B. The field coil (source page 36 of study unit 3, Appliance repair)
The Armature(or rotor) is a electromagnet inside a motor and alters the magnetic field inside the motor when it rotates. In DC motors it is connected to a Commutator. In AC induction motors the armature isn't connected to a power source.
A motor will turn when only the armature is excited, if there is enough residual magnetism in the field.
Because the armature (or rotor) has no external connection. The currents that produce torque from the rotor are induced by the magnetic field in the machine, so there is no commutator, no brushes and no armature reaction.
if there are magnets on the stator and the commutator is phased properly this is known as a permanent magnet dc motor the starting torque is dependent on armature current and the strength of the magnet the speed is directly proportional to the armature voltage a shunt motor needs the field energized for starting. more field more starting torque
A shunt generator is a machine with a rotating set of coils of wire embedded in the iron core in its armature (the spinning part), and a 'commutator' and brushes that carry the current from the (spinning) windings on the armature to the stationary external electrical load. It also has a 'field' winding that creates a stationary magnetic field inside the machine, that the armature coils are spun in. As the windings spin, they cut the stationary field and generate an alternating voltage. As well as providing a moving connection to the coils, the commutator and brushes act like a switch, reversing the connections from the coils to the external circuit each time the waveform changes polarity from positive to negative and vice versa. This creates direct current in the external circuit and load. In a shunt generator, the field windings are connected in parallel with the armature ('shunt' is a common term for 'in parallel') and the field gets its power ('excitation') from the armature - the machine is 'self-excited'. A self-excited generator needs a small 'residual field' in the field's iron core so it can generate a small output from the armature when starting, which is fed to the field, boosting the armature output, which is fed to the field.... and so on, until the field iron core saturates with flux, and the field stops strengthening. Shunt generators are the 'workhorse of the small generator market - they are cheap and simple, have an output voltage that 'droops' a little with increasing load, and most shunt generators can safely be short-circuited - this takes the electrical energy away from the field, and the armature can usually develop only a small output current - not enough to damage it.
yoke,magnetic poles,armature,field winding,shaft,armature winding,commutator
1) When the armature is open. 2) When the Field is open. 3) Commutator segments are internally short.
Armature Commutator Brushes Axle Field Magnet DC power supply
Armature Commutator Brushes Axle Field Magnet DC power supply
Armature Commutator Brushes Axle Field Magnet DC power supply
The Armature(or rotor) is a electromagnet inside a motor and alters the magnetic field inside the motor when it rotates. In DC motors it is connected to a Commutator. In AC induction motors the armature isn't connected to a power source.
there are many parts of a dc generator armature, field coil, yoke, body, rotor and commutator.
A motor will turn when only the armature is excited, if there is enough residual magnetism in the field.
I had a 28 volt motor armature and field rewired,it now turns the wrong way,the technician says it has the wrong commutator installed,,and cannot find a new one.
If there is a commutator, it means you are dealing with a DC motor.The commutator acts like a switch to supply voltage to a revolving armature from the stationary brush assembly.A commutator has commutator bars, each seperated by mica insulation. Each coil of the rotating armature is connected to two bars that are in directly opposite positions across each diameter of the armature.The total number of commutator bars depends on the design of the windings on the armature: either "lap" or "wave" windings can be used on a DC motor or generator which is provided with a commutator.For more information see the answer to the Related question and also the Related link shown below.
Because the armature (or rotor) has no external connection. The currents that produce torque from the rotor are induced by the magnetic field in the machine, so there is no commutator, no brushes and no armature reaction.
if there are magnets on the stator and the commutator is phased properly this is known as a permanent magnet dc motor the starting torque is dependent on armature current and the strength of the magnet the speed is directly proportional to the armature voltage a shunt motor needs the field energized for starting. more field more starting torque