Title of Invention	A DEVICE FOR ACCURATE MEASUREMENT OF A ROTOR DIAMETER DURING ERECTION OF HYDROGENERATORS TO REDUCE AN AIR GAP BETWEEN THE ROTATING AND STATIC COMPONENTS
Abstract	A device for accurate measurement of the diameter of a rotor (10) in course of site-erection to reduce an air gap (15) between the rotating and static components (10,12) of a hydrogenerator, the rotor having at least a shaft (10) releasably coupled to a spider (11), a rim (23) built around the spider (11) by lamination of tensile sheet steel, and a plurality of poles (13) disposed in the axial direction of the rim (23), the device comprising a shaft assembly (1) detachably attachable to the spider (11); an arm and bush assembly (2) having a substantially close tolerance in respect of the shaft assembly (1) configured to be slideably insertable in the shaft assembly (1); a counter balance weight (7) provided on the opposite side of the arm and bush assembly (2); at least two rope assemblies (3,4) releasably secured on the arm and bush assembly (2) by means of a special screw (5) having oppositely directional threads (RHT, LHT); and a piano wire (8) interposed in the arm (20) of the arm and bush assembly (2) assembled in a cover plate (6).

Title of Invention

A DEVICE FOR ACCURATE MEASUREMENT OF A ROTOR DIAMETER DURING ERECTION OF HYDROGENERATORS TO REDUCE AN AIR GAP BETWEEN THE ROTATING AND STATIC COMPONENTS

Abstract

A device for accurate measurement of the diameter of a rotor (10) in course of site-erection to reduce an air gap (15) between the rotating and static components (10,12) of a hydrogenerator, the rotor having at least a shaft (10) releasably coupled to a spider (11), a rim (23) built around the spider (11) by lamination of tensile sheet steel, and a plurality of poles (13) disposed in the axial direction of the rim (23), the device comprising a shaft assembly (1) detachably attachable to the spider (11); an arm and bush assembly (2) having a substantially close tolerance in respect of the shaft assembly (1) configured to be slideably insertable in the shaft assembly (1); a counter balance weight (7) provided on the opposite side of the arm and bush assembly (2); at least two rope assemblies (3,4) releasably secured on the arm and bush assembly (2) by means of a special screw (5) having oppositely directional threads (RHT, LHT); and a piano wire (8) interposed in the arm (20) of the arm and bush assembly (2) assembled in a cover plate (6).

