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“The Right to Information, The Right to Live”
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है”
ह”
ह
IS 12800-1 (1993): Guidelines for selection of turbines,
preliminary dimensioning and layout of surface
hydro-electric power houses, Part 1: Medium and large power
houses [WRD 15: Hydroelectric Power House Structures]

4. IS 12800 (‘Part 1 ) : 1993
Indian Standard
GUIDELTNBSFOR SELECTJONOFTURBINES,
PRELIMINARYDIMENSIONINGAND
LAYOUTOFSURFACEHYDRO-ELECTRIC
POWERHOUSES
PART 1 MEDIUM AND LARGE POWER HOUSES
UDC 627.85 : 621.224~2
o BIS 1993
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI I 10002
August 1993 Price Group 8
( Reaffirmed 2003 )

5. Hydro-electric Power House Structures Sectional Committee, RVD 15
FOREWORD
This Indian Standard ( Part 1 ) was adopted by the Bureau of Indian Standards, after the draft finalized
by the Hydro-electric Power House Structures Sectional Committee had been approved by the River
Valley Division Council.
So far as to generate electrical energy from Hydroelectric Power Houses, Selection of Turbines,
Preliminary Dimensioning and Layout is necessary in designing of such Power Houses, requirement
will be different from large, medium and micro ( small ) Power Houses. Requirements are, therefore,
laid down separately for large and medium Power Houses and small Power Houses. This standard is,
therefore, formulated into three parts - Part 1 covering Medium and Large Power Houses, Part 2
covering Storage Power Houses and Part 3 Mini and Micro Power Houses.
Guidelines covered in this standard are applicable after fixing the data with regard to the capacity,
type, number of units and discharges. Departure from the guidelines will be necessary to meet such
special requirements and condition of individual site based on judgement and experience. _
For the purpose of deciding whether a particular requirement of this standard is complied with, the
final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in
accordance with IS 2 : 1960 <Rules for rounding off numerical values ( revised )‘. The number of
significant places retained in the rounded off value should be the same as that of the specified value in
this standard.

6. IS 12800 ( Part 1 ) : 1993
Indian Standard
GUIDELINESFORSELECTION OFTURBINES,
PRELIMINARY DIMENSIONING AND
LAYOUTOFSURFACEHYDRO-ELECTRIC
POWER HOUSES
PART 1 MEDIUM AND LARGE POWER HOUSES
1 SCOPE
This standard (Part 1) lays down guidelines
for preliminary dimensioning for surface hydro-
electric power houses with reaction turbines
having vertical shaft arrangement.
NOTE - These guidelines will generally apply to
unit capacities from 5 MW to 500 MW.
2 REFERENCES
The Indian Standards listed below are necessary
adjuncts to this standard:
IS No.
4410
( Part 10 ) : 1988
5496 : 1969
7418 : 1991
7326
( Part 1 ) : 1992
12837 : 1989
7332
( Fart 1 ) : 1991
Title
Glossary of terms relating
to river valley projects :
Part 10 Hydro-electric
power station including
water conductor system
(first revision )
Guide for preliminary
dimensioning and layout of
elbow type draft tubes for
surface hydel power stations
Criteria for design o’ spiral
casing ( concrete and steel )
(first revision )
Penstock and turbine inlet
butterfly valves for hydro-
power stations and systems:
Part 1 Criteria for structural
and hydraulic design
Hydraulic turbines for
medium and large hydro-
electric powel houses - -
Guidclincs for selection
Spherical valves for hydro-
power stations and systems:
Part 1 Criteria for structural
and hydraulic design
3 TERMINOLOGY
3.0 For the purpose of this standard, the defini-
tionsgiven in IS 4410 ( Part IO ) : 1988, IS 7418 :
1991 and following should apply.
3.1 Specific Speed ( n, )
It is the speed in r.p.m. at which a turbine of
homologous design would operate, if the runner
were reduced to a size which would develop one
metric horse power under one metre head. tt is
given by:
where
IZS=
Yl=
P=
H=
specific speed of turbine in revolutions/
minute,
rated speed of turbine in revolutions/
minute,
turbine output in kW, and
rated head in metres.
