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8-2
GENERATOR OPERATION
INITIAL EXCITATION
PERMANENT MAGNETO
FIELD COIL i
ROTOR
: I
RESIS
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DIODE
8-2-l
1)
GENERATION of NO-LOAD VOLTAGE
2)
3)
41
When the generator starts turning the permanent magneto built-in to the flywheel generates@ 1 to 2\’ of AC voltage
in the main coil and also generates 1 to 4 of AC voltage in the condenser coil.
The capacitor coil is connected to a capacitor so when a voltage is applied to the condenser coil. minimun current
@ flows in the condenser coil. At this time, minimum flus is produced. vvith which the magnetic force of the rotor’s
magnetic pole is intensified. When this magnetic force is intensified. the respective voltages in the main coil and
condenser coil rise. Current 1s flowing in the
condenser coil increases. with the magnetic tlux densit)- of the rotor’s
magnetic pole increasing further. Also. the main coil voltage and condenser coil voltage increases. These voltages
continue rising as this process is repeated.
As current flows in the condenser coil. the magnetic flux density changes. DC voltage is induced in the field coil when
the magnetic flus density varies. Successively. DC current is rectified bl the rectifiers connected to both ends of the
field coil. and DC current @ flows in the field circuit.
With this current. the rotor core is magnetized. allowing the
generator to output steady voltage.
When generator speed reaches 2000 to
2300 rpm (50 Hz specification) or 3000 to 3300 rpm (60 Hz specification). the
current in the condenser coil and field coil increases sudden&. This acts to stabilize the respective coil output voltages.
If generator speed further rises to the rated v-alue. the generator output voltage will reach the rated value.
STATOR
RECEPTACLE
MAIN COIL
CONDENSER
COIL
CONDENSER
L
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A
Fig. 8-2
8-2-2 VOLTAGE FLUCTUATIONS UNDER LOAD
When load current -s flows from the electric equipment to the generator. the magnetic flux which is produced as current
.s flows in the main coil. this serves to increase current ‘$ flowing in the capacitor coil. With current @increased. the
magnetic flux density across the rotor core rises. As a result. the current flowing in the field coil increases, and the genera-
tor output voltage is prevented from decreasing.
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