Lincoln Electric PRO-CUT 55 SVM140-A - Manual (Page 28)

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Section E-1 Section E-1
PRO-CUT 55
Theory of Operation ............................................................................................................. Section E
General Description ....................................................................................................................E-2
Input Line Voltage, Contactor and Main Transformer.................................................................E-2
Precharge and Protection ...........................................................................................................E-3
Main Transformer ........................................................................................................................E-4
Output Board and Torch .............................................................................................................E-5
Control and Display Boards........................................................................................................E-6
Protection Circuits ......................................................................................................................E-7
Overload Protection..............................................................................................................E-7
Thermal Protection ...............................................................................................................E-7
Insulated Gate Bipolar Transistor (IGBT) Operation ...................................................................E-8
Pulse Width Modulation (PWM) ..................................................................................................E-9
TABLE OF CONTENTS
-THEORY OF OPERATION SECTION-
INPUT
LINE
SWITCH
INPUT
RECTIFIER
FAN
MOTORS
"A"
L
E
A
D
AUXILIARY
TRANSFORMER
OUTPUT
CONTROL
AIR
PRESSURE
SWITCH
P
R
O
T
E
C
T
O
N
I
SIGNAL
CR 1
DRIVE
SIGNAL
RELAY IGBT
GATE
SIGNALS
R
E
A
D
Y
A
I
R
L
O
W
T
H
E
R
M
A
L
S
A
F
E
Y
T
TRIGGER & SAFETY
ELECTRODE & TRANSFER
CURRENT FEEDBACK
PILOT ENABLE
ELECTRODE SOLENOID ENABLE
AIR SOLENOID ENABLE
AIR
SOLENOID
TRIGGER & SAFETY
E
L
E
C
T
R
O
D
E
S
O
L
E
N
O
I
D
TORCH
CONNECTOR
ELECTRODE
NOZZLE
WORK
R
E
C
O
N
N
E
C
T
S
W
T
C
H
I
POWER BOARD
CR 1
RELAY
IGBT
IGBT
IGBT
IGBT
CAPACITOR
CAPACITOR
CURRENT
TRANSFORMER
CONTROL BOARD
DISPLAY BOARD
18/36VAC
12VAC
24VAC
MAIN
TRANSFORMER OUTPUT BOARD
CHOKE
PILOT
TRANSISTOR
THERMOSTATS
FIGURE E.1 – PRO-CUT 55 BLOCK LOGIC DIAGRAM