DC MACHINE
The action of the commutator is to produce a fixed spatial distribution of
current directions in the armature conductors independent of shaft rotation.
The field created by these currents (armature reaction) is horizontally
directed and is represented by the space vector Ia. The field established by the
excitation of the stator poles is directed along the vertical axis and is
represented by the space vector
expressed as Te = k( Ia x
λ
f
).
λ
f
. The electromagnetic torque may be
DC machine :
DC machine is using the dc power supply for working of motor. There are many types of
electrical DC machine are available namely as:
DC motor
DC generator
DC motor:
Dc motors having two windings. Stator of the motor is having the field winding and rotor of the
motor is having the armature winding. There are three types of the dc motor are as below:
Self excited DC motor:
In this type of Dc motor the field is energies by the supply of the armature winding. No other
separate supply is need for the field excitation.
Separately excited DC motor:
In this type of Dc motor the field is energies by the supply of the armature winding. No other
separate supply is need for the field excitation.Another classification of the motor is also done
according to the field winding connection with armature. There are three types are as below:
Series motor:
In this type of motor the field winding is in series of the armature. So, this type of the motor is
creating motor torque compare to the other motors. Starting torque of this type of motor is very
high. This type of motor is used in the crane and in the elevator. This type of motor is never run
on the no load condition. If it is running on no load condition then very high torque is produced
in the motor and maybe there are chances to blast.
Shunt motor:
In this type of motor the field winding is connected with the parallel of the armature. So, the load
current is divided in the armature current and the field current. The torque of this type of motor is
low as compare to the series motor.
Compound motor:
In this type of motor the field winding is in shunt and as well as in the series of the armature
winding. Now a day these types of motors are used in the industries.
DC generator:
In Dc generator the DC supply is given to the field winding and commutator. The commutator
will do the reversal of the current so it will produce the AC current as same as the ac supply. The
rotor is rotated by using some prime movers. So the rotating field is produce is link with the rotor
and dc output is taken from the rotor by using commutator. In the case of the motor the
commutator is convert dc supply to AC supply and by this means rotor of the DC motor is
produce the rotating field. In the generator the generated ac current is rectified by the
commutator.