Filter
Top Products
5-3
DESCRIPTION
of
GENERATOR OPERATION
PERMANENT
MAGNET
FOR
INITIAL
EXCITATION
STATOR
MAIN
COIL
Fig.
5-8
5-3-1
GENERATION
Of
NO-LOAD VOLTAGE
When the generator starts running, the permanent magnet built-in to the rotor generates
3
to
6V
of
AC
voltage in the main coil and condenser coil wound
on
the stator.
As
one or two condensers are connected to the condenser coil, the small voltage at the condenser
coil generates a minute current
@I
which flows through the condenser coil. At this time, a small flux
is produced with which the magnetic force at the 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 flux at the rotor’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 an output voltage in the main coil.
When generator speed reaches
2700
to
2800
rpm
(50Hz
type) 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
VOLTAGE FLUCTUATIONS UNDER LOAD
When the output current
@
flows through the main
coil
to the appliance, a magnetic flux is produced and
serves to increase current
@I
in the condenser coil. When current
@
increases, the density of magnetic
flux across the rotor core rises.
As
a result, the current flowing in the field coil increases and the
generator output voltage is prevented from decreasing.
-1
-
36
-