FIELD OF INVENTION:
The present invention relates to a system and method for assembling and
dismantling of rotor in stator of turbogenerators of 600-800 MW, independent of
EOT cranes
BACKGROUND OF INVENTION
Conventionally the Rotors of 600-800 MW turbogenerators are assembled and
dismantled at test bed Rotor assembly into and dismantling from stator is
carried out with the help of E O T crane When the positions of Rotor at test bed
for its assembly into and dismantling from stator lie outside the bay of E O T
crane, the use of E O T crane is not feasible This necessitated to find a method
which enables a process of rotor assembly into and dismantling from stator of a
turbogenerator to be carried out independent of E O T crane
OBJECTS OF INVENTION
It is therefore an object of the invention to propose a system and method of
Rotor assembly into and dismantling from a stator of a turbogenerator
particularly of higher capacity of 600-800 MW independent of the EOT. crane
when its position at the test bed is outside E O.T bay

SUMMARY OF THE INVENTION
Accordingly, the invention provides a system comprising of an erection base
placed on trailer, roller trolleys, support blocks, tie rods, guide strips and guide
bars. The erection base supports the rotor at appropriate height on flat bed
trailer The centre line of stator bore is aligned with that of rotor The roller
trolley system supports and guides the rotor during its assembly and disassembly
into stator frame
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1- shows the erection base for Turbogenerator rotor
Fig 2- shows the method of insertion of a rotor into a stator frame by steps as
depicted by fig I to fig V and support details in VI to VIII.
An exemplary embodiment of the invention as depicted in the accompanying
drawings will now be explained in details However, there can be several
embodiments all of which are deemed covered by this specification
DESCRIPTION OF THE INVENTION
This invention relates to a Rotor body assembly into a stator of a turbogenerator
and dismantling from it, both being parts of a turbogenerator unit by a method
without an E 0 T crane, in a Power Plant. The system comprises of an erection
base (50) which is a fabricated steel structure and is fixed on a flat bed trailer
(51) The erection base (50) supports the rotor at appropriate height on flat bed
trailer The rotor (52) is supported on erection base (50) using roller trolleys

(26). The roller trolleys system supports and guides the rotor (52) during its
assembly and disassembly into stator frame This construction along with various
support blocks (11,12,15,16,24,32,33,34) and Tie rods (13,31) have been made
for handling a rotor for example of 800 MW Turbogenerator The same system
can be used on the same erection base by simply changing the support blocks
and Tie rods suiting the requirements of for example 600 and 660 MW
Turbogenerator rotor assembly into and dismantling from stator
For the process of rotor (52) assembly into the stator (54), the rotor (52) is
placed on the trolleys (26,27) above the trailer (51) and erection base (50) with
the help of EOT crane available in shop assembly area After rotor assembly on
trolleys, the movement of roller trolleys (26,27) is locked by using suitable
stoppers for transportation of the trailer (51) (with rotor and erection base
assembled on it) to the test bed area After trailer (51) has been brought to the
proper position in front of support pedestals (55) (for test shaft assembly) at test
bed, the stoppers are removed and erection base (50) end is locked to support
pedestals (55) ensuring plane movement surface for roller trolleys (26,27) with
rotor (52) mounted on them For the process of rotor dismantling from the
stator, first the trolley (27) for EE location is assembled on-to the rotor (52),after
it comes out of stator bore to desired extent Later after barrel portion comes out
of stator bore to desired extent, the trolley (26) for barrel location is assembled
on-to the rotor
The trailer (51) is moved by motor, which is part of it Hence trailer can be
moved from assembly area to test bed area as required
The height of the erection base (50) and roller trolleys (26) is selected to match
the axis of rotor with the centerline of stator (54) at test bed The positions of
rotor for its assembly/dismantling at test bed lies outside the E.O.T crane bay