3.2 Minimum Tail Water Level
It is the water level in the tail race at the exit
end of the draft tube corresponding to a
discharge required to run one machine at no
load.
4 MAlN PARAMETERS OF TURBINE
4.1 Type of Turbine
The selection of type of turbine should be made
in accordance with TS 12837 : 1989.
4.2 Speed
4.2.1 Rated head and output per machine being
known, suitable speeds rrom economical
considerations may be decided in consultation
with the manufacturer.
4.2.2 Alternatively, speed can be detcrmi~~etl by
the following steps.
4.2.2.1 Determine trial specific speed by Fig. I
corresponding to available rated head of site.
4.2.2.2 After ascertaining trial specific speed as
mentioned in the foregoing para. trial synchro-
110~sspeed/rotational speed II’ can bc computed
from the following formula:

7. .
IS 12800 ( Part 1 ) : 1993
where
II,’ = trial specific speed.
: 000
4.2.3 After
mentioned
determined
4.2.4 If on
determining the rated speed as
above, the specific speed can be
by the formula given in 3.1.
account of heavy silt abrasion is
.
apprehended then a lower value may be
adopted.
4.3 Turbine Setting
600
500
400
* 200
w
g
z 100
9
I
.
2
s!
e 50
G
(r 40
30
20
10
50 100 200 300 400 500 1cm
SPECIFIC SPEED (ns~
FIG. 1 REL.~TIONSHIPBETWEENSPECIFICSPBED
AND RATBDHEAD
4.2.2.3 The rotational/synchronous/rated speed
of the turbine in revolutions per minute is
determined from the following formula:*
60 x f
Hated speed in r.p.m, II - ~---
P
4.3.1 In reaction turbines, the setting of turbine
with respect of minimum tail water level should
be fixed from the consideration of cavitation.
The suction height of distributor centre line
above the minimum tail water level can be
determined from the following formula:
where
Ha s
Hb =
H, =
0=
H, < H,, -- oH - Hv
Suction head in metres;
Barometric pressure in metres of
water column;
Vapour pressure; and
( In the absence of specific data the
value of Hb - H, can be determined
from Fig. 2 for a given altitude above
mean sea level and for a given tempera-
ture which is generally taken as 30°C. )
Thoma’s cavitation coefficient, which
can be obtained from Fig. 3A and
Fig. 3B.
The positive value of Hs indicates that the
centre line of the distributor may be placed
up to Ha metres above the minimum tail water
level. The negative value of Hs indicates that
the centre line of the distributor is to be placed
at an elevation of at least HB metres below
minimum tail water level.
where
.f = frequency ia cycles per second ( In
$ a.5
Indian Power systems, frequency - %
50 cycles per second ), and 5
a
]J - number of pairs of pOkS.
The selection of rated speed by the above ‘;
formula is subject lo the following considera- $ 7
lions:
a)
h)
An even number of pairs of poles should
be preferred for the generator, through
standard generators with odd number of
-; 65
6
pairs of poles are also available; and z! g
If the head is expected to vary less than
~~~~;~
- r 7 7. <1
10% from the design head, the next ALflTClDE
ABOVE
SEA LEVEL (metres)
greater speed should be chosen. A head
varying in excess of 10% from the design
FIG. 2 HEIGHT OF BAROMETRIC:
WATERCOLUMN
head suggests the next lower speed.
AT DIFFERENTTEMPERATURES
OFWATERAND
ALTITuDBS Anov~ SRAL~VFI.
2

8. 600
60
IS 12800 ( Part 1 ) : 1993
':
04 006 008 01 02 03
THOMA’S COEFFICIENT
FIG. 3A THOMA’S COEFFICIENT
AT DIFFBRL~NT
SPECIFIC
SPEEDFORFRANCISTURBINE
ooc
800
600
500
400
0.3 04 05 06 07 08 09 10
THOMAS COEFFICIENT (0 1
FIG. 3B THOMA’S COEFFICIENT
FORDIPFBRBNTSPECIFICSPEEDFORKAPLANTURBINES
4.3.2 In case the turbine setting, to have a
cavitation free runner at a given specific speed,
is found to be very low resulting in uneconomi-
cal construction of power house, the specific
speed may be reduced by decreasing the speed
of rotation.
