Theory Of Operation - Lincoln Electric RANGER 305 D Service Manual

RANGER 305D
FIGURE E.3 –ENGINE IDLE SYSTEM, IDLE SWITCH & IDLE SOLENOID
ENGINE
PROTECTION
LIGHT
ENGINE
PROTECTION
CIRCUIT
FUEL
PUMP
FUEL
SOLENIOD
HOLD COIL
PULL COIL
START
BUTTON
GLOW
PLUG
BUTTON
12V.
BATTERY
RUN
STOP
SWITCH
ENGINE IDLE SYSTEM
IDLE SWITCH OPER TION:
When the engine is started it operates at high RPM. If the idle switch
is in the high position the automatic idle system is inactive and
the engine will continue to operate at high RPM.
If the engine is started with the idle switch in the auto position,
or if the idle switch is moved to the auto position while
the engine is running, a 12 second on the control PC board is started. If
there is no significant current flow detected from the weld or auxiliary
outputs during that 12 second time, the idle solenoid will be activated,
dropping the engine RPM to preset low idle speed. If a load is applied
during the 12 second delay, the engine speed will remain high.
While operating at low RPM; if the idle switch is moved to high, or
there is a load detected from either the weld of auxiliary outputs, the
idle solenoid will be deactivated, allowing the engine governor to
increase the RPM to high speed.
When the idle switch is in the "auto" position and the machine is
under load and running at high RPM. If the load is removed, the
machine will continue to run at high RPM for 12 seconds, then drop to
low RPM, unless a load is re-applied during that 12 second delay
CHARGING
SYSTEM LIGHT
(CODE 10926 ONLY)
ENGINE
GLOW
ENGINE
SENSORS
PLUGS
ALTERNATOR
ENGINE
STARTER
IDLE
SOLENOID
PULL HOLD
COIL COIL
PULL COIL
PC BOARD
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
WELD
WINDING
ROTOR
STATOR
ER 120/240 VAC 42 VAC
EXCIT
WINDING
WINDING AUX.WINDING
CURRENT
SENSOR
14
240
PIN
VAC
120
AMPHENALS
6
vac
RECEPTACLES
FLASHING PIN
IDLE SOLENOID OPER TION:
The engine speed is controlled by a two stage solenoid connected to
the engine speed control lever. When the solenoid is inactive, the
engine operates at high RPM, and is controlled by the governor. When
the solenoid is activated, the speed control lever is pulled to a preset
low RPM setting.
The solenoid is powered by battery voltage directly from the run/stop
switch. The control PC board and pull coil PC board activate the pull
and hold coils by providing a path to ground.
When the machine goes to low idle speed, the control PC board
grounds the hold coil of the idle solenoid and at the same time it
sends a signal of about +14VDC to the pull coil PC board. This DC
signal remains at +14VDC for the entire time that the hold coil is
active. When the signal is applied to the Pull coil PC board, the board
will energize the pull coil of the idle solenoid for a brief moment,
normally less than one second. This momentary activation of the pull
coil supplies the needed power to reliably move the speed control
lever to the low idle position.
E 3

THEORY OF OPERATION

SHUNT
IGBTs
POWER
CHOKE
MODULE
AMP
DISPLAY
WELD CONTROL
VOLT
P.C. BOARD
DISPLAY
IDLE
SWITCH
OUTPUT
MODE
WELDING
CONTROL
SWITCH TERMINAL
SWITCH
ARC
CONTROL
+
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