5-3
DESCRIPTION
Of
GENERATOR OPERATION
PERMANENT MAGNET
FOR
INITIAL EXCITATION
STATOR MAIN COIL
.
RECEPTACLE
SURGE
ABSORBER
'""""_I
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
!z
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
:s
increases, the magnetic
flux
at the
rotor's
magnetic pole increases further. Thus the
voltages at the main coil and condmser 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
(8
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
gene.rator 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
:g
flows through the
main
coil to the appliance, a magnetic
flux
is
produced and
serves to increase current
;zn
in
the condenser coil. When current
83
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.
-
25
-
To Next Page
Loading...
Need help?
General