4.4 Runner
4.4.1 The runner discharge diameter LJ~ for
Francis turbine and runner diameter & for
Kaplan turbine ( shown in Fig. 3 ) are both
determined by the peripheral velocity cocffi-
cient K,, which is defined a’s:
x D I18
where D is & ia case of Francis turbine and D,:
in case of Kaplan turbine.
The relationship between specific speed ( 11,) of
machine and peripheral vclocit>’ coefficient ( KU)
3
is shown in Fig. 5 for Kaplan turbines and in
Fig. 6 for Francis turbines.
4.4.2 The other runner dimensions of Francis
turbine indicated in Fig. 4 may be obtained
with respect to the diameter D3 and specific
speed 17~ from the curves shown in Fig. 7.
4.5 Spiral Casing
4.5.1 Mefallic Spiroi Ccrsitrg
Metallic spiral casing should bc ur;ecl for gross
heads generally above 30 metrcs. The major
dimensions of the spiral casing indicated in
Fig. 8 may be obtained as a function of YIP,
refcrrcd to runner diameter I>, or D!: from the
curves shown in Fig. 9 and 10.
Concrete spiral casing shouid bc designed in
accordance with lS 7418 : 1991. ‘l‘hc radius I( OF
the inlet portion and the l;idth B of the open
portion of the casing, indicxtcd in Fig. 1I can

9. X$ 12800 ( Part 1 ) : 1993
KAPLAN -lbRBINE
FIG. 4 TYPICAL SHAPESOF REACTION TURBINE RUNNERS
22
2.0
18
1.6
14
1.2
300 400 500 fml 7OCJ 800 900 1000 11x
SPECIFIC SPEED rli
FIG. 5 RELATIONSHIP BETWEEN SPECIFIC SPEED( nH) AND PBRIPHERAL VHL()~~TY
COEFFICIENTk',,
FOR KAPLIN TURBINE

10. IS 12800 ( Part 1 ) : 1993
06
0 100 20Q 300 400’ 500
SPECIFIC SPEED ns
FIG. 6 RELATIONSHIP BETWBEN SPECIFIC SPBED ( ns ) AND PBRIPHBRALVBLOCITY
COEFFICIENTK, FOR FRANCIS TURBINE
2.0
18
16
14
12
10
0.8
0.6
0.4
02
0.0
50 150 200 250
SPECIFIC SPEED n,
FIG. 7 RUNNBR DIMBNSIONS WITH RESPWT TO THE DIAMETER L+ AND SPBCIFIC SPEED
FOR FRANCIS TURBINE
5

11. IS 12800 ( Part 1 ) : 1993
I-
++----I :
D-1 - 5-J
FIG. 8 MAJORDIMENSIONS
OFTHE SPIRAL
CASING
be determined by the following formula:
R = 1.6 D1, and
B = R + KD1.
where
K = 0.95 for # = 180” to 200”, and
K = 1.1 for 4 = 200” to 225’.
The equation of semispiral is given below:
where
P=
KI, K, =
The values
P = K1 - KI -8’
radius of curvature of the semi-
spiral at an angle 8 in radians, and
constants.
of constants K1 and K, can be
evaluated by the following conditions:
P = R at 0 = O”, and
P- 0.5 x stayvane outside diameter at
0 = 4.
Stayvane outside diameter is ‘F’ as determined
from Fig. 10.
4.6 Draft Tube
Major dimensions of the draft tube are given in FIG, 9 SPIRAL CASING DINENSIONS WII II
Fig. 12 and should be determined in accordance
with IS 5496 : 1969.
