Theory Of Operation; General Description; Battery, Starter, Engine Alternator, And Protection Circuits - Lincoln Electric SHIELD-ARC SVM128-A Service Manual

E-2
FIGURE E.2 – BATTERY, STARTER, ENGINE ALTERNATOR, AND PROTECTION CIRCUITS
PROTECTION
TEMPERATURE
GAUGE
FUEL
INJECTION
PUMP
IGNITION
ENGINE
SWITCH
ALTERNATOR

GENERAL DESCRIPTION

The SA-250 is a heavy duty, engine driven DC arc
welding power source capable of providing constant
current output for stick welding or DC TIG welding.
Also, a total of 3000 watts of auxiliary power is available
at the 115 or 230VAC receptacles.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.

THEORY OF OPERATION

RELAY
IDLER
BOARD
IDLER
SOLENOID
OIL
PRESSURE
SWITCH
SERIES
COILS
GENERATOR
ENGINE
MECHANICAL
COUPLING
ARMATURE
STARTER
MOTOR
BATTERY
SELECTOR
SWITCH
115 & 230VAC
RECEPTACLES
GENERATOR
FRAME
ALTERNATOR STATOR
ARMATURE ROTOR
SHAFT
INTERPOLE
RESIDUAL
COILS
MAGNETISM FLASHING
FIELD
SHUNT
WINDINGS
FIELD
RECTIFIER
GENERATOR
FIELD CONTROL
BATTERY, STARTER, ENGINE
ALTERNATOR, AND PROTECTION
CIRCUITS
The 12VDC battery powers the starter motor and,
through the ignition switch, the engine protection cir-
cuitry. In the event of a low oil pressure or a high
coolant temperature condition, the engine protection
system shuts the engine off. The protection relay mon-
itors the oil pressure switch and the coolant tempera-
ture sensor. If either sensor "faults," the protection relay
deactivates the fuel injection pump, and the engine
shuts down. The engine alternator supplies "charging"
current for the battery circuit.
SA-250
REED
RELAY
NEGATIVE
CR2
OUTPUT
TERMINAL
CURRENT
TRANSFORMER
SLIP
RINGS
POSITIVE
OUTPUT
TERMINAL
E-2