Question

Describe the principle, construction and working of a single-phase A.C Generator.

Answer 1

Hint : Remember the principle of EMI, and the basic working of the A.C Generator. It will be easier to graph the cycles if required. Also understand the importance of every component in the A.C Generator.

Complete Step By Step Answer:
Introduction: The A.C generator is a device used for converting mechanical energy into electrical energy i.e., it generates electricity through mechanical work.
Principle: It works on the principle of Electromagnetic induction. According to that, a current is produced because of voltage production (electromotive force) due to a changing magnetic field. This process is called Electromagnetic Induction.

Construction: Essential Parts:
Armature: An armature is a large number of loops/turns of insulated copper wire wound over a laminated soft iron core.
Field magnets: These are magnets that can alter from permanent magnets or electromagnets according to power.
Slip rings: Slip rings are the metal rings ${R_1}$ and ${R_2}$ connected to the ends of the armature and they rotate along with it.
Brushes: ${B_1}$ and ${B_2}$ are two flexible carbon brushes used to provide contact with the slip rings and pass the current from armature to external power.
Working: Armature $\left( {ABCD} \right)$ rotates mechanically in an anticlockwise direction in the magnetic field. Due to this, the flux changes and E.M.F is induced in the coil. The direction of induced E.M.F is given by Fleming’s right hand rule. The working cycle can be divided into two halves.
In the First half cycle, $AB$ moves downwards and $CD$ moves upwards. The current flows in the armature along $DCBA$ , and the current flows from ${B_1}$ to ${B_2}$ in the external circuit.
In the Second half cycle, $AB$ moves upwards and $CD$ moves downwards. The current flows in the armature along $ABCD$ , and the current flows from ${B_2}$ to ${B_1}$ in the external circuit.

Note :
A.C Generators are widely used in electric power plants. It supplies electrical energy in the form of an A.C Current. The supply to the machine is bi-directional, since an A.C Current is induced as output in the circuit.