RESPECTTO RUNNER DIAMETER
D, OR I),( AND
SPECIFIC:
SPEED 11~
6
5 MAIN PARAMETERS OF HYDRO-
GENERATORS
5.1 Air Gap Diameter ( D, )
5.1.1 The air gap diameter ( see Fig. 13 and 14 )
can be determined from the following criteria:
a)
‘3
The air gap diameter D, should be large
enough to allow the turbine runner top
cover to pass through the stator bore.
This condition is likely to be limiting
only with large Kaplan turbines of low
speed where a clearance of at least 5 cm
should be allowed.
The maximum value of air gap diameter
D, is governed by the maximum permissi-
ble stresses in the rotor parts and rim and
these are directly linked with the peri-
pheral velocity on runaway speed.
Assuming the runaway ratio to be 1.85 to
2.3 for Francis turbine and 2.3 to 3.2 for
Kaplan turbine ( higher speed ratio for
lower head ) the value of maximum
peripheral rotor velocity V, at rated
speed can be read from Fig. 15.
& 2.6
m 2.4
g 22
5 20
5 16
5 16
I 1.4
0
: 12
5 10
2 0.8
u OGL A I I / I
a 50 100 150 200 2% 300 350
03
SPECIFIC SPEtD 71s
w 12
0,
5
10
4' 08
cc
7 06
14
50 100 150 200 250 'cjr, :;,r)
SPFCIFIC SPEED -:

12. This curve relates to sheet steels having a yield
point of 525 N/mm*. For better quality steels
peripheral velocity be increased in direct ratio
of yield strength. The peripheral velocity thus
settled, the value of D, in metres can be
obtained from the following formula:
&=60x v,
TE 12
where
v, = maximum peripheral velocity in
metreslsec, and
n = rated speed of machine in r.p.m.
a
& 3.0
2 2.8
2 2.6
L 2.4
6 2.2
z! 2.0
i 1.8
ii
1.6
4
1.4
ii
1.2
a
1.0
ul 50 100 150 200 250 300 350
SPECIFIC SPEED ns
r
r:
8 1.1
0)
g 0.9
1.0
L
g 0.7
0.8
zi 0.6
I
ii 0.5
; 0.4
0 03
-f
$ 0.2
I I I
n
U? 50 100 150 200 250 300 350
SPECIFIC SPEED ns
FIG. 10 SPIRAL CASING DIMENSIONS WITH
RESPECT
TO RUNNER DIAMETER& OR Dn AND
SPECIFIC
SPEEDns
FIG. 11 CONCRETE
SPIRALCASING
IS 12800 ( Part 1 ) : 1993
1 OF GUIDE APPARATUS
----_-__
-+-----I
H = Depth of the draft tube
L = Length of the draft tube
B = Width of the draft tube
FIG. 12 MAJOR DIMENSIONSOF DRAFTTUBE
5.2 Outer Core Diameter ( D, )
Outer core diameter Do of the stator ( see Fig.
13 and 14 ) can be determined by the following
formula:
D,, = D, (1 +-$-)metres
where
p = number of pairs of poles.
FIG. 13 SUSPENDED
TYPECONSTRUCTION
7

13. .
IS 12800 ( Part 1) : 1993
i i
, I
I I
FIG. 14 UMBRELLA/SEMI-UMBRELLA TYPE
CONSTRUCTION
5.3 Stator Frame Diameter ( Df )
5.3.1 Stator frame diameter Df ( see Fig. 13
and 14 ) ( across flat dimension in case of
polygonal shape ) can be determined by adding
1.2 metres to the outer core diameter, D, i.e.
Df = ( Do + 1.2) metres.
can be determined by adding 2.3 to 2.8 metres
IO the stator frame across flat dimensions ( Df )
i.e.
D, = ( D, + 2.3 to 2.8 ) metres
= ( D, + 3-S to 4.0 ) metres
Db = ( De + l-6 to 2.0 ) metres
= ( D, + 2.8 to 3.2 ) metres
5.5 Core Length of Stator ( L, )
5.5.1 Core length of stator L, ( see Fig. 13
and 14 ) can be determined by the following
formula:
where
W = Rated KVA of machine, and
K, = Output coefficient to be determined
from Fig. 16.