The height of Stator axis is worked out from the stator (54) and its support
pedestals (55) at test bed and reconfirmed after assembly The height of
erection base (50) is determined considering the trailer (51) and trolley (26,27)
heights so as to achieve the same height of rotor axis As the rotor (52) is
pushed inside the stator (54), it gets supported in the stator bore at its TE
bearing location by sliding pedestal (4) and skid plate (2) The heights of sliding
pedestal (4) and skid plate (2) have been so designed that rotor axis coincides
with stator bore axis. Next rotor gets supported inside stator bore at rotor barrel
near TE retaining ring by skid shoe (5) and skid plate (2) The heights of skid
shoe (5) and skid plate (2) have been so designed that rotor axis coincides with
stator bore axis Lastly rotor (52) is supported inside the stator bore at barrel
near EE retaining ring by stack of press board shims (30) and skid plate (2) The
height of stack of press board shims (30) is kept same as that of skid shoe
(5),thus ensuring that rotor axis coincides with stator axis. Thus alignment is
ensured during the entire processes of rotor (52) assembly as well as dismantling
from the stator (54)
The structure of Erection Base (50) has a number of plate items (41,42,43,44)
welded suitably with one another Two top plates (42) of the erection base are
provided with guide strips (48) for guiding the movement of roller trolleys (26).
The longitudinal plates (41,47) welded with transverse plates (44) are provided
with stiffeners (45,46) to support the load of moving rotor (52) and transverse
forces during short distance transportation respectively The height of erection
base (50) and roller trolleys (26) is selected to match the axis of rotor (52) with
the centerline of stator (54) at test bed. The stress analysis of erection base (50)
is carried out for conditions of moving load of rotor during its assembly and
dismantling with stator as well as those of short distance transportation in shop
blocks. The design of erection base (50) has been developed and optimized
using Finite Element Analysis technique. Different Design variants have been
analyzed using parameters like thickness and width of plates to optimise the

design Adequate factor of safety has been ensured with respect to the yield
strength of the material under all loading condition
Guiding bars (3) are provided on top of Erection base (50) as well as above
excitor support pedestals (55) at test bed to ensure the movement of rotor (52)
in axial direction only Trolleys (27) for EE (exciter end) Journal has a base plate
(22) on top of it which is assembled with two support blocks (15,24) and a
channel (25) by tie rods (13) at two end allowing the EE Journal to seat Trolleys
(26) for Rotor barrel has a Base plate (8) which is assembled with two support
blocks (12) and a channel (10) by tie rods (31)
The sliding pedestal (4) is an assembly of fabricated steel body having 6mm
thick PTFE sheet at bottom Skid plate (2) is also an assembly of smoothly
machined steel plate having PVC sheet at bottom PTFE sheet of sliding pedestal
(4) slides over the greased steel surface of skid plate (2) with a very low
coefficient of friction, thus reducing the effort required for push/pull using the
pulling machine Similarly skid shoe (5) has PTFE sheet at its bottom for sliding
over skid plate (2)
The method of rotor (52) assembly into a stator (54) begins with the rotor (52)
being assembled on top of erection base (50) and trailer (51) with roller trolleys
(26,27) using base plates (8,22), tie rods (13,31), support blocks (11,12,15),
channels (10,25) at barrel center and exciter end (EE) bearing positions Also
rotor (52) is assembled with sliding pedestal (4) assembly at bearing position on
turbine end (TE) Trolleys (26,27) are put at EE Journal and Rotor barrel position
(section A-A and B-B) Trailer (51) is brought adjacent to supporting pedestal
(55) and trailer height is adjusted to align top surfaces of pedestal (55) and
erection base (50). Then guide bars (3) is aligned on Pedestal (55) top surface.
Blower covering is then removed but the blower protection ring is left on blower
protection rim (53) Care is taken that at no time any load comes on either of

