Theory of operation, Excitation (flashing), Main shunt, interpole and series coils – Lincoln Electric CLASSIC I SVM134-A User Manual

Page 41: Engine

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ENGINE, MAIN GENERATOR
ARMATURE AND FRAME AND DC
EXCITER

EXCITATION (FLASHING)

The main generator armature and the exciter arma-
ture are mechanically coupled to the engine. When
the engine is started and running, the residual mag-
netism that is stored in the exciter pole pieces is
induced upon the exciter armature. This causes the
exciter to "build-up" and produce a DC output volt-
age. This DC voltage is applied, via the field rheostat
control, to the main generator shunt field coils. The
exciter output is also connected to the 115VDC recep-
tacle.

MAIN SHUNT, INTERPOLE AND SERIES
COILS

The generator armature rotates within the magnetic
field created by the shunt field windings. A DC voltage
is induced in the armature and is transferred, through
the armature commutator and brushes, to the series
and interpole coils. The interpole coils, which are con-
nected in series with the positive output terminal, are
located so as to counteract any magnetic influences
that could cause mechanical distortion in the rotating
armature. The series coils are designed to oppose or
"buck" the DC voltage that is generated in the arma-
ture.

THEORY OF OPERATION

E-3

CLASSIC I

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

FIGURE E.3 – ENGINE, MAIN GENERATOR ARMATURE AND FRAME AND DC EXCITER

NEGATIVE
OUTPUT
TERMINAL

POSITIVE
OUTPUT

TERMINAL

RESIDUAL

MAGNETISM

ARMATURE

SHAFT