5.6 Leogth of Stator Frame ( Lr )
Length of stator frame Lf ( see Fig. 13 and 14 )
can be determined by adding I.5 to I.6 metres
to the length of stator core i.e.
Lt = ( L, + 1.5 to 1.6 ) metres.
5.7 Height of Load Bearing Bracket ( h, )
5.7.1 Height of load bearing bracket Hj
Csee Fig. 13 and 14 ) can be determined by the
following formula:
5.4 Inner Diameter of Generator Barrel ( DI, )
5.4.1 Inner diameter ( DI, ) of generator barrel
( see Fig. 13 and 14 - Inner dimensions across
aat faces in case of polygonal shaped barrel )
__-.
hj = K V’ Df for suspended type construe-
tion, and
II~= K 4 Dgfor umbrella type construc-
tion.
NUMaER OF PAIRS OF POLES (P,
FIG. 15 MAXIMUM PEIUPHBRAL
ROTOR VELOCI,~YIf, AT RATED SITED
8

14. where
K = 0.65 for load of less than 50 tonnes per
arm of the bracket,
KG 0.75 for load of 50 to 100 tonnes per
arm of the bracket, and
K I 0.85 for a load of 100 tonnes and
above per arm of the bracket.
Load per arm of the bracket to be determined
as given hereunder.
5.8 Number of Arms of Brackets
The number of the arms of the bracket are to
be decided on the basis of the total load on the
thrust bearing that is maximum hydraulic thrust
of the turbine runner and weight of rotating
parts. Generally 4 to 8 arms of the bracket are
taken.
5.9 Axial Hydraulic Thrust
Axial hydraulic thrust P,< on ihe turbine runner
may be determined by the following formula:
PH =
where
K=
D1 =
H max =
K D,‘J H,,, in tonnes.
a constant to be determined from
Fig. 17A and Fig. 17B,
inlet diameter of runner in metres,
and
maximum head in metres.
IS 12800 ( Part 1 ) : 3993
5.10 Weight of Generator Rotor
Weight W?: of generator rotor in relation with
air gap diameter DR and active core length LC
can be determined from Fig 18.
5.11 Weight of Turbine Runner
Weight of turbine runner can be determined
from Fig. 19A and 19B.
5.12 Weight of machine rotating parts comprises
the weights of rotor and runner. Total axial
load for use in the determination of height and
number of load bearing brackets should
comprise the hydraulic thrust and the weights
of rotor and runner.
6 OVERALL DIMENSIONS OF POWER
HOUSE
6.1 The overall dimensions of power house
mainly depend upon the following:
a) Overall dimensions of the turbine, draft
tube and scroll-case;
b) Overall dimensions of the generator;
c) Number of units in the power house; 2nd
d) Size of the erection bay.
NOTE -- Provision for inlel valve, erection 01‘ ,otor
and untanking of transformers should be made in
such a vay that the space required is minimum with-
out impairing the operational and maintenance
requirements.
OUTPUT COEFFICIENT, l<o
171~;. 16 DETERMINATION
OF OUTPUTCOBFFICIENT

15. IS 12800 ( Part 1 ) : 1993
0.40
0 35
0.30
0.25
0.20
0.15
0.10
0 05
0
50 100 150 200 250 300 350
SPECIFIC SPEED (n s)
FIG. 17A DETERMINATION OF AXIAL HYDRAULIC THRUST COEFFICIENT FOR FRANCIS TURBINE
I -
i-
)L
1 I
FIG. 17B DETERMIXATION OF AXIAL HYDRAULIC TI~RIJS~.COEFPXCIENT
FOR KAPLAN T~JRRINH

16. IS 12800 ( Part 1 ) : 1993
2 4 6 8 10 12 14 it‘
AIR GAP DIAMETER (D Q ) IN METRES
FIG. 18 WEIGHT DkI OF GENERATOR ROTOR IN RELATION WITH AIR GAP DIAMETER D, AND
ACTIVE CORBLENGTH L,
6.2 Length of Power House axis of the machine. For determining the outer
It depends upon the unit spacing, length of
erection bay and the length required for the
E.O.T. crane to handle the last unit.
