Title of Invention	METHOD AND DEVICE FOR IN-SITU REPAIR OF HOLLOW CONDUCTOR ELEMENTS OF A STATOR WINDING OF TURBOGENERATORS
Abstract	The invention in this case is based on the innovative concept of carrying-out the repair work without taking out the stator winding bar and simultaneously ensuring reliable leakage-free quality of the repaired job / brazed joints. This objective is achieved by the invention of an innovative method of metal jacketing around the damaged water carrying conductors. The jacket is placed and brazed between electrical contact sleeve and water box bottom part and thereby making the leak-proof water path upto the water box. Accordingly there is provided a repair method which includes the steps of removal of water box top part; method of cleaning the choked hollow conductors; in-situ brazing of innovatively designed metallic jacket around damaged hollow conductors between electrical contact sleeve and water box bottom part by suitable process; ensuring a space for taking out electrical connection studs; and checking the individual water flow from all hollow conductors of the thus repaired bar. The invention further provides a special device that takes care of uniform heating all-around while holding the water box part to be replaced within the limited space as well as hydraulic/ pneumatic testing of the resulting joints to ensure healthiness of the repaired bar. Exemplary embodiments of the invention and further advantages which can be achieved thereby are explained in more detail in the following text, with reference to the drawing.

Title of Invention

METHOD AND DEVICE FOR IN-SITU REPAIR OF HOLLOW CONDUCTOR ELEMENTS OF A STATOR WINDING OF TURBOGENERATORS

Abstract

The invention in this case is based on the innovative concept of carrying-out the repair work without taking out the stator winding bar and simultaneously ensuring reliable leakage-free quality of the repaired job / brazed joints. This objective is achieved by the invention of an innovative method of metal jacketing around the damaged water carrying conductors. The jacket is placed and brazed between electrical contact sleeve and water box bottom part and thereby making the leak-proof water path upto the water box. Accordingly there is provided a repair method which includes the steps of removal of water box top part; method of cleaning the choked hollow conductors; in-situ brazing of innovatively designed metallic jacket around damaged hollow conductors between electrical contact sleeve and water box bottom part by suitable process; ensuring a space for taking out electrical connection studs; and checking the individual water flow from all hollow conductors of the thus repaired bar. The invention further provides a special device that takes care of uniform heating all-around while holding the water box part to be replaced within the limited space as well as hydraulic/ pneumatic testing of the resulting joints to ensure healthiness of the repaired bar. Exemplary embodiments of the invention and further advantages which can be achieved thereby are explained in more detail in the following text, with reference to the drawing.

Full Text	2 FIELD OF INVENTION The invention relates to a method for in-situ repair of damaged hollow copper conductors and water boxes of water-cooled stator winding of electrical machines. BACKGROUND OF INVENTION The stator winding bar of water-cooled turbogenerators contain typically a combination of Hollow and Solid copper conductors. Cooling water flows inside Hollow copper conductors. All the solid and hollow copper conductors are brazed to contact sleeve which provides electrical connection to the other winding bar. The solid conductors are terminated at the contact sleeve while the hollow copper conductors are brought out and brazed into the water box which is made in two parts. The hollow conductors are brazed to it as well as to one another. 3 Water box top part also contains nipple for water hose connection to the water header. The two parts are brazed together and the water chamber is formed. In the typical design, the hollow copper conductors between contact sleeve and water box are not covered with outer insulation and are exposed to the surrounding gas environment. The gap so created between contact sleeve and water box is required to pass the clamping studs. In the water-cooled stator winding of electrical machines, the coolant is supplied from circular water headers via insulating hoses to these water boxes at end of winding bars. In-situ repair of the contact sleeve and water box / conductors requires development of special process and toolings because of the space limitation and special brazing requirements of different components to one another. The process should take care that the brazing material of already brazed component does not flow out while replacing the damaged part by subsequent in-situ brazing. The insulation of the winding bar under repair and all others nearby is also to be saved from getting damaged due to heat / fire. There is no space available for fixing the conventional brazing tools. Therefore, conventional methods could not be employed so far. 4 Due to the aforesaid limitations, so far no method could be developed for in-situ repair of these water-cooled stator winding bars where hollow copper conductors and / or water box part are damaged. According to the existing practice, whenever a fault occurs in the stator winding bar is area, the winding bar is to be replaced with a new bar. However, replacement of the lower bar requires removal of complete one pitch of upper bar (minimum 16-20 bars). Hence conventional bar replacement method is a very costly process as it requires new winding bars, new fixing materials and much longer shut down. OBJECTS OF THE INVENTION It is therefore an object of the invention to propose a method which can be carried out to repair the bar damages in-situ without removal of the stator winding bars at site, which eliminates the disadvantages of the prior art. Another object of the invention is to propose a special multi-nozzle burner device that can be assembled within the limited space and which takes care of uniform heating all-around while holding the water box part, and which can be adapted for in-situ brazing of water box damaged part ensuring leak proof joint of the replaced water box part. 5 A further object of the invention is to propose a corresponding hydraulic/ pneumatic testing process of the resulting joints to ensure healthiness of the repaired bar. SUMMARY OF THE INVENTION The invention in this case is based on the innovative concept of carrying-out the repair work without taking out the stator winding bar and simultaneously ensuring reliable leakage-free quality of the repaired job / brazed joints. This objective is achieved by the invention of an innovative method of metal jacketing around the damaged water carrying conductors. The jacket is placed and brazed between electrical contact sleeve and water box bottom part and thereby making the leak-proof water path upto the water box. Accordingly there is provided a repair method which includes the steps of removal of water box top part; method of cleaning the choked hollow conductors; in-situ brazing of innovatively designed metallic jacket around 6 damaged hollow conductors between electrical contact sleeve and water box bottom part by suitable process; ensuring a space for taking out electrical connection studs; and checking the individual water flow from all hollow conductors of the thus repaired bar. The invention further provides a special device that takes care of uniform heating all-around while holding the water box part to be replaced within the limited space as well as hydraulic/ pneumatic testing of the resulting joints to ensure healthiness of the repaired bar. Exemplary embodiments of the invention and further advantages which can be achieved thereby are explained in more detail in the following text, with reference to the drawing. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following explicit description when considered in connection with the drawings, wherein : Fig. 1 Shows a general arrangement of Electrical contact sleeve, Copper Conductors and Water box in a turbogenerator. 