Input Line Voltage, Auxiliary Transformer And Precharge; Input Voltage And Precharge; Theory Of Operation; General Description - Lincoln Electric INVERTEC V350-PRO Service Manual

E-2
Input switch
Rectifier
Auxiliary
Transformer
115VAC, 42VAC
24VAC
28VAC
14 Pin
Amphenol
6 Pin
Amphenol

GENERAL DESCRIPTION

The Invertec V350-Pro is an inverter based welding
power source that offers multi mode constant voltage
(CV) and constant current (CC) welding and is rated at
350 amps 34VDC at a 60% duty cycle. The Invertec
V350-Pro is available in a construction version (no wire
feeder connection or auxiliary power ), a factory ver-
sion that includes a wire feeder connection and relat-
ed power, an advanced process version and a rack
version.
INPUT LINE VOLTAGE, AUXILIARY
TRANSFORMER, & PRECHARGE
The Invertec V350-Pro can be connected for a variety
of three-phase or single-phase input voltages. The ini-
tial power is applied to the V350 through a line switch
located on the front of the machine. Two phases of the
input voltage are applied to the auxiliary transformer.
The auxiliary transformer develops four different sec-
ondary voltages. The 115VAC is used to power the fan
motor and also is applied to the 14 pin amphenol type
connector for wirefeeder operation. The 24VAC and
42VAC voltages are also applied to the 14 pin amphe-
nol type connector to power wirefeeders. The 28VAC
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.

THEORY OF OPERATION

FIGURE E.2 – INPUT VOLTAGE AND PRECHARGE
Main Switch Board
Input
Reconnect
Switch
Fan
115VAC Fan Supply
V/F Capacitor Feedback (2)
Machine Control Supply
+15VDC, -15VDC, +5VDC
Power
SPI Supply +15VDC +5VDC
Board
40VDC
RS232 Supply +5VDC
Remote Control & Trigger
Output
Control
Output
Potentiometer
Primary
Current
Sensor
Primary
Current
Sensor
Primary Current Feedback
Input Relay Control
Soft Start Control
Control Board
SPI Communications & +15VDC, +5VDC Supply
Mode
Remote
Panel
Board
(Not used if APP
is in place)
Weld
Optional Solenoid
Terminals
is rectified and the resultant 40VDC is applied to the
power board.
The input voltage is rectified by the input rectifier and
the resultant DC voltage is applied to the switch board
through the reconnect switch assembly located at the
rear of the machine. The reconnect switch connect the
two pairs of input capacitors either in a parallel (lower
voltage) or series (higher voltage) configuration to
accommodate the applied input voltage.
During the precharge time the DC input voltage is
applied to the input capacitors through a current limit-
ing circuit. The input capacitors are charged slowly
and current limited. A voltage to frequency converter
circuit located on the switch board monitors the
capacitor voltages. This signal is coupled to the con-
trol board (measure frequency, not voltage to check
signal). When the input capacitors have charged to an
acceptable level, the control board energizes the input
relays, that are located on the switch board, making all
of the input power, without current limiting, available
to the input capacitors.
under or over voltage the control board will de-ener-
gize the input relays and the V350 output will be dis-
abled. Other possible faults may also cause the input
relays to drop out.
V350-PRO
To Control
Board
Positive
Output
Terminal
Choke
Negative
Output
Terminal
RS232
Advanced
Display
Process
Panel
Panel
If the capacitors become
E-2