A shunt DC motor connects the armature and field windings in parallel or shunt with a common D.C. power source. This type of motor has good speed regulation even as the load varies, but does not have the starting torque of a series DC motor.
Similarly, it is asked, what is the purpose of a shunt?
In electronics, a shunt is a device which allows electric current to pass around another point in the circuit by creating a low resistance path.
A shunt motor has the field windings connected in parallel with the armature and a series motor has the field windings connected in series with the armature. Shunt DC Motor is used in Constant Torque Application and Series DC Motor is used where High starting torque required.
Motor armature current is decided by the load. On less load or no load, the armature current drawn by the motor is very small. and on no load as I is small hence flux produced is also very small. This is the reason why series motor should never be started on light loads or no load conditions.
In d.c shunt motor if field winding supply is removed the motor back emf will drop to zero, hence the armature will draw more current to make up the emf.this results in blowing up of fuse. In dc series motor the motor will go to infinite speed (theoretically) as flux is inversely proportional to the speed
Shunt DC Motors operate on direct current. As such, the field windings and armature are connected in a parallel combination, and in electrical terminology a parallel combination is known as a shunt. This type of motor is a "shunt-wound" DC Motor and the type of winding is called a shunt winding.
The series DC motor is an industry workhorse for both high and low power, fixed and variable speed electric drives. Applications range from cheap toys to automotive applications. They are inexpensive to manufacture and are used in variable speed household appliances such as sewing machines and power tools.
There are 4 main types of DC motors:
- Permanent Magnet DC Motors. The permanent magnet motor uses a permanent magnet to create field flux.
- Series DC Motors. In a series DC motor, the field is wound with a few turns of a large wire carrying the full armature current.
- Shunt DC Motors.
- Compound DC Motors.
The field winding in shunt motor is connected in parallel to the armature winding and the supply. If we assume that the supply voltage is constant then flux also becomes constant. At the rated speed the back emf also becomes nearly constant if the load is same.
Working: When electric voltage is supplied to the shunt DC motor, due to high resistance of the shunt winding, it draws very low current. The armature draws high current, thus also generating a high magnetic field. The motor starts rotating as the magnetic field of the armature and shunt winding interact.
Shunt Wound DC Motor. In case of a shunt wound DC motor or more specifically shunt wound self excited DC motor, the field windings are exposed to the entire terminal voltage as they are connected in parallel to the armature winding as shown in the figure below.
A shunt generator is a type of direct current electric generator in which field winding and armature winding are connected in parallel, and in which the armature supplies both the load current and the field current.
Its high starting torque makes it particularly suitable for a wide range of traction applications. Industrial uses are hoists, cranes, trolly cars, conveyors, elevators, air compressors, vacuum cleaners, sewing machines etc.
When the armature of a d.c. motor rotates under the influence of the driving torque, the armature conductors move through the magnetic field and hence e.m.f. is induced in them as in a generator. The induced e.m.f. acts in opposite direction to the applied voltage V (Lenz's law) and in known as back or counter e.m.f.
A 3 point starter is used for starting a DC shunt motor. A 4 point starter is used for starting a DC compound wound motor.
A DC series motor converts electrical energy to mechanical energy. Its principle of operation is based on a simple electromagnetic law that states that when a magnetic field is created around current carrying conductor and interacts with an external field, rotational motion is generated.
The armature winding is the main current-carrying winding in which the electromotive force or counter-emf of rotation is induced. The current in the armature winding is known as the armature current. The armature windings of dc motors are located on the rotor, since they must operate in union with the commutator.
This is the reason why series motor should never be started on light loads or no load conditions. This can be seen from the speed-armature current and the speed-torque characteristics that on low armature current and low torque condition motor shows a tendency to rotate with dangerously high speed.
The DC compound motor is a combination of the series motor and the shunt motor. It has a series field winding that is connected in series with the armature and a shunt field that is in parallel with the armature.
The universal motor is a type of electric motor that can operate on either AC or DC power. It is a commutated series-wound motor where the stator's field coils are connected in series with the rotor windings through a commutator. It is often referred to as an AC series motor.
To reverse the motor, you need to change the polarity of the supply voltage to either the field winding or the armature winding, but not both. Generally it is better to reverse the field voltage because the field current is less than the armature current, so your reversing switchgear is more lightweight.