7 Fig. 2 Shows a general arrangement of Stator winding bar overhang support and Electrical contact sleeve, Water box, Supply hoses and Water header in a turbogenerator. Fig. 3 Shows a general arrangement of Electrical contact sleeve, spacer and Clamping studs in a turbo generator. Fig. 4 Shows the damages to the hollow copper conductors, water box and nipple in a turbogenerator. Fig. 5 Shows a device adaptable to uniformly heat the water box top part while holding it simultaneously within the limited space according to the invention. Fig. 6 Shows the water jacket employed to repair the damage and removal of water box top part, according to the invention. DETAIL DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referring now to the drawings, wherein reference numeral legends designate the corresponding parts throughout the several figures, the objective used is the repair method which can repair the localized faults in the hollow conductors and 8 water boxes of the stator winding bars of an electrical machine, without necessitating replacement of the complete winding bar as is illustrated above in discussion and also schematically in FIGS. 1 to 6. The stator winding bar of water-cooled turbogenerator contain typically a combination of Hollow and Solid copper conductors (2,3). Cooling water flows inside Hollow copper conductors (3) to dissipate heat generated in the winding bar. All solid/ hollow copper conductors (2,3) are brazed to at least one contact sleeve (1) which provides electrical connection of one bar (TB, BB) to the other bar with the help of a copper spacer (10) disposed in between. The solid conductors (2) are terminated at the contact sleeve (1). Beyond this, only hollow copper conductors (3) are brought out and these are terminated at the water box (4,5). The water box is made in two parts (4,5). The two parts (4,5) of the water box are brazed together. All the hollow conductors (3) are brazed into its bottom part (4) as well as to one another (3). This arrangement is explained in Fig. 1. General arrangement of overhang support structure is shown in Fig. 2. There are two bars in each slot of the stator core. The bar towards the air gap is called "Top bar" (TB) and the bar towards the slot bottom is called "Bottom bar" (BB). The overhang part of these bars (TB, BB) is supported on an insulating cone called "support Ring" (11). The contact sleeve (1) and water connection water box (4,5) are disposed after this support cone (11). The water boxes (4,5) are connected to the water header (12) through water supply hoses (13). Thus there is very limited space available between the support ring (11) and the 9 electrical and water connections. Accordingly innovative tools have been designed to carry out the in-situ repair work. Fig. 3 shows the arrangement of clamping studs (7) used to make electrical connection from one bar (TB, BB) to the other. A copper spacer (10) is placed between the contact sleeves (1) of the lower and upper bars (BB, TB) and the two bars are clamped together using at least four number of said steel clamping studs (7). Two clamping studs (7) pass through a limited space (14) available between the contact sleeve (1) and the water box (4,5). A water jacket (9) is fitted in this space for in-situ repair which takes care of the clamping studs assembly (7,8). Fig. 4 shows the typical locations of localized damages (Dl, D2) in water carrying hollow copper conductors (3), water boxes (4,5) and connection nipples (6). Fig. 5 shows the device (10) invented for replacement (RPWB) of water box top part (5) at site. The device (10) comprises a plurality of gas nozzles (15) and is able to be fitted in the limited space and ensures uniform heating all around under pressed condition. Fig. 6 shows the invented water jacket (9) employed to repair the damages in hollow copper conductors (3). The device (10) is provided with LPG supply via a rubber hose (16). A new brazing joint is done at a location (L). Both the top and bottom bars (TB, BB) having insulations (16,17). 10 ADVANTAGES OF THE INVENTION A. TIME SAVING • So far in-situ repair of such faults in stator winding bars was not feasible. • Hence damaged winding bar had to be replaced. In may cases fault occurs in lower bars at more than one locations. • The replacement of lower bars require removal of upper bars also. Thus earlier repair method amounted to partial or complete rewinding depending upon the extent of fault. • Adequate crane facility to handle larger sets at site may not be available in many cases. Hence generator had to be brought to works for repair & rewinding. • The total time required for restoration of the faulty unit was much longer due to time taken in removal of the stator, its transportation to works, repair/rewinding transportation back to site and recommissioning. 11 • The in-situ repair method invented now has solved the problem and the machine is repaired at site in much shorter time without replacement of winding bars. • Thus the invention has resulted in huge Time saving to the generation utility. B. COST SAVING DUE TO EARLY RESTORATION • Thus this invention will result in extra power generation. • For a 500 MW set, a huge Cost saving will thus be achieved due to extra power generation on account of early restoration of the generator. B. COST SAVING DUE TO LESSER REPAIR COST • The new invented In-situ repair is completed in much shorter time and without replacing any winding bar. • This will amount to lesser man hour cost, lesser material cost and lesser technological / induction brazing machine hours cost. • Therefore Repair Cost saving of substantial amount is achievable by this invention. 12 WE CLAIM 1. A method for in-situ repair of hollow conductors and water box stator winding bars of turbogenerators, the stator winding bar comprises a plurality of solid and hollow copper conductors (2,3) being brazed to atleast one contact sleeve (1) with a spacer (10) disposed in between, and the water box having two parts (4,5) brazed together, the hollow conductors (3) being terminated and brazed in the bottom part (4) of the waterbox, the overhang part of the stator bars (TB, BB) clamped by clamping studs (7) are supported on a support ring (11) thereby leaving a limited space between the water/electrical connections and the support ring (11), the method comprising the steps of: - removing the top part of the water box (5); - cleaning the hollow conductors (3) fitted to the bottom part of water box (4); - placing a metallic jacket (9) around the damaged hollow conductors (3), and between the contact sleeve (1) and the water box bottom part (4); - carrying out in-situ brazing of an copper conductors and the water box connection by ensuring space for taking out the clamping studs (7); and 13 - carrying-out routine hydraulic and electrical testing procedures to check healthiness of the repaired components. 2. A multi nozzle burner device (10) for replacement of the water box top part (5) adaptable in a method as claimed in claim 1, the device comprising : - a plurality of gas nozzles (15) disposed in an inverted U-shape configuration around the limited space available between the assembled bars (TB, BB) and covering the hollow copper tubes (3)such that the device in first aspect ensures uniform heating of the brazable components and in a second aspect protects the already brazed components from any damage, and - a LPG source connected via a rubber hose pipe (16) for feeding the multi nozzles (15). 3. A method of removing the damaged water box without taking out the stator winding bar comprising in a method as claimed in claim 1 comprising the steps of: • protecting the brazed joint of healthy water box bottom part; 14 • heating the water box top part; • removing the water box damaged part without damaging the braze joint of the bottom part. 4. A method to clean the water flow ducts of the hollow copper conductors having molten metal inside the conductors in a method as claimed in claim 1, comprising the steps of : • removing metallic debris from the surface of the conductors; • process to remove molten metal from inside the hollow duct of conductors using special drills, wedges and duct callibraters; • clearing the water path of the damaged conductors brazed in the water box; • placing suitable material inside ducts of hollow Cu-conductors that melts after brazing and to ensure that the brazing alloy does not enter inside the damaged conductor ducts and ducts cleared once are not choked again while rebrazing the water box top part and; 15 • checking the water flow from individual conductors to ensure no choking after brazing metal jacket all around and before replacing the top part of the water box. 5. A method as claimed in claim 1, wherein process and selection of brazing material having different melting temperatures is selected so that brazing material from the already brazed water box bottom part and brazing material of conductors does not flow out while brazing the water box top part. 6. A method for in-situ repair of hollow conductors and water box stator winding bars of turbogenerators, as substantially described and illustrated in the accompanyinq drawings. The invention in this case is based on the innovative concept of carrying-out the repair work without taking out the stator winding bar and simultaneously ensuring reliable leakage-free quality of the repaired job / brazed joints. This objective is achieved by the invention of an innovative method of metal jacketing around the damaged water carrying conductors. The jacket is placed and brazed between electrical contact sleeve and water box bottom part and thereby making the leak-proof water path upto the water box. Accordingly there is provided a repair method which includes the steps of removal of water box top part; method of cleaning the choked hollow conductors; in-situ brazing of innovatively designed metallic jacket around 6 damaged hollow conductors between electrical contact sleeve and water box bottom part by suitable process; ensuring a space for taking out electrical connection studs; and checking the individual water flow from all hollow conductors of the thus repaired bar. The invention further provides a special device that takes care of uniform heating all-around while holding the water box part to be replaced within the limited space as well as hydraulic/ pneumatic testing of the resulting joints to ensure healthiness of the repaired bar. Exemplary embodiments of the invention and further advantages which can be achieved thereby are explained in more detail in the following text, with reference to the drawing.

