explain the principle and working of electric generator by drawing a labelled diagram
Answers
Answer:
An AC generator converts mechanical energy into electric energy.
Principal : Whenever in a closed circuit (i.e., a coil), the magnetic field lines changes, an induced current is produced.
Construction : It consists of the following four parts.
1. Armature : Armature (abcd), also called the coil, consists of a large number of turns of insulated copper wire would over a soft iron core. It revolves around an axle between the two poles of a strong magnet.
2. Field Magnet : The magnetic field (B) is supplied by a permanent magnet in a small dynamo (also called a magneto) and by an electromagnet in case of a big commercial dynamo (usually called a generator). The poles of the magnet are shown as N-S in figure.
3. Slip Rings : R1 and R2 are two hollow metal rings held at different heights. The end d of the armature coil is connected to ring R1. The end c of the coil is passed through R1 without touching it and is connected to R2. These rings rotate with the rotation of the armature.
4. Brushes or Sliding Contact: B1 and B2 are flexible metal plates or carbon rods. These are called brushes or sliding contacts. B1 is in constant touch with and R1 and B2 is in constant touch with R2. It is with the help of these brushes that the induced current is passed on from the armature and the rings to the external circuit containing a resistance, R and a galvanometer, G. Brushes are stationary i.e. these do not rotate with the rotation of the armature.
Working:-
Eletric generators are based on the principle of electromagnetic induction and converts mechanical energy into electrical energy. An electric generator consists of a rotating rectangular coil placed between the two poles of a permanent magnet.
Electric generators are based on the principle of electromagnetic induction and converts mechanical energy into electrical energy.
An electric generator consists of a rotating rectangular coil placed between the two poles of a permanent magnet.
The two rings R1 and R2 are internally attached to an axle. The axle may be mechanically rotated from outside to rotate the coil inside the magnetic field.
Outer ends of the two brushes B1 and B2 are connected to the galvanometer to show the flow of current in the given external circuit.
When the axle is rotated, arm AB moves up (and the arm CD moves down) in the magnetic field produced by the permanent magnet. Let us say that the coil ABCD is rotated clockwise.
By applying Fleming’s right-hand rule, the induced currents are set up in these arms along the directions AB and CD. Thus, an induced current flows in the direction ABCD. If there are more turns in the coil, the current generated in each turn adds up to give a large current through the coil.
After half rotation, CD and AB reverse direction, and thus, CD starts moving up and AB starts moving down. As a result, the directions of the induced currents in both the arms change.
Such a current which changes direction after equal intervals of time is called an alternating current. Thus, this device is called an AC generator.
To get a direct current, a split-ring type commutator must be used. The generator is thus called a DC generator.
The difference between direct and alternating currents is that the direct current always flows in one direction, whereas the alternating current reverses its direction periodically.
Explanation:
