06-10-2012, 05:24 PM
MANUFACTURING PROCESS OF TURBO GENERATORS
MANUFACTURING.pdf (Size: 1.72 MB / Downloads: 94)
STATOR FRAME:
The stator frame is of welded steel single piece construction. It supports the laminated core and
winding. It has radial and axial ribs having adequate strength and rigidity to minimize core
vibrations and suitably designed to ensure efficient cooling. Guide bars are welded or bolted
inside the stator frame over which the core is assembled. Footings are provided to support the
stator foundation.
STATOR CORE:-
The stator core is stacked from the insulated electrical sheet steel lamination and
mounted in supporting rings over the insulated dovetail guide bars. In order to minimize eddy
current losses core is made of thin laminations. Each lamination layer is made of individual
sections. The ventilation ducts are imposed so as to distribute the gas accurately over the core
and in particularly to give adequate support to the teeth.
The main features of core are –
1. To provide mechanical support.
2. To carry efficiently electric, magnetic flux.
3. To ensure the perfect link between the core and rotor.
THE DIFFERENT OPERATIONS IN MANUFACTURE OF
LAMINATIOS:
Deburring operation:
In this operation the burrs in the sheet due to punching are deburred. There are chances of
short circuit within the laminations if the burrs are not removed. The permissible is about 5
micrometer. For deburring punched sheets are passed under rollers to remove the sharp burs of
edges.
Varnishing:
Then depending on the temperature withstand ability of the machine the laminations are
coated by varnish which acts as insulation. The lamination sheets are passed through conveyor,
which has an arrangement to sprinkle the varnish is obtained. The sheets are dried by a series of
heaters at a temperature of around 260-350 C. Two coatings of varnish are provided in the above
manner till 12-18mm thickness of coat is obtained.
STATOR END COVERS:
The stator end covers are attached to end flanges of stator frame and also rest on the foundation
plate. The end covers are made up of non-magnetic material (Aluminium castings) to reduce
stray load and eddy current losses.
PHASE CONNECTORS:
The phase connectors consist of flat copper sections, which results in low specific current
loading. The phase connectors are wrapped with resin rich mica tape. After curing the
connectors are attached to the pressure plate with clamps and bolts.
RESISTANCE TEMPERATURE DETECTORS :
The temperature measurements on the generator are made with RTDs. They are placed at various
sections of the core and winding. When making measurements with RTDs the resistance element
is exposed to the temperature to be measured.