Full Text

2
FIELD OF INVENTION
The invention relates to a method for in-situ repair of damaged hollow copper
conductors and water boxes of water-cooled stator winding of electrical
machines.
BACKGROUND OF INVENTION
The stator winding bar of water-cooled turbogenerators contain typically a
combination of Hollow and Solid copper conductors. Cooling water flows inside
Hollow copper conductors. All the solid and hollow copper conductors are brazed
to contact sleeve which provides electrical connection to the other winding bar.
The solid conductors are terminated at the contact sleeve while the hollow
copper conductors are brought out and brazed into the water box which is made
in two parts. The hollow conductors are brazed to it as well as to one another.

3
Water box top part also contains nipple for water hose connection to the water
header. The two parts are brazed together and the water chamber is formed. In
the typical design, the hollow copper conductors between contact sleeve and
water box are not covered with outer insulation and are exposed to the
surrounding gas environment. The gap so created between contact sleeve and
water box is required to pass the clamping studs.
In the water-cooled stator winding of electrical machines, the coolant is supplied
from circular water headers via insulating hoses to these water boxes at end of
winding bars.
In-situ repair of the contact sleeve and water box / conductors requires
development of special process and toolings because of the space limitation and
special brazing requirements of different components to one another. The
process should take care that the brazing material of already brazed component
does not flow out while replacing the damaged part by subsequent in-situ
brazing. The insulation of the winding bar under repair and all others nearby is
also to be saved from getting damaged due to heat / fire. There is no space
available for fixing the conventional brazing tools. Therefore, conventional
methods could not be employed so far.

4
Due to the aforesaid limitations, so far no method could be developed for in-situ
repair of these water-cooled stator winding bars where hollow copper conductors
and / or water box part are damaged.
According to the existing practice, whenever a fault occurs in the stator winding
bar is area, the winding bar is to be replaced with a new bar. However,
replacement of the lower bar requires removal of complete one pitch of upper
bar (minimum 16-20 bars). Hence conventional bar replacement method is a
very costly process as it requires new winding bars, new fixing materials and
much longer shut down.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a method which can be
carried out to repair the bar damages in-situ without removal of the stator
winding bars at site, which eliminates the disadvantages of the prior art.
Another object of the invention is to propose a special multi-nozzle burner device
that can be assembled within the limited space and which takes care of uniform
heating all-around while holding the water box part, and which can be adapted
for in-situ brazing of water box damaged part ensuring leak proof joint of the
replaced water box part.

5
A further object of the invention is to propose a corresponding hydraulic/
pneumatic testing process of the resulting joints to ensure healthiness of the
repaired bar.
SUMMARY OF THE INVENTION
The invention in this case is based on the innovative concept of carrying-out the
repair work without taking out the stator winding bar and simultaneously
ensuring reliable leakage-free quality of the repaired job / brazed joints.
This objective is achieved by the invention of an innovative method of metal
jacketing around the damaged water carrying conductors. The jacket is placed
and brazed between electrical contact sleeve and water box bottom part and
thereby making the leak-proof water path upto the water box.
Accordingly there is provided a repair method which includes the steps of
removal of water box top part; method of cleaning the choked hollow
conductors; in-situ brazing of innovatively designed metallic jacket around

6
damaged hollow conductors between electrical contact sleeve and water box
bottom part by suitable process; ensuring a space for taking out electrical
connection studs; and checking the individual water flow from all hollow
conductors of the thus repaired bar.
The invention further provides a special device that takes care of uniform heating
all-around while holding the water box part to be replaced within the limited
space as well as hydraulic/ pneumatic testing of the resulting joints to ensure
healthiness of the repaired bar.
Exemplary embodiments of the invention and further advantages which can be
achieved thereby are explained in more detail in the following text, with
reference to the drawing.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
A more complete appreciation of the invention and many of the attendant
advantages thereof will be readily obtained as the same becomes better
understood by reference to the following explicit description when considered in
connection with the drawings, wherein :
Fig. 1 Shows a general arrangement of Electrical contact sleeve, Copper
Conductors and Water box in a turbogenerator.

7
Fig. 2 Shows a general arrangement of Stator winding bar overhang support and
Electrical contact sleeve, Water box, Supply hoses and Water header in a
turbogenerator.
Fig. 3 Shows a general arrangement of Electrical contact sleeve, spacer and
Clamping studs in a turbo generator.
Fig. 4 Shows the damages to the hollow copper conductors, water box and
nipple in a turbogenerator.
Fig. 5 Shows a device adaptable to uniformly heat the water box top part while
holding it simultaneously within the limited space according to the invention.
Fig. 6 Shows the water jacket employed to repair the damage and removal of
water box top part, according to the invention.
DETAIL DESCRIPTION OF PREFERRED EMBODIMENTS OF
THE INVENTION
Referring now to the drawings, wherein reference numeral legends designate the
corresponding parts throughout the several figures, the objective used is the
repair method which can repair the localized faults in the hollow conductors and

