Robin America RGX180 Service Manual page 23

5-3-2 PRIMARY EXCITING ACTION
The RGX Series employs an exciting coil in the engine mag-
neto for raising the primary voltage. This action is explain-
ed. The RG Series generates a voltag2 when the generator IS
started again because of the residual magnetism remaintng
FC
in the yokes and poles. If a generator of this type is disas-
r-----1
sembled and stored for a long period of time. the residual
I
I
magnetism. may dissipate so that the generator may not
generate a voltage when it is restarted. The RGX Series
rc& ; 1 $EC;
has an exciting coil for primary exciting action to eliminate I
I
L-----J
such a phenomenon.
The primary exciting action of the new type is explained
below.
ENGINE MAGNETO
Fig. 5- 17(A)
When the generator is started. th2 permanent magnet on the
2ngine rotates to generat a voltage in th2 ssciting coil. This
voltage is regulated by a diode in the .AVR to f22d a current
to the generator field coil (FC). (See Fig. 5-l
7(A).)
The rotor is turnsd into an electromagnet by that sun-ent
and rotates so that voltages are generated in ths stator coils
(main coil, sub coil: and DC coil). The voltage generated in
the sub coils is operated by th2 .AVR to f22d a current to in-
crease the field co11 current (See Fig. 5-17(B).) As a result.
the rotor magnetism increases. This operation is repeated to
generate the rated voltage at 50~~ or 6OHz in the main coil
and
DC
coil.
5-3-3 VOLTAGE REGULATING MECHANISM
Connect a load to the AC output terminal and increase cur-
rent. Output voltage varies as shown in Fig. 5-17(C) depend-
ing on whether an automatic voltage regulator is
used
or
not. The operation of the AVR is explained below.
When an AC output is taken, the engine is loaded and its
rpm falls. Also the AC voltage falls due to the voltage arop
caused
by the internal resistance of the coils.
The
XVR
detects this voltage drop and its built-in SCR automatically
increases the current flows to the field coil. As a result, the
rotor magnetism increases. th2 voltag2 lowered b>- th2 .oad
current is raised. and the output voltage is kept constant. If
the AC output is reduced. the SCR operates in the opposite
way to similarly keep the output voltags constant.
MC
4
E
FC 3
AVR
SC
Fig. 5- 17(B)
WITHOUT AVR
RATED VOLTAGE
VilTH AVR
-A
Fig. 5- 17(C)
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