Full Text	FIELD OF INVENTION. This invention relates to a device for accurate measurement of the diameter of a rotor in course of site errection to reduce an air gap between the rotating and static components of a hydrogenerator. BACKGROUND OF THE INVENTION. The Hydrogenerators are huge in size due to their slow speed, therefore they are manufactured as sub-assemblies to facilitate the transportation. The sub-assemblies are assembled at site to make a complete generator. The diameter of the rotor of the hydrogenerator is very important since the same rotates in a narrow gap called an air gap between the stator ( static part) and the rotor ( rotating parts). The variation in the air gap mainly depends upon a variation in the diameter of the rotor because stator core is configured substantially accurately as a ring. Any variation in the air gap highly influence the performance of the generator since the resultant unbalanced magnetic pull varies widely. The wide variation in the unbalanced magnetic pull adversely affects the guide bearings performance. This variation further reduces the critical speed of the rotating system during operation of the hydrogenerator. The balancing of the rotor becomes also difficult under excited condition of the generator. Because, on account of large variation in the rotor diameter it is very difficult to balance the rotor under excited condition of the generator. The unbalanced magnetic force does also vary largely due to non uniform rotor diameter which results in non-stabilized temperature of the guide bearings and also affects the performance of the generator. OBJECTS OF THE INVENTION. It is an object of the invention to provide a device for accurate measurement of the diameter of a rotor in course of the site erection to reduce an air gap between the rotating and static components of a hydrogenerator. A further object of the invention is to provide a device for accurate measurement of the diameter of a rotor which is measured subsequent to and in correspondence to a periodical site measurement of the rim across the flat of the hydrogenerator including correction of the rim building measurement determined during the said periodical site measurement of the rim across the flat of the hydrogenator. A still further object of the invention is to provide a device for accurate measurement of the diameter of a rotor which is measured after the rim building and pole fixing. SUMMARY OF THE INVENTION. Accordingly there is provided a device for accurate measurement of the diameter of a rotor in course of site-erection to reduce an air gap between the rotating and static components of a hydrogenerator, the rotor having at least a shaft releasably coupled to a spider, a rim built around the spider by lamination of tensile sheet steel, and a plurality of poles disposed in the axial direction of the rim, the device comprising a shaft assembly detachably attachable to the spider; an arm and bush assembly having a substantially close tolerance in respect of the shaft assembly configured to be slideably insertable in the shaft assembly; a counter balance weight provided on the opposite side of the arm and bush assembly; at least two rope assemblies releasably secured on the arm and bush assembly by means of a special screw having oppositely directional threads; and a piano wire interposed in the arm of the arm and bush assembly assembled in a cover plate . The rotor mainly consists of shaft, spider, rim and poles. The shaft and the spider is coupled by a plurality of bolts and several radial keys . The rim is built around the spider by thin layers of laminations made of high tensile sheet steel, having T slots. Five part keys are provided in radial direction betweenthe spider and the rim for torque transmission. Thereafter, the poles are fitted with a plurality of taper keys in axial direction in ' T" slots made on to the rim. In view of various parts assembled at site, it is necessary to control an across flat of the rim during the rim building itself which results in an accurate and uniform message of the rotor diameter after the pole fixing. The device is of unique design which is directly mounted at the top of the spider of the generator in existing holes provided for coupling of the top shaft. A shaft assembly of the device is first fixed on to the top of the spider and thereafter, an arm and bush assembly which is made in close tolerance in respect of the shaft assembly is inserted on to the shaft assembly. A counter balance weight is provided at opposite side of the arm assembly to balance the weight of the arm assembly. Rope assemblies ( left hand and right hand ) are fitted on the bush and arm assembly with at least one special screw which has left hand thread at one end and right hand thread at other end. The rotor diameter measuring device is suitable to measure the rim across flat of the generator which measurement also plays very important role to ascertain a uniform rotor diameter because the poles of the generator are directly mounted on to the rim. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS. FIGURE : 1 : Showing an exemplary assembly of rotating and static components of a typical hydrogenerator indicating the air-gap. FIGURE: 2 : A device for accurate measurement of the diameter of the rotor diameter in assembled condition according to the present invention. FIGURE: 3 : Shaft Assembly of the device of the invention. FIGURE: 4 : Arm and bush assembly of the device according to the invention. FIGURE: 5: Rope assembly of the device of the invention. FIGURE: 6 : Special Screw for the device of the invention. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION. The rotor diameter measuring device as shown in figure-2, is used for measurement of rotor diameter of a Hydrogenerator during rotor erection at site. The device comprises a shaft assembly(1), an arm and bush assembly (2), at least one special screw (5), a cover plate (6), a balance weight (7), a piano wire (8) and a plurality of fixing screws (9). As shown in Fig. 3, the shaft assembly (1) is used for the arm and bush assembly (2) along with the balance weight (7). The shaft assembly has a shaft (17) rigidly fixed to a fixing plate ( 18) and having a plurality of holes ( 19) to releasably join with the spider (11),. As shown in figure-4, the arm and bush assembly (20 )comprising an arm (20) having a plurality of holes (H) to accommodate the piano wire (8). At least one fixing hole ( 22) is provided on the opposite side fo the arm ( 20) for fixing the balance weight (7). We Claim: 1. A device for accurate measurement of the diameter of a rotor ( 10) in course of site-erection to reduce an air gap (15) between the rotating and static components (10, 12 ) of a hydrogenerator, the rotor having at least a shaft ( 10) releasably coupled to a spider (11), a rim (23) built around the spider (11) by lamination of tensile sheet steel, and a plurality of poles (13) disposed in the axial direction of the rim (23), the device comprising a shaft assembly (1) detachably attachable to the spider (11); an arm and bush assembly (2) having a substantially close tolerance in respect of the shaft assembly (1) configured to be slideably insertable in the shaft assembly (1); a counter balance weight (7) provided on the opposite side of the arm and bush assembly (2); at least two rope assemblies (3, 4) releasably secured on the arm and bush assembly (2) by means of a special screw (5) having oppositely directional threads (RHT, LHT); and a piano wire (8) interposed in the arm (20) of the arm and bush assembly (2) assembled in a cover plate (6). 2. The device as claimed in claim 1, wherein the shaft assembly is attached to the spider (11) by means of a plurality of first bolts (9a). 3. The device as claimed in claim 1, wherein the balance weight (7) is fixed on the arm and bush assembly (2) by means of at least one second bolt (9b). 4. The device as claimed in any of the preceding claims wherein a plurality of holes (H) is provided on the arm ( 20) for insertion of the piano wire (8), the other end of the piano wire (8) having a weight ( W) being immersed in an oil bucket (OB). 5. A device for accurate measurement of the diameter of a rotor in course of site-erection to reduce an air gap between the rotating and static components of a hydrogenerator, as claimed in any of the preceding claims wherein a hydrogenator substantially as described herein and illustrated with reference to the accompanying drawings. A device for accurate measurement of the diameter of a rotor (10) in course of site-erection to reduce an air gap (15) between the rotating and static components (10,12) of a hydrogenerator, the rotor having at least a shaft (10) releasably coupled to a spider (11), a rim (23) built around the spider (11) by lamination of tensile sheet steel, and a plurality of poles (13) disposed in the axial direction of the rim (23), the device comprising a shaft assembly (1) detachably attachable to the spider (11); an arm and bush assembly (2) having a substantially close tolerance in respect of the shaft assembly (1) configured to be slideably insertable in the shaft assembly (1); a counter balance weight (7) provided on the opposite side of the arm and bush assembly (2); at least two rope assemblies (3,4) releasably secured on the arm and bush assembly (2) by means of a special screw (5) having oppositely directional threads (RHT, LHT); and a piano wire (8) interposed in the arm (20) of the arm and bush assembly (2) assembled in a cover plate (6).