8
water boxes of the stator winding bars of an electrical machine, without
necessitating replacement of the complete winding bar as is illustrated above in
discussion and also schematically in FIGS. 1 to 6.
The stator winding bar of water-cooled turbogenerator contain typically a
combination of Hollow and Solid copper conductors (2,3). Cooling water flows
inside Hollow copper conductors (3) to dissipate heat generated in the winding
bar. All solid/ hollow copper conductors (2,3) are brazed to at least one contact
sleeve (1) which provides electrical connection of one bar (TB, BB) to the other
bar with the help of a copper spacer (10) disposed in between. The solid
conductors (2) are terminated at the contact sleeve (1). Beyond this, only hollow
copper conductors (3) are brought out and these are terminated at the water
box (4,5). The water box is made in two parts (4,5). The two parts (4,5) of the
water box are brazed together. All the hollow conductors (3) are brazed into its
bottom part (4) as well as to one another (3). This arrangement is explained in
Fig. 1. General arrangement of overhang support structure is shown in Fig. 2.
There are two bars in each slot of the stator core. The bar towards the air gap is
called "Top bar" (TB) and the bar towards the slot bottom is called "Bottom bar"
(BB). The overhang part of these bars (TB, BB) is supported on an insulating
cone called "support Ring" (11). The contact sleeve (1) and water connection
water box (4,5) are disposed after this support cone (11). The water boxes (4,5)
are connected to the water header (12) through water supply hoses (13). Thus
there is very limited space available between the support ring (11) and the

9
electrical and water connections. Accordingly innovative tools have been
designed to carry out the in-situ repair work. Fig. 3 shows the arrangement of
clamping studs (7) used to make electrical connection from one bar (TB, BB) to
the other. A copper spacer (10) is placed between the contact sleeves (1) of the
lower and upper bars (BB, TB) and the two bars are clamped together using at
least four number of said steel clamping studs (7). Two clamping studs (7) pass
through a limited space (14) available between the contact sleeve (1) and the
water box (4,5). A water jacket (9) is fitted in this space for in-situ repair which
takes care of the clamping studs assembly (7,8). Fig. 4 shows the typical
locations of localized damages (Dl, D2) in water carrying hollow copper
conductors (3), water boxes (4,5) and connection nipples (6). Fig. 5 shows the
device (10) invented for replacement (RPWB) of water box top part (5) at site.
The device (10) comprises a plurality of gas nozzles (15) and is able to be fitted
in the limited space and ensures uniform heating all around under pressed
condition. Fig. 6 shows the invented water jacket (9) employed to repair the
damages in hollow copper conductors (3). The device (10) is provided with LPG
supply via a rubber hose (16). A new brazing joint is done at a location (L). Both
the top and bottom bars (TB, BB) having insulations (16,17).

10
ADVANTAGES OF THE INVENTION
A. TIME SAVING
• So far in-situ repair of such faults in stator winding bars was not
feasible.
• Hence damaged winding bar had to be replaced. In may cases fault
occurs in lower bars at more than one locations.
• The replacement of lower bars require removal of upper bars also.
Thus earlier repair method amounted to partial or complete
rewinding depending upon the extent of fault.
• Adequate crane facility to handle larger sets at site may not be
available in many cases. Hence generator had to be brought to
works for repair & rewinding.
• The total time required for restoration of the faulty unit was much
longer due to time taken in removal of the stator, its transportation
to works, repair/rewinding transportation back to site and
recommissioning.

11
• The in-situ repair method invented now has solved the problem
and the machine is repaired at site in much shorter time without
replacement of winding bars.
• Thus the invention has resulted in huge Time saving to the
generation utility.
B. COST SAVING DUE TO EARLY RESTORATION
• Thus this invention will result in extra power generation.
• For a 500 MW set, a huge Cost saving will thus be achieved due to extra
power generation on account of early restoration of the generator.
B. COST SAVING DUE TO LESSER REPAIR COST
• The new invented In-situ repair is completed in much shorter time and
without replacing any winding bar.
• This will amount to lesser man hour cost, lesser material cost and lesser
technological / induction brazing machine hours cost.
• Therefore Repair Cost saving of substantial amount is achievable by this
invention.