6.2.1 Unit Spacing
For determining the distance between the
centre lines of the successive units? a plan
showing the overall dimensions of the spiral
casing, the draft-tube and the hydro-generator
should be drawn with respect to the vertical
dimensions of the generator barrel,- the inner
diameter of the generator barrel may be increa-
sed by 0.5 to 15 m depending upon the size of
the machine. A clearance of l-5 to 2.0 m should
be added on either side of the extremities of
the above drawn figures to determine the unit
spacing. These clearances should be such that
a concrete thickness on either side of scroll
case should be at least 2.0 to 2.5 m in case of
concrete scroll cases and 1.0 IO I.5 m in
case of fully-embedded steel scroll cases.
I I J (1 5 tl I a
RUNNER DIAMETER (Dl) IN METRES
FIG. 19A RELATIONSHIPkk'WREN RUNNERWI-IGHT AND RUNNER DIAMETER FOR
FRANCISTURBINE
11

17. IS 12800 ( Part 1 ) : 1993
C
1 2 3 4 5 6 7 6
RUNNER DIAMETER (Dl) IN METRES
FIG. 19B RBLATIONSHIPBETWBBN
RUNNERWEIGHT ANDRUNNBRDIAMETERFORKAPLAN TURBINES
6.2.2 The length of erection bay may be taken On the upstream side provision should be made
as 1.0 to 1.5 times the unit bay size as per for the following:
erection requirements.
62.3 The total length L of the power houses
can then be determined as follows:
L = No x ( unit spacing ) + LB + K
where
a)
b)
cl
N,, = Number of units,
L, = Length of erection bay, and
K = Length required for the E.O.T. crane
to handle the last unit. Depending
upon the number and size of the E.O.T.
crane, this length is usually 3.0 to
5.0 metres.
d)
e)
NOTE - IZ)lleto special topographical tail water
conditions it may become necessary to provide addi-
tionzl unloading bay at different levels.
6.3 Width of Power House Super structure
A clearance of about I.5 to 2-O m for
concrete the upstream of scroll case;
A gallery of 1.5 to 2~0 m width for
approaching the draft tube manhole;
In case the main inlet valve is also
accommodated in the power house, a valve
pit of appropriate size should have to be
provided as per IS 7326 ( Part 1 ) : 1992
and IS 7332 ( Part 1 ) : 1991;
A clearance of about l-5 to 2.0 metres
for pressure relief valve in the scroll case,
if required; and
The spaces as indicated against item (a)
to (d) are supposed to be sufficient for
accommodating the auxiliary equipment
also but may have to be reviewed con-
sidering the layout of essential equipment
and operational requirements.
For determining the width of the power house
6.3.1 The inlet valve gallery, if provided, can be
superstructure, the overall dimensions of the
utilized for approaching the draft-tube man-hole
spiral casing and the hydrogenerator may be
also and hence no separate gallery is needed for
drawn with respect to the vertical axis of the
this purpose.
machine. Superstructure columns should be 6.3.2 The cirteria laid down in 6.3 gives the
clear of the downstream extremities of the
above drawn figure by about 2.0 to 2.5 metres.
internal width of the Power Honse ( exclutiing
column width ).
12

18. .
6.4 Height of Power House
6.4.1 The height of power house from the
bottom of the draft-tube to the centre line of
the spiral casing H, ( see Fig. 20 ), can be
determined in accordance with IS 5496 : 1969.
The thickness of the concrete below the lowest
point of draft-tube may be taken from 1.0 to
2.0 m depending upon the type of foundation
strata, backfill conditions and size of the power
house.
6.4.2 The height of power house from the
centre line of the spiral-casing up to the top of
the generator H2 ( see Fig. 20 ) can be determi-
ned, as follows:
H, = Lt + hj + K
Lt and hj have been defined in 5.6 and 5.7.1
respectively. The value of K may be taken as
5.5 to 7.0 depending upon the size of the
machine.