Full Text

FIELD OF INVENTION.
This invention relates to a device for accurate measurement of the
diameter of a rotor in course of site errection to reduce an air gap
between the rotating and static components of a hydrogenerator.
BACKGROUND OF THE INVENTION.
The Hydrogenerators are huge in size due to their slow speed,
therefore they are manufactured as sub-assemblies to facilitate the
transportation. The sub-assemblies are assembled at site to make a
complete generator. The diameter of the rotor of the hydrogenerator
is very important since the same rotates in a narrow gap called an air
gap between the stator ( static part) and the rotor ( rotating parts).
The variation in the air gap mainly depends upon a variation in the
diameter of the rotor because stator core is configured substantially
accurately as a ring. Any variation in the air gap highly influence the
performance of the generator since the resultant unbalanced
magnetic pull varies widely. The wide variation in the unbalanced
magnetic pull adversely affects the guide bearings performance. This
variation further reduces the critical speed of the rotating system
during operation of the hydrogenerator. The balancing of the rotor
becomes also difficult under excited condition of the generator.
Because, on account of large variation in the rotor diameter it is very
difficult to balance the rotor under excited condition of the generator.
The unbalanced magnetic force does also vary largely due to non
uniform rotor diameter which results in non-stabilized temperature of
the guide bearings and also affects the performance of the generator.
OBJECTS OF THE INVENTION.
It is an object of the invention to provide a device for accurate
measurement of the diameter of a rotor in course of the site erection
to reduce an air gap between the rotating and static components of a
hydrogenerator.
A further object of the invention is to provide a device for accurate
measurement of the diameter of a rotor which is measured
subsequent to and in correspondence to a periodical site
measurement of the rim across the flat of the hydrogenerator
including correction of the rim building measurement determined
during the said periodical site measurement of the rim across the flat
of the hydrogenator.
A still further object of the invention is to provide a device for accurate
measurement of the diameter of a rotor which is measured after the
rim building and pole fixing.
SUMMARY OF THE INVENTION.
Accordingly there is provided a device for accurate measurement
of the diameter of a rotor in course of site-erection to reduce an
air gap between the rotating and static components of a
hydrogenerator, the rotor having at least a shaft releasably
coupled to a spider, a rim built around the spider by lamination of
tensile sheet steel, and a plurality of poles disposed in the axial
direction of the rim, the device comprising a shaft assembly
detachably attachable to the spider; an arm and bush assembly
having a substantially close tolerance in respect of the shaft
assembly configured to be slideably insertable in the shaft
assembly; a counter balance weight provided on the opposite side
of the arm and bush assembly; at least two rope assemblies
releasably secured on the arm and bush assembly by means of a
special screw having oppositely directional threads; and a piano
wire interposed in the arm of the arm and bush assembly
assembled in a cover plate .
The rotor mainly consists of shaft, spider, rim and poles. The shaft
and the spider is coupled by a plurality of bolts and several radial
keys . The rim is built around the spider by thin layers of
laminations made of high tensile sheet steel, having T slots. Five
part keys are provided in radial direction betweenthe spider and
the rim for torque transmission. Thereafter, the poles are fitted
with a plurality of taper keys in axial direction in ' T" slots made on
to the rim. In view of various parts assembled at site, it is
necessary to control an across flat of the rim during the rim
building itself which results in an accurate and uniform message of
the rotor diameter after the pole fixing.
The device is of unique design which is directly mounted at the top of
the spider of the generator in existing holes provided for coupling of
the top shaft. A shaft assembly of the device is first fixed on to the
top of the spider and thereafter, an arm and bush assembly which is
made in close tolerance in respect of the shaft assembly is inserted
on to the shaft assembly. A counter balance weight is provided at
opposite side of the arm assembly to balance the weight of the arm
assembly. Rope assemblies ( left hand and right hand ) are fitted on
the bush and arm assembly with at least one special screw which has
left hand thread at one end and right hand thread at other end. The
rotor diameter measuring device is suitable to measure the rim