retaining rings which are end-supported and enclose rotor winding overhang
parts or on compressor blades The position of these support points are so
selected that during the movement of rotor (52) it always remains supported at
least at two places, even when some of these supports are removed or
disassembled before pushing rotor (52) further inside the stator (54) The skid
plate (2) and Boards (9) are placed and Grease (23) is applied on skid plate (2),
sliding pedestal (4) and skid shoe (5) to minimize the friction. End shield upper
halves, shaft seals and Bearings of both turbine end (TE) and exciter end (EE)
are not assembled before starting the rotor assembly process End shield lower
halves are lowered from normal position and kept hanging from sides of support
pedestal (55) at test bed by specially designed brackets Rotor (52) is gradually
pushed towards stator (54) by using pulling machine (38) with wire rope
anchored from stator (54) After some movement, sliding pedestal (4) supports
rotor (52) inside stator (54) bore. After roller trolley (26) gets free of support
from exciter support pedestals (55), it is disassembled During the movement of
rotor barrel (52) inside the stator bore (54), the rotor barrel is supported at TE
by inserting skid shoe (5) by pulling with polyster cords drawn towards TE just
after the retaining ring TE has entered inside stator bore (54). A stack of Press
boards (30) provided with strings for guiding placement and removal, is inserted
after travel of half length of rotor (52) barrel inside the stator bore (54) and an
additional stack of press boards (30) is inserted just before entry of retaining ring
EE in stator bore (54) on Exciter side (EE). End shield lower half TE is lifted to its
normal position after TE coupling flange of rotor (52) comes out clear of end
shield TE The rotor (52) is supported by assembling rotor insertion cross beam
TE (6) with end shield TE. Skid shoe (5) on TE is removed and shaft seal TE and
bearing TE are assembled. Next end shield lower half EE is lifted to its normal
position and rotor (52) is supported on rotor insertion cross beam EE (7)
assembled with end shield lower half EE Press boards (30) are removed Skid
plate (2) is removed after turning it around rotor (52) to upper side of bore
Press boards (9) is also removed Then Bearing lower half TE is placed on Rotor

Journal TE lifting the rotor (52) using cross beams (6,7). Similarly with rotor (52)
lifted using cross beam EE (7), bearing lower half EE is placed on rotor journal
EE Cross-beams (6,7) are removed. Rotor (52) is then aligned and coupled with
turbine rotor
For rotor dismantling, Generator rotor (52) is de-coupled from turbine rotor End
shield upper halves are removed Rotor (52) is supported on rotor insertion cross
beams TE and EE (6,7) and bearings and shaft seals TE and EE are removed
Skid plate (2) is inserted in the stator bore (54) above rotor (52) and turned
around rotor (52) to position below rotor (52) Skid shoe (5) is inserted at TE
just inside retaining ring TE and stack of press boards (30) is inserted just inside
retaining ring EE. End shield EE is lowered and supported by special brackets
(16) from intermediate support of exciter support pedestal (55) at test bed
Rotor insertion cross beam EE (7) is removed. End shield lower half TE is
lowered and supported by special brackets (1) from intermediate support of
pedestals at test bed. Rotor insertion cross beam TE (6) is removed. Sliding
pedestal (4) is assembled on rotor (52) at TE bearing location. Rotor is gradually
pulled out from stator (54) using pulling machine (38) with wire rope Trolley
(27) is assembled on rotor (52) at position of bearing EE (Section B-B) after it is
clear of stator (54) On further pulling rotor (52) gets supported by this trolley
(27) on intermediate support of support pedestal (55) at test bed and skid shoe
(5) is taken out As middle portion of rotor barrel (52) comes clear of stator (54),
Trolley (26) is assembled on rotor (52) in that portion (Section A-A). Rotor (52)
gets supported by this trolley (26) on intermediate support of pedestal (55) at
test bed before sliding pedestal (4) comes out from Stator bore (54). Sliding
pedestal (4) is disassembled. After more pulling, rotor (52) with trolleys (26,27)
gets transferred into Erection base (50) and trailor (51) for further transportation
of maintenance bay

WE CLAIM
1. A system for assembling and dismantling a rotor and stator of large
turbogenerators upto 800 MW independent of EOT cranes comprising:
a trailer with an erection base (50) mounted there on for moving trolleys
(26,27) carrying the rotor (52) towards or away from the stator (54); and
a pulling device consisting of a pulling machine (38) guide pulley (14) and
wire ropes for assembling the rotor (52) into the stator (54) or for
dismantling the rotor (52) from the stator (54);
2. The system as claimed in claim 1, wherein the height of said roller trolleys
(26,27) on said erection base (50) is adjustable for alignment of rotor and
stator axes
3 The system as claimed in claim 1, wherein the erection base is a
fabricated structure of steel plates (41,42,43,44).
4. The system as claimed in claim 1, wherein the two top plates of the
erection base (50) are provided with guide strips (48) for the movement
of the roller trolleys (26,27).
5. The system as claimed in claim 1, wherein the erection base having the
longitudinal and transverse plates (41,47) is welded and provided with
stiffeners (45,46) for rigidity.
6. The system as claimed in claim 1, wherein the trolleys (26,27) is guided
by guide bars (3) provided on support pedestal (55) at the entry point to
the stator

