Why we use distributed winding?

Why we use distributed winding?

Advantages of Distributed Winding: It reduces harmonics present in the generated emf which also improves the sine waveform. It reduces armature reaction and improves cooling. The coil is distributed over the slots, so the core (copper and iron) is fully used. It improves the mechanical strength of the winding.

What is Chorded pitch winding?

A stator winding using fractional pitch coil is called as a chorded winding. If the span of the coil is reduced by an angle of electrical, then the coil span will be (180 − α) electrical degrees. In case of a full-pitch coil, the two coil sides span a distance exactly equal to the pole pitch of 180° electrical.

Why are short Chorded winding employed in induction motor?

Short pitch winding improve the waveform of generated emf i.e. generated emf can be made to approximate to a sine wave more easily and the distorting harmonics can be reduced or totally eliminated. In order to compensate for this reduction in Generated EMF, more number of turns and therefore more copper is required.

Which type of winding is used in synchronous motor?

The damper winding is used in Synchronous Motor to provide starting torque and the damper winding is used in the synchronous alternator to eliminate damping or hunting.

How does distributed winding reduce harmonics?

The technique used for modification in winding distribution includes the optimization of conductors per slots and the slot swapping in each phase. This method effectively reduces the dominant lower order harmonics, however, the number of harmonics reduced depends on the slots per pole per phase in the machine.

Why the distributed winding is always used in armature of AC induction machine?

It reduces harmonic emf and so waveform is improved. It also diminishes the armature reaction. 3. Even distribution of conductors, helps for better cooling.

What is the difference between full pitch and Chorded windings?

A stator winding using fractional pitch coil is called a chorded winding. In case of a full pitch coil, the distance between the two sides of the coil is exactly equal to the pole pitch of 180⁰ electrical. As a result, the voltage in a full pitch coil is such that the voltage of each side of the coil is in phase.

What is meant by short Chorded coil?

This can be seen in the figure below. Short Pitch / Chorded Coil: Thus we can define a Short Pitch Coil as the coil having the coil span (Coil Span is defined as the space angle between the two coil sides of a coil) less than 180 degree. A short pitched coil is also known as Chorded Coil.

Why synchronous motors are not self starting?

Starting methods Above a certain size, synchronous motors are not self-starting motors. This property is due to the inertia of the rotor; it cannot instantly follow the rotation of the magnetic field of the stator.

Why Sector winding is used in synchronous motor?

By providing damper windings in the rotor of synchronous motor “Hunting of machine”can be suppressed. When there is change in load, excitation or change in other conditions of the systems rotor of the synchronous motor will oscillate to and fro about an equilibrium position.

Why damper winding is used in an alternator?

Main Purpose of damper winding in the generator Prevents hunting (momentarily speed fluctuations) in the alternator, Increases the transient stability. Provides high starting torque to the synchronous motor.

Why is a corded winding used in synchronous machines?

Corded winding is used in synchronous machines because of the following factors: A most important factor in using corded winding is to reduce harmonics. As even and triplen harmonics are already absent. Next effective harmonics come is 5th and 7th. Chording factor =cos (na/2) so to eliminate particular harmonics angle should be 90 °.

What is the chording factor of Corded winding?

A most important factor in using corded winding is to reduce harmonics. As even and triplen harmonics are already absent. Next effective harmonics come is 5th and 7th. Chording factor =cos (na/2) so to eliminate particular harmonics angle should be 90 °. Where “n” is nth harmonics and “a” is the chording angle.

What is the working principle of synchronous generator?

In a synchronous generator, a DC current is applied to the rotor winding producing a rotor magnetic field. The rotor is then turned by external means producing a rotating magnetic field, which induces a 3-phase voltage within the stator winding.

What is a chorded coil?

It is also called a chorded coil. The short pitch coil factor is shown in the figure below: A stator winding using fractional pitch coil is called a chorded winding. If the span of the coil is reduced by an angle α electrical degrees, the coil span will be (180 – α) electrical degrees.