERMINAL
TRANSFORMER
THERMOSTAT
OUTPUT BRIDGE
THERMOSTAT
28 V
AC
MAIN
TRANSFORMER
OUTPUT
CAPACITORS
GUN
ASSEMBLY