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E-4

E-4

THEORY OF OPERATION

FIGURE E.4 – CURRENT RANGE SELECTOR, FINE CURRENT ADJUSTMENT AND ENGINE IDLER CIRCUIT

 

ON LATER MODELS

 

 

 

 

 

 

 

 

 

PROTECTION AND IDLER CIRCUITS

 

 

 

 

 

 

 

 

 

ARE ON ONE PC BOARD

 

 

 

 

 

 

 

 

 

PROTECTION

 

 

 

SELECTOR

 

 

 

 

 

RELAY

 

 

 

 

 

 

 

 

 

 

 

 

SWITCH

 

 

 

 

 

 

 

 

 

 

 

 

REED

 

 

 

 

IDLER

 

 

 

 

 

RELAY

NEGATIVE

 

 

BOARD

 

 

 

 

 

CR2

 

 

 

 

 

 

 

 

 

 

OUTPUT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TERMINAL

 

 

 

 

 

 

 

 

115 & 230VAC

 

 

 

 

 

 

 

 

 

 

RECEPTACLES

 

 

 

 

IDLER

 

 

 

 

 

 

 

 

 

SOLENOID

 

 

 

 

 

 

 

 

OIL

OIL

 

 

GENERATOR

 

 

 

 

 

TEMPERATURE

PRESSURE

 

 

 

FRAME

 

 

 

 

 

SENSOR

SENSOR

 

 

 

 

 

CURRENT

 

 

FUEL

 

 

SERIES

 

 

 

 

 

 

SOLENOID

 

 

COILS

 

 

 

 

TRANSFORMER

 

 

RELAY

 

 

 

 

 

 

ALTERNATOR

STATOR

 

 

CR1

 

 

 

 

BRUSHES & COMMUTATOR

 

 

SWITCH

 

 

ARMATURE

 

 

SLIP

 

ENGINE

 

 

 

 

 

 

(NOT PRESENT

ENGINE

MECHANICAL

GENERATOR

 

ARMATURE

ROTOR

 

 

 

ON LATER MODELS)

 

 

 

 

 

 

 

 

 

IGNITION

 

 

COUPLING

 

 

 

SHAFT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ALTERNATOR

 

 

 

 

 

 

 

RINGS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INTERPOLE

 

 

 

 

 

 

 

 

 

COILS

RESIDUAL

 

 

 

 

 

 

STARTER

 

 

MAGNETISM

FLASHING

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MOTOR

 

 

FIELD

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SHUNT

 

 

 

 

 

 

 

 

 

WINDINGS

 

 

 

 

 

 

 

 

 

 

 

 

FIELD

 

 

 

BATTERY

 

 

 

 

 

RECTIFIER

 

 

 

 

 

 

 

GENERATOR

 

 

 

 

 

 

 

 

 

FIELD CONTROL

 

 

POSITIVE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OUTPUT

 

 

 

 

 

 

 

 

 

 

TERMINAL

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ENGINE, GENERATOR ARMATURE AND FRAME, ALTERNATOR STA- TOR AND ROTOR (CONTINUED)

CURRENT RANGE SELECTOR

The selector switch acts as a coarse current adjust- ment by allowing for varying amounts of series wind- ings to be included in the welding current path. The series coils and selector switch are connected in series with the negative output terminal.

FINE CURRENT ADJUSTMENT

The field rheostat control functions as a fine output cur- rent adjustment by controlling the current through the shunt windings. This controls the amount of magnet- ism created in the shunt field windings. Open circuit weld voltage can also be controlled by the field rheo- stat control.

ENGINE IDLER CIRCUIT

The idler solenoid is mechanically connected to the engine governor linkage. When welding current is being drawn, the reed switch CR2 is closed. This sig- nals the idler PC board to release (deactivate) the idler solenoid, which then lets the machine go to a high speed condition. Also, when auxiliary power is being used, the current is passed through the current trans- former. This signals the idler PC board to release the idler solenoid.

When welding ceases or the auxiliary load is removed, a preset time delay of about 15 seconds starts. After approximately 15 seconds the idler PC board activates the idler solenoid, and the machine will return to a low speed condition.

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

CLASSIC II

Page 48
Image 48
Lincoln Electric SVM125-A service manual Current Range Selector, Fine Current Adjustment, Engine Idler Circuit

SVM125-A specifications

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