12
WE CLAIM
1. A method for in-situ repair of hollow conductors and water box stator
winding bars of turbogenerators, the stator winding bar comprises a
plurality of solid and hollow copper conductors (2,3) being brazed to
atleast one contact sleeve (1) with a spacer (10) disposed in between,
and the water box having two parts (4,5) brazed together, the hollow
conductors (3) being terminated and brazed in the bottom part (4) of the
waterbox, the overhang part of the stator bars (TB, BB) clamped by
clamping studs (7) are supported on a support ring (11) thereby leaving a
limited space between the water/electrical connections and the support
ring (11), the method comprising the steps of:
- removing the top part of the water box (5);
- cleaning the hollow conductors (3) fitted to the
bottom part of water box (4);
- placing a metallic jacket (9) around the damaged
hollow conductors (3), and between the contact
sleeve (1) and the water box bottom part (4);
- carrying out in-situ brazing of an copper conductors
and the water box connection by ensuring space for
taking out the clamping studs (7); and

13
- carrying-out routine hydraulic and electrical testing
procedures to check healthiness of the repaired
components.
2. A multi nozzle burner device (10) for replacement of the water box top
part (5) adaptable in a method as claimed in claim 1, the device comprising :
- a plurality of gas nozzles (15) disposed in an inverted
U-shape configuration around the limited space
available between the assembled bars (TB, BB) and
covering the hollow copper tubes (3)such that the
device in first aspect ensures uniform heating of the
brazable components and in a second aspect protects
the already brazed components from any damage,
and
- a LPG source connected via a rubber hose pipe (16)
for feeding the multi nozzles (15).
3. A method of removing the damaged water box without taking out the stator
winding bar comprising in a method as claimed in claim 1 comprising the steps
of:
• protecting the brazed joint of healthy water box bottom part;

14
• heating the water box top part;
• removing the water box damaged part without damaging the braze joint
of the bottom part.
4. A method to clean the water flow ducts of the hollow copper conductors
having molten metal inside the conductors in a method as claimed in claim 1,
comprising the steps of :
• removing metallic debris from the surface of the conductors;
• process to remove molten metal from inside the hollow duct of conductors
using special drills, wedges and duct callibraters;
• clearing the water path of the damaged conductors brazed in the water
box;
• placing suitable material inside ducts of hollow Cu-conductors that melts
after brazing and to ensure that the brazing alloy does not enter inside
the damaged conductor ducts and ducts cleared once are not choked
again while rebrazing the water box top part and;
15
• checking the water flow from individual conductors to ensure no choking
after brazing metal jacket all around and before replacing the top part of
the water box.
5. A method as claimed in claim 1, wherein process and selection of brazing
material having different melting temperatures is selected so that brazing
material from the already brazed water box bottom part and brazing
material of conductors does not flow out while brazing the water box top
part.
6. A method for in-situ repair of hollow conductors and water box stator
winding bars of turbogenerators, as substantially described and illustrated
in the accompanyinq drawings.

The invention in this case is based on the innovative concept of carrying-out the
repair work without taking out the stator winding bar and simultaneously
ensuring reliable leakage-free quality of the repaired job / brazed joints.
This objective is achieved by the invention of an innovative method of metal
jacketing around the damaged water carrying conductors. The jacket is placed
and brazed between electrical contact sleeve and water box bottom part and
thereby making the leak-proof water path upto the water box.
Accordingly there is provided a repair method which includes the steps of
removal of water box top part; method of cleaning the choked hollow
conductors; in-situ brazing of innovatively designed metallic jacket around

6
damaged hollow conductors between electrical contact sleeve and water box
bottom part by suitable process; ensuring a space for taking out electrical
connection studs; and checking the individual water flow from all hollow
conductors of the thus repaired bar.
The invention further provides a special device that takes care of uniform heating
all-around while holding the water box part to be replaced within the limited
space as well as hydraulic/ pneumatic testing of the resulting joints to ensure
healthiness of the repaired bar.
Exemplary embodiments of the invention and further advantages which can be
achieved thereby are explained in more detail in the following text, with
reference to the drawing.