across flat of the generator which measurement also plays very
important role to ascertain a uniform rotor diameter because the
poles of the generator are directly mounted on to the rim.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS.
FIGURE : 1 : Showing an exemplary assembly of rotating and static
components of a typical hydrogenerator indicating the air-gap.
FIGURE: 2 : A device for accurate measurement of the diameter of
the rotor diameter in assembled condition according to the present
invention.
FIGURE: 3 : Shaft Assembly of the device of the invention.
FIGURE: 4 : Arm and bush assembly of the device according to the
invention.
FIGURE: 5: Rope assembly of the device of the invention.
FIGURE: 6 : Special Screw for the device of the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF
THE INVENTION.
The rotor diameter measuring device as shown in figure-2, is used for
measurement of rotor diameter of a Hydrogenerator during rotor
erection at site. The device comprises a shaft assembly(1), an arm
and bush assembly (2), at least one special screw (5), a cover plate
(6), a balance weight (7), a piano wire (8) and a plurality of fixing
screws (9).
As shown in Fig. 3, the shaft assembly (1) is used for the arm and
bush assembly (2) along with the balance weight (7). The shaft
assembly has a shaft (17) rigidly fixed to a fixing plate ( 18) and
having a plurality of holes ( 19) to releasably join with the spider
(11),. As shown in figure-4, the arm and bush assembly
(20 )comprising an arm (20) having a plurality of holes (H) to
accommodate the piano wire (8). At least one fixing hole ( 22) is
provided on the opposite side fo the arm ( 20) for fixing the balance
weight (7).
We Claim:
1. A device for accurate measurement of the diameter of a rotor (
10) in course of site-erection to reduce an air gap (15) between
the rotating and static components (10, 12 ) of a
hydrogenerator, the rotor having at least a shaft ( 10)
releasably coupled to a spider (11), a rim (23) built around the
spider (11) by lamination of tensile sheet steel, and a plurality
of poles (13) disposed in the axial direction of the rim (23), the
device comprising a shaft assembly (1) detachably attachable
to the spider (11); an arm and bush assembly (2) having a
substantially close tolerance in respect of the shaft assembly
(1) configured to be slideably insertable in the shaft assembly
(1); a counter balance weight (7) provided on the opposite side
of the arm and bush assembly (2); at least two rope assemblies
(3, 4) releasably secured on the arm and bush assembly (2) by
means of a special screw (5) having oppositely directional
threads (RHT, LHT); and a piano wire (8) interposed in the arm
(20) of the arm and bush assembly (2) assembled in a cover
plate (6).
2. The device as claimed in claim 1, wherein the shaft assembly is
attached to the spider (11) by means of a plurality of first bolts
(9a).
3. The device as claimed in claim 1, wherein the balance weight
(7) is fixed on the arm and bush assembly (2) by means of at
least one second bolt (9b).
4. The device as claimed in any of the preceding claims wherein a
plurality of holes (H) is provided on the arm ( 20) for insertion of
the piano wire (8), the other end of the piano wire (8) having a
weight ( W) being immersed in an oil bucket (OB).
5. A device for accurate measurement of the diameter of a rotor
in course of site-erection to reduce an air gap between the
rotating and static components of a hydrogenerator, as
claimed in any of the preceding claims wherein a hydrogenator
substantially as described herein and illustrated with reference
to the accompanying drawings.

A device for accurate measurement of the diameter of a rotor (10) in course
of site-erection to reduce an air gap (15) between the rotating and static
components (10,12) of a hydrogenerator, the rotor having at least a shaft
(10) releasably coupled to a spider (11), a rim (23) built around the spider
(11) by lamination of tensile sheet steel, and a plurality of poles (13)
disposed in the axial direction of the rim (23), the device comprising a shaft
assembly (1) detachably attachable to the spider (11); an arm and bush
assembly (2) having a substantially close tolerance in respect of the shaft
assembly (1) configured to be slideably insertable in the shaft assembly (1);
a counter balance weight (7) provided on the opposite side of the arm and
bush assembly (2); at least two rope assemblies (3,4) releasably secured on
the arm and bush assembly (2) by means of a special screw (5) having
oppositely directional threads (RHT, LHT); and a piano wire (8) interposed
in the arm (20) of the arm and bush assembly (2) assembled in a cover plate
(6).

A DEVICE FOR ACCURATE MEASUREMENT OF A ROTOR DIAMETER DURING ERECTION OF HYDROGENERATORS TO REDUCE AN AIR GAP BETWEEN THE ROTATING AND STATIC COMPONENTS

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