1. Generators use rotating coils inside magnets or rotating magnets inside coils to induce alternating current through electromagnetic induction. 2. As the coil or magnet rotates in the magnetic field, the changing magnetic flux produces a force on the charges in the coil, driving an alternating current. 3. Large generators have a stationary stator surrounding a rotating rotor to efficiently produce three-phase power for industrial use.

3. Induced Current in a Generator
• The effect of inducing a current in a coil by
moving a magnet inside it
is used for the generation of electricity in power
plants
• There are two types of generator or dynamo.
Both turn rotational energy into electrical energy.
1. One type involves rotating a coil inside a
magnet.
2. The other type involves rotating a magnet
inside a coil
Both types produce ALTERNATING CURRENT.
• gcsescience.com

4. • An electric generator consists of a magnet, which
creates a magnetic field, and a loop of wire
which rotates in the magnetic field. As the wire
rotates in the magnetic field, the changing
strength of the magnetic field through the wire
produces a force which drives the electric
charges around the wire. AS the loop spins, the
direction of the force changes, so too then does
the direction of the current The changing
direction of the force after every 180 degrees of
rotation gives the alternating current.

6. THREE PHASE POWER
• The power plant produces three different phases of AC power
simultaneously, and the three phases are offset 120 degrees from
each other. If you were to look at the three phases on a graph, they
would look like this relative to ground:

7. CONFORMANCE TO STANDARDS
OF GENERATOR
• IEC : 60034.1 to 60034.15
• IS : 4722, 5422, 7132, 7306, 7816
• BS : 4999, 5000
• ANSI : C50.10 , C50.12, C50.13, C50.14
• VDE : 0530 Parts 1,2,3 & 4
• VDI : 2056, 2059
• IEEE : 115

8. • MAIN PARTS
• STATOR
• • ROTOR FORGING
• • ROTOR LAMINATIONS
• • ROTOR WINDING
• • FANS
• ROTOR
• • BASE FRAME/STATOR FRAME
• • STATOR CORE
• • STATOR WINDING
• • ENCLOSURE
• OTHER PARTS
• • BEARINGS
• •AIR COOLER
• •FOUNDATION ITEMS
• •EXCITER

9. • BASE FRAME
• • Carries the stator, bearings and the
exciter
• • Transmits forces occurring in the
machine
• to the foundation.
• • Anchored to the foundation with the
help
• of foundation bolts

11. STATOR CORE BUILDING

13. • ENCLOSURE
• • Split design
• • Bottom part rests on base frame and top
• part sits on bottom part.
• • Designed as required for a particular
• degree of protection
• • Plays a role ventilation circuit
• • Output leads, hot and cold air RTD’s,
• Earthing terminals are on bottom part

15. • STATOR FRAME
• • SPLIT CASE TYPE
• • SUPPORTS CORE AND WINDING
• • MECHANICAL STRENGTH IS IMPARTED BY RADIAL
• RIBS AND AXIAL PIPES
• • SIDE AND BOTTOM MOUNTED COOLERS
• • TOP OR BOTTOM OUTPUT LEADS
• •ROUND AND RECTANGULAR SHAPES
• •FIXED TO THE FOUNDATION WITH THE HELP OF
• FOUNDATION BOLTS AND IS DESIGNED TO
• WITHSTAND SUDDEN SHORT CIRCUIT TORQUE.

16. GENERATOR FRAME-BOTTOM HALF

17. GENERATOR FRAME-UPPER HALF

19. ASSEMBLED CORE

20. GENERATOR UNDER ASSEMBLY

24. PLACING THE TUB WITH STATOR IN IMPREGNATION
TANK

27. ROTOR
• Consists of shaft, laminated core, field
• winding, damper winding, winding
• supports fans and sliprings.
• Shaft has axial grooves thus forming a
• spider shaft.
• 2 Nos. of Radial fans mounted on each
• side of rotor for ventilation of
Generator
• Supported on 2 nos. of journal
bearings
• with one Bearing insulated to eliminate
• passage of shaft currents

29. • Rotor coils are of 4 joints
• type
• 􀁑 Semi closed slots with
• side insertion of rotor
• copper strips
• 􀁑 Max. size of rotor copper
• with dovetail punching
• 􀁑 Avoiding of temp.
• bandage for overhang
• winding, only permanent

30. ROTOR
• Rotor coils are of 4 joints
• type
• 􀁑 Semi closed slots with
• side insertion of rotor
• copper strips
• 􀁑 Max. size of rotor copper
• with dovetail punching
• 􀁑 Avoiding of temp.
• bandage for overhang
• winding, only permanent
• bandage is used

31. ROTOR UNDER MANUFACTURING

32. • ROTOR SHAFT FOR 2 POLE M/CS
• • FORGED FROM A VACUUM CAST STEEL INGOT
• • 2/3RD OF ROTOR BODY CIRCUMFERENCE HAS
• LONGITUDINAL SLOTS TO HOLD THE FIELD
WINDING
• • ROTOR TEETH ARE PROVIDED WITH AXIAL AND
• RADIAL HOLES FOR INTENSIVE COOLING OF END
• WINDING.

38. RETAINING RING
• •NON-MAGNETIC, COLD WORKED MATERIAL
• • WITHSTANDS CENTRIFUGAL FORCES DUE
TO THE
• END WINDINGS
• • SHRUNK FIT HUB REINFORCES RETAINING
RING
• AND SECURES THE END WINDING IN THE
AXIAL
• DIRECTION
• • SNAP RING PROTECTS AGAINST AXIAL
• DISPLACEMENT OF THE RETAINING RING.
• • SHRINK SEAT AREA IS SILVER PLATED

43. Four Flute cooling system for
Rotor

47. BEARINGS
• Cylinderical journal bearings
• • Self aligning type
• • Made in two halves.
• • Mounted on the pedestal which is also
in
• two halves.
• • Duplex type RTD’s to measure
bearing
• temperature.

51. Ventilation Scheme of VPI Generator

54. View of a VPI , 125 MW
Generator

55. ROTOR INSERTION