7 The system as claimed in claim 1, wherein roller trolleys (26,27) having
base plates (8,22) on the top is fixed with support blocks (12,15,24) and
channels (10,25) by tie rods (13,31).
8. The system as claimed in claim 1, wherein the rotor (52) slides on skid
plate (2) is placed on stator (54).
9. The system as claimed in claim 1, wherein the rotor (52) is supported by
skid shoe (5) and a plurality of press boards (30,9).
10. The system as claimed in claim 1, wherein a plurality of cross beams (6,7)
are provided at two ends (TE and EE) for lifting the rotor (52).
11 A method for assembling of rotor in stator of turbogenerators in the range
of 600-800 MW independent of EOT cranes comprising:
an erection base (50) being mounted on trailer (51) moves the rotor (52)
being held on plurality of trolleys (26,27) towards or away from the stator (54);
the height of the erection base (50) and roller trolleys (26,27) is
maintained to match the axis of rotor (52) with the centerline of stator (54) at
test bed;
a pulling machine (38), guide pulley (14) and wire ropes pulls the rotor
(52) for assembling into the stator (54) or for dismantling the rotor (52) from
stator (54).

12 A method as claimed in claim 11, wherein the sliding pedestal (4), skid
shoe (5) and press boards provide support to the moving rotor (52) when
the retaining ring (TE) enters the stator bore (54)
13. A method as claimed in claim 11, wherein the trolley (26) is disassembled
when it gets free of support from support pedestal (59).
14.A method as claimed in claim 11, wherein press boards (30) are provided
below the rotor (52) reaching half of its length into the stator bore.
15. A method as claimed in claim 11, wherein additional press boards (30) are
provided before entry of retaining ring (EE) in stator bore on exciter side.
16 A method as claimed in claim 11, wherein the trolley (27) positioned on
bearing (EE) is removed when coming out from support pedestals (55).
17.A method as claimed in claim 11, wherein the Rotor (52) is assembled
with end shield lower half TE, shaft seal and bearing TE when the rotor
(52) comes out clear of end shield TE
18. A method as claimed in claim 11, wherein end shield lower half EE, shaft
seal EE, bearing EE are assembled after press boards (30), skid plate (2)
and cross beams (6,7) are removed, and the rotor (52) is aligned and
coupled with turbine rotor.
19. A method for dismantling of rotor (52) from stator (54) of turbogenerators
in the range of 600-800 MW independent of EOT cranes comprising:
a generator rotor being decoupled from Turbine rotor;
skid shoe (5), skid plate (2), press boards (30) being inserted;

end shields, shaft seals, bearings being removed,
trolleys (26,27), sliding pedestal (4), support pedestal (55) being
assembled; and
the rotor (52) being dismantled by the pulling machine (38), guide pulley
(14) and wire ropes;
20. A method as claimed in claim 19, wherein the rotor being clear of stator
for half the length, the said rotor (52) is supported by supporting pedestal
(55), the sliding pedestal (4) being removed, and the rotor (52) with
trolleys (26,27) is transferred into erection base (50).

ABSTRACT

SYSTEM AND METHOD FOR ASSEMBLING/DISMANTLING OF ROTOR IN
STATOR OF TURBOGENERATORS OF 600-800 MW INDEPENDENT OF
E.O.T. CRANES.
The invention relates to a system and method for assembling and
dismantling a rotor and stator of large turbogenerators upto 800 MW at test bed
independent of E O.T. cranes. The system comprises of a trailer (51) having an
erection base (50) mounted thereon moves trolleys (26,27) carrying a rotor (52)
towards or away from the stator and a pulling device consisting of a pulling
machine (30), guide pulley (14) and wire ropes pulls the rotor into the stator for
assembling and away from stator for dismantling after maintaining the alignment
of rotor and stator axes. The erection base having longitudinal and transverse
plates (41,47) welded and is provided with stiffeners (45,46) for rigidity. Sliding
pedestal (4), skid shoe, press boards (9,30) and a supporting pedestal (59)
provides support to the moving rotor (52).