Slide 1: AC GENERATOR 1 weyes57 Slide 2: Presented by
Post Graduate Teacher(Physics),
Government Higher Secondary School,
CHENNAI – 600 068,
TAMIL NADU STATE,
INDIA. 2 weyes57 Slide 3: AC Generator It is a device used for converting mechanical energy into electrical energy.
This was originally designed by a Yugoslav scientist Nikola Tesla 3 weyes57 Slide 4: Principle
It is based on the principle of electromagnetic induction.
An emf is induced in a coil,when it is rotated in an uniform magnetic field. 4 weyes57 Slide 5: Essential Parts of An AC Generator Armature
Carbon Brushes 5 weyes57 Slide 6: Diagram of an AC Generator 6 weyes57 Slide 7: Working of an AC Generator 7 weyes57 Slide 8: Armature It is a rectangular coil consisting of a large number of turns of insulated copper wire wound over a laminated soft iron core. 8 weyes57 Slide 9: Field magnets Permanent magnets are used in low power dynamos. Electromagnet is used in high power dynamos. 9 weyes57 Slide 10: Slip rings The ends of the armature are connected to two hollow metallic rings, which are called slip rings. 10 weyes57 Slide 11: Brushes 1.There are two carbon brushes.
They provide contact with the slip rings.
2.They are used to pass on the current from the armature to the external
Power line through the slip rings. 11 weyes57 Slide 12: Working Whenever there is a change in the orientation of the coil,magnetic flux linked with it changes producing an induced emf in it.
The direction of the induced emf is given by “Fleming’s right hand rule”.
The armature rotates in clock-wise direction in the diagram shown in slide 13. 12 weyes57 Slide 13: When the plane of the coil is parallel or( the coil is at an angle 0) to the field the emf induced is zero.
When the plane of the coil is perpendicular or
( the coil is at an angle π/2) to the field the emf induced is maximum in the positive direction.
When the plane of the coil is at an angle π to the field the emf induced is again becomes zero.
When the plane of the coil is at an angle 3π/2 to the field the emf induced is maximum in the negative direction.
When the plane of the coil is at an angle 2π to the field the emf induced is again becomes zero. 13 weyes57 Slide 14: 14 weyes57 Slide 15: weyes57 15 e = E0 sinωt
E0 = nAB ω
e is the induced emf at any instant of time.
E0 is the peak value of the induced emf.
n is the number of turns of the armature coil.
A is the area of the coil.
B is the intensity of the magnetic field.
ω is the angular frequency of rotation of the coil.
t is the time. Slide 16: 16 weyes57 Fleming’s right hand rule Slide 17: Fleming’s right hand rule 17 weyes57 Slide 18: weyes57 18 Related animations
1.The university of New south Wales.
2.Arizona university Slide 19: weyes57 19 Slide 20: weyes57 20