FIELD OF THE INVENTION
The present invention relates to a stator slot wedge with corresponding stator
slot for improved ventilation of heat from hydro generators.
BACKGROUND OF THE INVENTION
Windings of hydro generator are copper conductors in the form of coils or bars
and are placed into open stator slots. A wedge is provided on the slots after
placement of the bars/coils, and the open end of the slot is locked by the slot
wedge (Ref. Fig. 1).
The slot wedge is normally made from epoxy glass fiber laminate which is used
in stator slot of hydro-generators to hold the conductors firmly in the slot and to
prevent their sagging in the long run of the machine.
During operation of the hydro generator, the heat generated in stator parts i.e.
core and winding, needs to be dissipated by circulating an appropriate volume of
cold air through ventilating ducts provided in the core. To guide the cold air
through these ventilating ducts grooves are provided in stator slot wedges (Ref.
Fig. 2).

In the prior art, hydro generators, the stator core were designed with
rectangular opening for the slot wedge as shown in (Fig.3) and rectangular slot
wedges are provided with cuts/grooves at regular interval in front of the
ventilating ducts, wherein taper grooves are provided as per rotational direction
of rotor. These grooves guide cold air in the ducts to dissipate the heat
generated in the core and windings (Figs. 4 and 5).
It is known that placement of the slot wedges require skilled workmanship and
the manufacturing of the slot wedge is time consuming due to provision of
complicated grooves and contours at regular intervals.
Any error in manufacturing leads to rejection of the slot wedge and any error in
assembly of the slot wedge causes poor ventilation.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a stator slot wedge with
corresponding stator slot for improved ventilation of heat from hydro generators.
Another object of the invention is to propose a stator slot wedge with
corresponding stator slot for improved ventilation of heat from hydro generators
which is capable to dissipate generated heat irrespective of the rotational
discretion of hydro generator's rotor.

A further object of the invention is to propose a stator slot wedge with
corresponding stator slot for improved ventilation of heat from hydro generators
which reduces the cost of manufacturing of the slot wedge.
A still further object of the invention is to propose a stator slot wedge with
corresponding stator slot for improved ventilation of heat from hydro generators
which allows easy assembly of the core windings on the stator slots.
SUMMARY OF THE INVENTION
Accordingly/there is provided a stator slot wedge with corresponding stator slot
for improved ventilation of heat from hydro generators, the hydro generator
comprising a stator having a stator core provided with a plurality of slots to
accommodate corresponding number of conductive coils and bars made of
copper wire and assigned for upper and bottom portions of the stator, the stator
slots having insulating layers along the periphery and supported by slot wedges
configured with plurality of grooves on both longitudinal edges at predefined
intervals; a plurality of ventilation ducts installed to allow supply of cold air to
dissipate the generated heat via the grooves of the slot wedges which forming a
ventilation system, the improvement is characterized in that the slot wedge is
constructed with continuous tapered along both the longitudinal edges; and the
stator slots are correspondingly modified to increase in supply of cold air thereby
improve dissipation of hot air from the hydro generator.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 shows slot layout of a known stator.
Figure 2 shows a stator core including ventilation of heat generated in a prior art
stator.
Figure 3 shows stator slot and slot wedge of a prior art stator.
Figure 4 shows a prior art stator in which the slot wedge is correlated to stator
core height.
Figure 5 shows a slot wedge according to prior art.
Figure 6 shows an improved construction of slot wedge on a stator core
according to the invention.
DETAIL DESCRIPTION OF THE INVENTION
Figure 1 shows a slot layout on a stator core according to prior art copper
conductors (1) constructed in the form of coils and/or bars to act as the
windings. The windings are placed on the open slots on the stator core. The
open ends of the slots are locked with rectangular shaped slot wedge (2). On
each separator (4) is provided between a top winding (la) and a bottom winding
(lb). The slots after placement of the windings are provided with insulation (3)

all along the rectangular shaped periphery, including a lining (5) at the bottom of
the slot (8).
Figure 2 shows that a plurality of ventilation ducts (7) are provided in the stator
core (6) for supplying of cold air to dissipate the heat generated during operation
of the hydro generator.
Figure 3 shows that the stator core (6) provided with rectangular openings (6a),
and rectangular shaped slot wedge (2) constructed with a plurality of grooves
(2a) at regular intervals to guide cool air to the ventilation ducts (7). Figure 4
shows an assembly of the slot wedge and windings on the slots including the
ventilation ducts.
Figure 5 shows the prior art slot wedge with tapered grooves (2a) on both the
longitudinal edges at specified intervals.
Figure 6 shows a modified slot wedge (20 with correspondingly constructed
stator slots (80 on the stator core (6). According to the invention the slot wedge
(20 is constructed with half-tapered grooves (2'a) all throughout on both the
longitudinal edges. Further, the stator slots (80 are correspondingly constructed
to match the half-tapered grooves (2'a) of the slot wedge (20 such that supply
of cool air is increased to allow to maximize ventilation of hot air from the hydro
generator.

WE CLAIM :
1. A stator slot wedge with corresponding stator slot for improved ventilation
of heat from hydro generators, the hydro generator at least comprising a
stator having a stator core provided with a plurality of slots to
accommodate corresponding number of conductive coils and bars made of
copper wire and assigned for upper and bottom portions of the stator, the
stator slots having insulating layers along the periphery and supported by
slot wedges configured with plurality of grooves on both longitudinal
edges at predefined intervals; a plurality of ventilation ducts installed to
allow supply of cool air to dissipate the generated heat via the grooves of
the slot wedges which forming a ventilation system, the improvement is
characterized in that:
- the slot wedge is constructed with a continuous half-tapered grooves
along both the longitudinal edges; and
- the stator slots are correspondingly modified to increase in supply of cool
air thereby improve dissipation of hot air from the hydro generator.

ABSTRACT

A stator slot wedge with corresponding stator slot for improved ventilation of
heat from hydro generators, the hydro generator at least comprising a stator
having a stator core provided with a plurality of slots to accommodate
corresponding number of conductive coils and bars made of copper wire and
assigned for upper and bottom portions of the stator, the stator slots having
insulating layers along the periphery and supported by slot wedges configured
with plurality of grooves on both longitudinal edges at predefined intervals; a
plurality of ventilation ducts installed to allow supply of cool air to dissipate the
generated heat via the grooves of the slot wedges which forming a ventilation
system, the improvement is characterized in that the slot wedge is constructed
with continuous tapered along both the longitudinal edges; and
the stator slots are correspondingly modified to increase in supply of cool air
thereby improve dissipation of hot air from the hydro generator.