Documents:

00819-kol-2007-abstract.pdf

00819-kol-2007-claims.pdf

00819-kol-2007-correspondence others 1.1.pdf

00819-kol-2007-correspondence others.pdf

00819-kol-2007-description complete.pdf

00819-kol-2007-drawings.pdf

00819-kol-2007-form 1.pdf

00819-kol-2007-form 18.pdf

00819-kol-2007-form 2.pdf

00819-kol-2007-form 3.pdf

00819-kol-2007-gpa.pdf

819-KOL-2007-(11-06-2012)-ABSTRACT.pdf

819-KOL-2007-(11-06-2012)-AMANDED CLAIMS.pdf

819-KOL-2007-(11-06-2012)-AMANDED PAGES OF SPECIFICATION.pdf

819-KOL-2007-(11-06-2012)-CORRESPONDENCE.pdf

819-KOL-2007-(11-06-2012)-DRAWINGS.pdf

819-KOL-2007-(11-06-2012)-FORM-13.pdf

819-KOL-2007-(12-04-2012)- CLAIMS.PDF

819-KOL-2007-(12-04-2012)-ABSTRACT.pdf

819-KOL-2007-(12-04-2012)-DESCRIPTION (COMPLETE).pdf

819-KOL-2007-(12-04-2012)-DRAWINGS.pdf

819-KOL-2007-(12-04-2012)-EXAMINATION REPORT REPLY RECIEVED.PDF

819-KOL-2007-(12-04-2012)-FORM 1.pdf

819-KOL-2007-(12-04-2012)-FORM 2.pdf

819-KOL-2007-(12-04-2012)-OTHERS.pdf

819-KOL-2007-(12-04-2012)-PA.pdf

819-KOL-2007-CORRESPONDENCE 1.1.pdf

819-KOL-2007-CORRESPONDENCE.pdf

819-KOL-2007-EXAMINATION REPORT.pdf

819-KOL-2007-FORM 18.pdf

819-KOL-2007-FORM 3.pdf

819-KOL-2007-GPA.pdf

819-KOL-2007-GRANTED-ABSTRACT.pdf

819-KOL-2007-GRANTED-CLAIMS.pdf

819-KOL-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

819-KOL-2007-GRANTED-DRAWINGS.pdf

819-KOL-2007-GRANTED-FORM 1.pdf

819-KOL-2007-GRANTED-FORM 2.pdf

819-KOL-2007-GRANTED-LETTER PATENT.pdf

819-KOL-2007-GRANTED-SPECIFICATION.pdf

819-KOL-2007-OTHERS.pdf

819-KOL-2007-REPLY TO EXAMINATION REPORT.pdf

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Patent Number

253766

Indian Patent Application Number

819/KOL/2007

PG Journal Number

34/2012

Publication Date

24-Aug-2012

Grant Date

22-Aug-2012

Date of Filing

28-May-2007

Name of Patentee

BHARAT HEAVY ELECTRICALS LIMITED

Applicant Address

REGIONAL OPERATIONS DIVISION (ROD), PLOT NO: 9/1, DJBLOCK 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091 BHEL HOUSE, SIRI FORT, NEW DELHI-110049, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	SANJAY KUMAR AGRAWAL	STAFF NO. 1631926, SR. MGR, ELECTRICAL MACHINES ENGINEERING, BHEL, HARIDWAR
2	PRAMOD KUMAR	ST. NO. 1617567, A.F/M, BHEL, HARIDWAR
3	BHAGMAL	ST. NO. 1640283, ARTISAN, BHEL, HARIDWAR
4	DEV RAJ	ST. NO. 1599879, AGM, BHEL, HARIDWAR

PCT International Classification Number

B23K1/00,H02K15/02,3/22

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA