Lincoln Electric RANGER 305 D Service Manual page 53

RANGER 305D
ENGINE
PROTECTION
LIGHT
ENGINE
PROTECTION
CIRCUIT
FUEL
PUMP
FUEL
SOLENIOD
HOLD COIL
PULL COIL
START
BUTTON
GLOW
PLUG
BUTTON
12V.
BATTERY
RUN
STOP
SWITCH
GENER TING POWER
FL SHING:
The battery supplies 12VDC power to the control PC board. When the
engine protection light shuts off, the control board allows the 12VDC
"flashing" voltage to be applied to the now rotating generator field
winding, first passed through a current limiting resistor, then through
the brushes and slip rings to frame ground.
BUILDING OUTPUT:
The flashing current produces a weak magnetic field in the rotor. This
rotating magnetic field begins to generate AC output from all of the
stator windings. Output form the 42 VAC exciter winding is rectified
by a diode bridge, then filtered by a capacitor and fed back into the
rotating field winding, through the brushes, making the magnetic field
stronger. This stronger magnetic field then produces higher voltage
from the stator windings, which feeds back to the rotor, making its
magnetic field even stronger.
This process of strengthening the magnetic field through feedback
from the output continues to increase the output of the main
generator until the design voltage is reached. The output of the
machine depends on engine RPM and rotor current.
The field voltage is now considerably higher than the flashing voltage
that was used to start the generating process. Circuitry in the control
PC board blocks that higher field voltage from intruding into the
12VDC battery system.
FIGURE E.4 – GENER TING POWER & OUTPUT
CHARGING
SYSTEM LIGHT
(CODE 10926 ONLY)
ENGINE
GLOW
ENGINE
SENSORS
PLUGS
ALTERNATOR
ENGINE
STARTER
IDLE
SOLENOID
PULL HOLD
COIL COIL
FLASHING
PULL COIL
PC BOARD
E 4
MODULE
WELD
WINDING
ROTOR
STATOR
42 VAC
EXCIT ER 120/240 VAC
AUX.WINDING WINDING
WINDING
CURRENT
SENSOR
14
240
PIN
VAC 120
AMPHENALS 6
vac
RECEPTACLES
PIN
C OUTPUT:
The generator is now producing sufficient AC power from all four of
the windings. These windings consist of 60 to 65 VAC three phase
weld winding, a 120/240 VAC auxiliary power winding, a 42 VAC
exciter winding, and a 42 VAC wire feeder power winding.
DC OUTPUT:
The output from the three phase weld winding is converted to DC by a
three phase output rectifier then filtered by four large capacitors
located on the power module assembly. This produces about 90VDC
power that supplies the IGBTs on the power module and the weld
control PC board.
THEORY OF OPERATION
SHUNT
IGBTs
POWER
CHOKE
AMP
DISPLAY
WELD CONTROL
VOLT
P.C. BOARD
DISPLAY
IDLE
SWITCH
OUTPUT
MODE WELDING
CONTROL
SWITCH
TERMINAL
SWITCH
ARC
CONTROL
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