Lincoln Electric 11141 Service Manual page 39

TABLE OF CONTENTS-THEORY OF OPERATION SECTION
E-1
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .E-1
General Description ...................................................................................................................................E-2
Input Line Voltage, Auxiliary Transformer and Precharge .........................................................................E-2
Switch Board and Main Transformer .........................................................................................................E-3
DC Bus Board, Power board and Control Board.......................................................................................E-4
Output Rectifier and Choke .......................................................................................................................E-5
Thermal Protection ....................................................................................................................................E-6
Protective Circuits ......................................................................................................................................E-6
Over current Protection .......................................................................................................................E-6
Under/Over Voltage Protection............................................................................................................E-6
Insulated Gate Bipolar Transistor (IGBT) Operation..................................................................................E-7
Pulse Width Modulation .............................................................................................................................E-8
Minimum/Maximum Output..................................................................................................................E-8
Input
Input switch
Rectifier
Auxiliary
{
P
Transformer
o 220 VAC
w
e
r
W
a
v
e
42VAC
4
220
0
5
Receptacle
o
n DC
l
Bus
y
Board
FIGURE E.1 BLOCK LOGIC DIAGRAM
Main Switch Board
Reconnect
Switch
Fan
115VAC Fan Supply
V/F Capacitor Feedback (2)
Machine Control Supply
40VDC
+15VDC, -15VDC, +5VDC
Power
Board
RS232 Supply +5VDC
Can Supply +5VDC
40VDC
POWER WAVE
Primary
Current
Sensor
Primary
Current
Sensor
Primary Current Feedback(2)
Input Relay Control
Soft Start Control
Control Board
Arc
Electrode
Link Sense
Wire
Feeder
Recp.
Thermostats
2
To
Feeder
® 355M/405M
E-1
To Control
Board
Positive
Output
Terminal
Choke
Negative
Output
Terminal
Yellow
Thermal
LED
Status
Red/Green
LED
21 Lead
Voltage
R232
Sense
Connector
Recp.