Constructionof Alternator

Definition of alternator

An alternator is defined as an alternator that uses a rotating field and a fixed armature to convert mechanical energy into electrical energy.

Components of an alternator

The alternator consists of two main parts: the rotor (rotating) and the stator (stationary).

The construction of alternator

The structure includes an exciting pole on the rotor and an armature conductor on the stator, which senses a three-phase voltage.

Type of rotor

Convex pole type (for low speed)

The word "prominent" means prominent or prominent. Salient pole rotors are usually used in low-speed machines with large diameters and relatively small axial lengths. In this case, the magnetic poles are made of thick laminated steel sections that are riveted together and attached to the rotor with the help of a joint.

The salient features of the polar field structure are as follows

• They have a large horizontal diameter compared to their shorter axial length.

• The pole shoe covers only about 2/3 of the pole distance of the rd.

• The poles are laminated to reduce eddy losses.

• Salient pole motors are typically used for low-speed operation at around 100 to 400 rpm, and they are used in power stations equipped with water turbines or diesel engines.

Cylindrical rotor type (for high speed)

Cylindrical rotors are used for high-speed operation in steam turbine-driven alternators such as turbine generators. These machines are available in a variety of ratings, from 10 MVA to over 1500 MVA. The cylindrical rotor has an even length and shape, allowing for consistent flux cutting in all directions. The rotor is a smooth steel cylinder with grooves on the outer edge for the excitation coil.

Cylindrical rotor alternators are usually designed as 2-pole types with very high speeds

Or 4 pole type, operating speed is

Where f is the frequency of 50 Hz.

Convex pole rotor and cylindrical rotor

The convex pole rotor has a large diameter and short length for low speed operation, while the cylindrical rotor is smooth and balanced for high speed operation.