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TITLE: ROTOR CENTERING DEVICE FOR HYPROGENERATORS
FIELD OF INVENTION
The invention relates to a novel device for centering of hydrogenerators during
installation at site in association with complete rotating system.
BACKGROUND OF THE INVENTON
Generally hydrogenerators are huge in size, driven by low speed water turbine
and located at far flung remote areas having poor rail/road access imposing
limitations on transportation. Hence hydrogenerators are not being transported
to site in fully assembled condition. Due to such restrictions, the
components/sub-assemblies are supplied loose and assembled at site.
In view of the above, the complete installation and commissioning of the plant is
carried out at site. In the process of installation and commissioning of rotating
machines, rotor centering has been one of critical areas, wherein all the
commissioning engineers are concerned for satisfactory operation of the
hydrogenerators. The generator shaft is coupled with the turbine shaft and
centered with respect to turbine bearing, as shown in Figure - 1. The complete
rotating system is locked nearer to guide bearing, where thrust bearing is located
to support the vertical load of rotating system.

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In prior art and existing practice the process of centering is carried out with the
help of adjusting screws and shaft supporting blocks at four places diametrically
opposite, as shown in figure 2 (A) and (B). The method require additional
machining of guide bearing support ring and additional machined shaft
supporting blocks.
Further, babbitted guide pads are also used to center the rotor and it has been
observed that babbit surface of guide pads get damaged due to higher contact
pressure between shaft and babbit surface.
OBJECT OF THE INVENTION
- Object of the invention is to develop a novel device of centering
hydrogenerator and associated rotating machines as turbine.
- Other object of the invention is to reduce the cost of installation by
elimination of additional machined holes in the guide bearing support and
additional machined shaft supporting blocks.
- Another object of the invention is to restore rigidity of guide bearing
support ring.
- Further the object of the invention is elimination of guide pads for shaft
centering, which used to get damaged quite often.

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- Also the object of the invention is to develop a method which is easily
accessible and approachable to the job consuming less time of installation.
DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT
In figure (1), the rotating system of a hydrogenerator plant has been shown
wherein, generatorshaft (13) is coupled with turbine shaft (14).
In the present invention of rotor centering device three small components i.e
adjusting screw (8), support (9) and reaction arm (10) have been used as shown
in Figure 3(B). The assembled device is fixed in to the holes provided for vapour
seal on to the top plate of bracket (11) with the screw (12) at four places
diametrically opposite as shown in Figure 3(A).
The support (9) is in touch with shaft (13) due to the reaction force applied by
adjusting screw (8) through reaction arm (10).
The radial distanced' as shown in Figure - 1 between turbine shaft (14) and
fixed with foundation (7) at turbine guide bearing (4) is kept uniform throughout
the circumference by adjusting the screw (8) in forward and backward direction.
The centering device of the present invention as shown in Figure 3(B), wherein,
support (9) is in touch with the shaft (13) to push and position the shaft to
maintain the uniform radial distanced' through out the circumference as per
Figure- 1.

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The reaction arm (10) of the device is fixed in existing holes provided for vapour
seal with the help of the screw (12), in top plate of the top bracket (11).
In the process of centering, adjusting screw (8), which plays the crucial role has
the provision of movement in the reaction arm as well as pushes the support for
adjustment of proper centering.
After centering, the new device is locked in position and assembly of bearings
and other components are completed.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:-

FIGURE - 1

shows the schematic layout drawing of the rotating system
of hydrogenerator.

FIGURE - 2(A) shows the existing rotor centering device.
FIGRUE-2(B) shows the detail schematic drawing of rotor centering
device.
FIGURE - 3(A) fixing details of invented rotor centering device.
FIGURE - 3(B) enlarged fixing details of invented rotor centering device

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WE CLAIM
1. A novel device of centering hydrogenerator with respect to turbine
bearing
comprising:-
(a) Adjusting screw (8)
(b) Support element (9)
(c) Reaction Arm (10)
(d) Fixing screw (12)
Which are fixed at four places, diametrically opposite to the rotor shaft,
spaced equally, characterized by radial distance at turbine bearing kept
uniform throughout the circumference.
2. The device as claimed in claim (1), wherein the reaction arm (10) is fixed
in the existing holes provided for vapour seal.
3. The device as claimed in the preceeding claims wherein, the fixing screw
(12) provided for fixing reaction arm (10).
4. The device as claimed in the preceding claims wherein the top plate of the
top bracket (11) provided to hold reaction arm (10) with the help of screw
(12).

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5. The device as claimed in the preceeding claims wherein, the adjusting
screw (8) provided to adjust centering of the shaft through the support
(9).
6. The device as claimed in the preceeding claims wherein, the support (9)
provided to be always in contact with the shaft to apply force to the shaft.
7. A method of centering generator shaft with respect to (13) turbine shaft
(14) by moving the adjusting screw (8) backward and inward, to push the
support (9), applying a force on the shaft for centering.
8. The method as claimed in claim (7), wherein, uniformity of the radial
distanced' at the turbine bearing is maintained throughout the
circumference of the rotor.

OF LS.DAVAR & CO.
APPLICANTS' AGENT
Dated this 11th Day of MARCH 2008

A novel device of centering hydrogenerator with respect to turbine
bearing
comprising:-
(a) Adjusting screw (8)
(b) Support element (9)
(c) Reaction Arm (10)
(d) Fixing screw (12)
Which are fixed at four places, diametrically opposite to the rotor shaft,
spaced equally, characterized by radial distance at turbine bearing kept
uniform throughout the circumference.