Theory of operation, General description, Input line voltage, contactor and main transformer – Lincoln Electric PRO-CUT 55 SVM140-A User Manual
Page 29
GENERAL DESCRIPTION
The Pro-Cut 55 is a constant current, continuous con-
trol plasma cutting power source. The inverter based
power supply design is controlled by a microprocessor
control board. The control system has a safety mech-
anism to insure that the nozzle and electrode are in
place before cutting or gouging. The Pro-Cut 55 initi-
ates the plasma arc with a simple, yet reliable, touch
start mechanism. This system eliminates many of the
problems associated with hi-frequency type start sys-
tems.
INPUT LINE VOLTAGE,
CONTACTOR AND MAIN
TRANSFORMER
The single-phase or three-phase input power of 200-
230 or 400 to 460 volts AC is connected to the
machine, via an input line cord, to a switch located on
the front panel.
A reconnect panel and voltage range switch allow the
user to configure the machine for either a low or high
input voltage and also connect the auxiliary trans-
former for the appropriate input voltage.
The auxiliary transformer develops the appropriate AC
voltages to operate the cooling fans, the control board
and the plasma output board.
THEORY OF OPERATION
E-2
E-2
PRO-CUT 55
FIGURE E.2 – INPUT LINE VOLTAGE
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
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