5-3 DESCRIPTION of GENERATOR OPERATION
PERMANENT MAGNET | STATOR | MAIN COIL | |
FOR INITIAL EXCITATION | |||
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Fig. 5-8
5-3-1 GENERATION Of NO-LOADVOLTAGE
When the generator starts running, the permanent magnet
As one or two condensers are connected to the condenser coil, the small voltage at the condenser coil generates a minute current @Iwhich flows through thecondenser coil. At this time, a small flux is produced withwhich the magnetic force atthe rotor’s magnetic pole is intensified.When this magnetic force is intensified, the respective voltages in the main coil and condenser coil rise up.
As the current @ increases, the magnetic fluxat therotor’s magnetic pole increases further. Thus the voltages at the main coil and condenser coil keep rising by repeating this process.
As AC current flows through the condenser coil, the density of magnetic flux in the rotor changes. This change of magnetic flux induces AC voltage in the field coil, and the diode rectifier in the field coil circuit rectifies this AC voltage into DC.Thus a DC current @ flows through the field coil and magnetizes the rotor core to generate anoutput voltage in the main coil.
When generator speed reaches 2700 to 2800 rpm (50Hztype) or 3000 to 3300 rpm (60Hz type), the current in the condenser coil and field coil increases rapidly.
This acts to stabilize the output voltage of each coils. If generator speed further increases to the rated value, the generator output voltage will reach to the rated value.
5-3-2 VOLTAGEFLUCTUATIONSUNDERLOAD
When the output current @ flows through the main coil to the appliance, a magnetic fluxis produced and serves to increase current @Iin the condenser coil. When current @ increases, the density of magnetic
flux across the rotor core rises. As a result, the current flowing in the fieldcoilincreases andthe
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