SEMINAR ON TURBO GENERATOR


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Main Components of Generator

Stator:
It includes stator frame, stator winding, stator core, generator coolers, stator end covers and temperature measuring devices.
Rotor:
It includes rotor shaft, rotor winding, rotor retaining ring, field connection, fans and bearings.
Bearings:
It includes journal bearings (two in number on the either side of the rotor shaft) and thrust bearing (on to observe the radial thrust of the rotor shaft).
Cooling System:
It includes the cooling circuit required for the effective cooling of the generator.
Excitation System:
The purpose of the excitation system is to provide D.C supply to the field winding. It can be classified into three types. They are:
1. D.C Excitation System
2. Static Excitation System
3. Brushless Excitation System
Insulation system:
Insulation is the property which has enormous resistance to the conductivity that is basically the forbidden gap between valance and conduction bands are very large i.e. formic level very high in insulating materials .The property of good insulating material is non-conductive to electricity and conductor for heat.

STATOR FRAME:

The stator frame is horizontally split type and welded construction and supports the lamination core and the winding. Both the air duct pieces and welded radial ribs provide for rigidly to the stator frame.
 Two things are provided to the stator frame to support the stator on the foundation. The stator firmly fixed to the foundation plates with bolt through the feet.

STATOR CORE:

The stator core is made up of stacked insulation electrical sheet steel lamination with a low loss index and suspended in the stator frame from insulated rectangular guide bars. Axial compression of the stator core is obtained by clamping fingers, pressure plates and non magnetic clamping bolts, which are regulated from the core. The clamping finger ensures a uniform clamping pressure, especially within the range of the teeth and provided for uniform intensive cooling of stator core ends.

STATOR WINDING:

The stator winding is a fractional pitch two layer type, it consisting of individual bars. The bars are located in slots of rectangular cross section which are uniformly distributed on the circumference of the stator core.
 In order to minimize losses, the bars are compared of separately insulated strands which are exposed to 360.degrees transposing.
 To minimize the stator losses in the winding, the strands of the top and bottom bars are separately brazed and insulated from each other.

STATOR END COVER:

End covers of fabricated steel or Aluminum alloy castings are employed with guide vanes on inner side for ensuring uniform distribution of cooling air-gap. In case of 1500 r.p.m generators end windings are first enclosed in glass-epoxy moulded end covers and overall steel outer cover is provided over the stators.