FIELD OF THE INVENTION
The present invention relates to a composite support block used to support field
windings in hydro generators.
BACKGROUND OF THE INVENTION
Hydro generators have a plurality of salient poles in which the field winding is
wrapped around the body of the poles. Due to the generation of large centrifugal
forces during the operation of the machine the windings, which are made of a
relatively flexible material, get deformed and consequently fail. In order to
prevent such unwanted deformation, support blocks are placed in the gaps
between the poles to keep the windings pressed firmly in place. The
arrangement is shown in figure 1.
The known support blocks are made of aluminium/steel. Aluminium is preferred
as it is lighter than steel. A support block is generally held in place with one or
two bolts. Extensive damage to a machine might occur if the bolts fail due to the
large centrifugal forces acting on them while the machine is under operation.
Despite being lighter than steel, the aluminium is still a considerably heavy
material for such a component.
The prior-art support blocks entail the following major disadvantages:
1. Aluminium/steel support blocks currently used are dangerous as they are
heavy and thus have greater centrifugal forces acting on them.
2. Due to their weight, such blocks are hard to assemble on-site.
3. The known support blocks are machined from aluiminium/steel bars. The
manufacturing process is expensive and time consuming.

In view of the above disadvantages, alternate materials needs to be explored to
produce an improved support block that is lighter, has comparable strength and
is less expensive than the aluminium/steel blocks currently used.
OBJECTIVES OF THE INVENTION
The objective is to design a composite support block that, while being
adequately strong for the purpose, is lighter than the metal blocks used to
support field windings in hydro generators. The proposed blocks should
preferably be cheaper to manufacture with a shorter manufacturing cycle time.
SUMMARY OF THE INVENTION
The invention is a composite support block used to support field windings in
hydro generators. It is a V-shaped block made by pressure-molding epoxy glass,
embedding stainless steel plates at highly stressed locations on the block during
the molding of the bock, and coating the assembly with air-drying varnish,
wherein the mold is post-cured at 130°C to 140°C for a period of about 8 to 10
hours.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - Support block made as per prior art
Figure 2 - Support block made as per invention

DETAIL DESCRIPTION OF THE INVENTION
In the existing design (Figure 1), the support block is manufactured by
machining an aluminium/steel forging/bar. In the proposed design (Figure 2),
the support block (1) is composite and manufactured by molding epoxy glass
into the required shape. The structure is reinforced by embedding steel plates
(5) in the areas of high stress concentration. The plates (4) are embedded using
anchor strips (3). Both blocks are similar in size but the weight of the aluminium
block is significantly higher than that of the composite block.
ADVANTAGES OF THE PROPOSED DESIGN
1. Composite blocks are significantly lighter than equivalent aiuminium/steel
blocks of comparable strength. Hence, they are safer.
2. They are easier to assemble on-site.
3. They are cost-effective and have a short manufacturing cycle time.

WE CLAIM:
1. A method of manufacturing a composite support block to rigidly support
field windings in hydro generators comprising:
- forming a V-shaped block by pressure molding epoxy glass and
embedding stainless steel plates at highly stressed locations on the block
during the molding of the block ,
- coating the assembly with air drying varnish, wherein the mold is post-
cured at 130°C to 140°C for a period of about 8 to 10 hours

ABSTRACT

The invention is a composite support block used to support fieid windings in
hydro generators. It is a V-shaped block made by pressure-molding epoxy glass,
embedding stainless steel plates at highly stressed locations on the block during
the molding of the bock, and coating the assembly with air-drying varnish,
wherein the mold is post-cured at 130°C to 140°C for a period of about 8 to 10
hours.