Theory Of Operation; General Description; Battery, Engine, Rotor, Stator And Engine Protection - Lincoln Electric RANGER 250 SVM150-A Service Manual

E-2
FIGURE E.2 – BATTERY, STARTER, ENGINE, ROTOR, STATOR AND ENGINE PROTECTION
GAS
ENGINE
STARTER
FLYWHEEL
ALTERNATOR
OIL
PRESSURE
SWITCH
SOL
I
D
BATTERY
L
RUN/STOP
E
SWITCH
R
TO CONTROL
BATTERY
BOARD

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-
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.

THEORY OF OPERATION

E
W
MECHANICAL
ROTATION
SLIP
RINGS
STATOR
FIELD
WINDING
4
2
V
2
A
4
C
0
V
A
BOARD
C
240VAC
RECEPTACLE
RANGER 250
THREE-PHASE
RECTIFIER
+
4
0
POWER MODULE
D W
TO
L I
1
N
0
D
0
I
N V
G
D
C
ANALOG
POWER
ROTOR
BOARD
REGULATED VOLTAGES
AUXILIARY WIRE FEED
WINDINGS PWR WNDG
4
2
V
A
1
C
2
0
AMPHENOL
V
A
C
120VAC
RECEPTACLE
netizes the rotor lamination.
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.
WORK
TERMINAL
TO
CONTROL
BOARD
ELECTRODE
TERMINAL
IGBT
CHOKE
SHUNT
F
E
E
2 S
D
FROM
0 I
P
B
TOROID
G
W
A
CURRENT
V N
M
C
SENSOR
D A
K
C L
S
CONTROL
BOARD
OUTPUT MODE
ARC
CONTROL CONTROL SELECTOR
This rotating magnet
E-2
__ __
+