Lincoln Electric SVM150-A Manual Do Utilizador

Página de 134
GENERAL DESCRIPTION
The Ranger 250 is a gasoline engine-driven welding
power source capable of producing 250 amps at
25VDC at a 100% duty cycle.  The engine is coupled to
a brush-type alternating current generator.  This AC
output is rectified and controlled by Chopper
Technology 
to produce DC current for multi-purpose
welding applications.  The Ranger 250 is also capable
of producing 8,000 watts of AC auxiliary power at 100%
duty cycle.
BATTERY, ENGINE, ROTOR, STA-
TOR AND ENGINE PROTECTION
The 12VDC battery powers the engine starter motor
and also supplies power to the battery PC board and
associated circuitry.  When the engine, which is
mechanically coupled to the rotor, is started and run-
ning, the 12 VDC battery voltage is fed through the bat-
tery board to the rotor field coil via a brush and slip ring
configuration.  This excitation or “flashing” voltage mag-
netizes the rotor lamination.  This rotating magnet
induces a voltage in the stationary windings of the main
alternator stator.  The stator houses a three-phase weld
winding, a 120/240VAC single-phase auxiliary winding,
a 42VAC wire feeder power winding, and a separate
42VAC field feedback winding that is rectified and
serves as a feedback supply for the rotor field winding. 
The engine flywheel alternator supplies charging cur-
rent for the battery circuit.  The oil pressure switch mon-
itors engine oil pressure.  If a low oil pressure condition
should develop, the engine will shut down and the bat-
tery PC board will disable the rotor flashing current.
The idler solenoid is mechanically connected to the
engine’s throttle linkage.  If no welding or auxiliary cur-
rent is being drawn from the Ranger 250, the control
board activates the idler solenoid, which then brings
the engine to a low idle state.  When either welding or
auxiliary current is detected at the toroid current sen-
sor, the control board deactivates the idler solenoid and
the engine returns to high RPM.
THEORY OF OPERATION
E-2
E-2
RANGER 250
FIGURE E.2 – BATTERY, STARTER, ENGINE, ROTOR, STATOR AND ENGINE PROTECTION
NOTE:  Unshaded areas of Block Logic Diagram are the subject of discussion.
ENGINE
CONTROL
BOARD
ROTOR
STATOR
BATTERY
      BOARD
BATTERY
CHOKE
IGBT
MECHANICAL
ROTATION
STARTER
I
D
L
E
R
ARC
CONTROL
OUTPUT
CONTROL
MODE
SELECTOR
POWER MODULE
THREE-PHASE
RECTIFIER
WORK
TERMINAL
ELECTRODE
TERMINAL
+
120VAC
RECEPTACLE
240VAC
RECEPTACLE
SLIP
RINGS
TO 
CONTROL
BOARD
GAS
OIL 
PRESSURE
SWITCH
RUN/STOP
SWITCH
                 FLYWHEEL
                     ALTERNATOR
    
                            TO CONTROL
                             BOARD
              AMPHENOL
4
2
V
A
C
FIELD
WINDING
                                  AUXILIARY 
                                 WINDINGS
                          WIRE FEED
                          PWR WNDG
4
2
V
A
C
2
4
0
V
A
C
1
2
0
V
A
C
W
E
L
D
 
W
I
N
D
I
N
G
+
ANALOG
POWER
BOARD
2
0
V
D
C
4
0
TO
1
0
0
V
D
C
FROM
TOROID
CURRENT 
SENSOR
SHUNT
F
E
E
D
B
A
C
K
SOL
__
__
     REGULATED VOLTAGES
P
W
M
S
I
G
N
A
L
S