Why pole pitch is expressed in electrical degrees not in mechanical degrees?

Explanation: Pole pitch is always expressed in electrical degrees, rather than in mechanical degrees. pole pitch = 180 electrical degrees or π electrical radians. Explanation: The EMF is generated in the active lengths only, and these active lengths are called the coil-sides of a coil.

Why is the pole pitch always 180 degrees?

If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. In this situation, two opposite sides of the coil lie under two opposite poles. Hence emf induced in one side of the coil will be in a 180o phase shift with emf induced in the other side of the coil.

What is the difference between electrical degree and mechanical degree?

Mechanical degrees in a motor refers to the rotation of the shaft. 1 revolution of the shaft equals 360 mechanical degrees. Electrical degrees in a motor has to do with the magnetic position of the rotor. One transition from “North” to “South” to “North” again equals 360 electrical degrees.

What is the pole pitch of a DC machine?

The pole pitch is defined as the peripheral distance between centers of two adjacent poles in dc machine. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers.

Why do we use slotted armature in a DC machine?

The purpose of the armature is to rotate the conductors in a uniform magnetic field. The armature is slotted and these slots house the armature conductors. The armature conductors are made of copper and are insulated. The field produced from these conductors is not stationary.

What is the reason behind armature structure for both DC and AC machines being laminated *?

Explanation: The armature windings of both the DC and AC machines have to deal with alternating current only; this is the reason why the armature structure of all rotating machines are laminated in order to reduce the eddy current losses.

What is the difference of DC voltages in the adjoining brushes?

4. What is the difference of DC voltages in the adjoining Brushes? Explanation: Brushes are located electrically in the magnetically neutral region. Due to their location adjoining brushes are at constant DC voltage and the coil in series between the constitute one parallel path.

What is relation between electrical degree and mechanical degree?

Answer: There is relation between electrical and mechanical angle, Electrical angle =P\2 (mechanical angle). The mechanical angle is angle of rotor shaft vs stator, while the electrical angle is the angle between poles (rotor vs stator). If you have one pole pair only, then electric = mechanical.

What is the concept of electrical degree?

Definition of electrical degree 1 : one 360th of a cycle of an alternating current. 2 : one 360th of the angle subtended at the axis of an alternating current by two consecutive field poles of like polarity.

What is the relation between pole pitch and coil pitch?

It is the angular distance between two sides of a coil, measured in terms of armature slots. For example, if there are 36 slots and 4 poles, then the coil pitch is 36/4 = 9 slots. If the coil pitch is equal to the pole pitch, then it is called a full pitch coil.

What is pole pitch in DC power system?

The pole pitch is defined as peripheral distance between center of two adjacent poles in DC machine. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers.

Why is square cross section preferred for the poles of DC machines?

If the cross section of the pole body is square then the length of the mean turn of field winding is minimum. Hence to reduce the copper requirement a square cross section is preferred for the poles of the dc machines. Q: What is the purpose of slot insulation?

Why is the EMF not zero when the field current is reduced?

Q. Why is the emf not zero when the field current is reduced to zero in dc generator? Even after the field current is reduced to zero, the machine is left out with some flux as residue so emf is available due to residual flux. Q. On what occasion dc generator may not have residual flux?

What is the difference between back pitch and front pitch?

A coil advances on the back of the armature. This advancement is measured in terms of armature conductors and is called back pitch. It is equal to the number difference of the conductor connected to a given segment of the commutator. The number of armature conductors or elements spanned by a coil on the front is called front pitch.