FIG. 20 CROSSSB~TIONTHROUGH GENERATING
UNIT
IS 12800 ( Part 1) : 1993
6.4.3 The height of the machine hall above the
top bracket of the generator depends upon the
E.O.T. crane hook level and the correspondmg
E.O.T. crane rail level, and the clearance
required between the ceiling and the top of the
crane. Further the height should depend upon
the height of the service bay floor from where
the equipment is to be handled.
6.4.3.1 The E.O.T. crane hook level and the
corresponding crane rail level are determined
by providing adequate clearance for the
following cases:
a) Hauling moving major items of equip-
ment viz. turbine runners assembly, rotor
assembly and even entire generator
stator.
b) Hauling the main transformer with
bushing into the erection bay under
E.O.T. crane girder.
c) Clearance required for untaking
transformers.
d) Unloading of largest package from
trailors. A height of 7 to 8.5 metres
tween the top erection bay floor and
highest hook level may be sufficient.
the
of
the
be-
the
6.4.3.2 The height of the power house ceiling
above the highest level of the E.O.T. crane
hook may generally vary from 4 to 6.5 m depen-
ding upon the width of the power house super-
structure and capacity of E.O.T. crane. Keeping
a clearance of O-3 metre between the highest
part of the gantry crane and the ceiling of the
power house. A typical example for calculating
the overall dimensions of the power house is
given in Annex A.
ANNEX A
( Clause 6.4.3.2 )
TYPICAL EXAMPLE FOR CALCULATING THE OVERALL DIMENSIONS OF
POWER HOUSE
A-l DATA
Type of Machine
Total Number of Machines
Unit Capacity
Maximum Head
Rated Head
Minimum Head
Francis Turbine
4
100 MW
105 111
100 m
75 m
13
Barometric Pr-essure at Power IO m
House site
Vapour Pressure at Power 0.4 m
House site
Power Factor 0.9
A-2 SYNCHRONOUS SPEED
From Fig. 1, specific speed of machine may
be taken as 205.

19. .
IS 12800 ( Part 1 ) : 1993
Synchronous speed of machine
ns . Hbl4
=L/ P x l-358-
[ Same as adopted by IS 12800 ( Part 2) : 1989 1.
where
n, = 205 r.p.m.,
H = 100 m, and
P= 100 xl OOOkW
:. Trial synchronous speed machine
205 x 1005/r
- v 106 x 1.358
= 176 r.p.m.
Synchronous speed for 18 pairs of poles
60 x 50
zzz -
18
= 166.7 r.p.m.
Synchronous speed for 16 pairs of poles
60 x 50
16 = 187.5 r.p.m.
As the head variation from the rated head is
mOre than 10% lower synchronous speed i.e. a
synchronous speed of 166.7 r.p.m. is being
adopted.
:. Corrected specific speed
166.7 4 106:358
= ____.~. ._ cI
1005/4
194
A-3 TURBINE SETTING
Hs < Hb- aH-HH,
Here
Hb = 10 m,
H, = O-4 m
H = 105 m,.and
G m from Fig. 3 corresponding a specific
speed of 194 = 0.12
:. Hs < IO - 0.12 x 105 - 0.4 m
< - 3-Om.
With a further margin of 0.5 met% the centre
line of the distributor should be set 3-O+ 0.5
= 3.5 metres below minimum tailrace level as
defined in 3.2.
A-4 SIZE OF RUNNER
Discharge diameter, & =- 6o ( 2 gH)“‘6~& as in
7xI1
IS 12800 ( Part 2 ) : 1989.
where
H = 105 m,
n = 166.7, and
Ku = from Fig. 6 corresponding to a specific
speed of 194 = 0.71
:*
o3 60 ( 2 x 9.81 x 105 )O*tx 0.71
_-.-
~-2.14 x 166.7
= 3.69 m.
Say 3.7 metres.
A-5 DIMENSIONS OF SPIRAL CASE
As the gross head above the turbine is more
than 30 metres, metallic spiral casing should be
used. The main dimensions of the spiral casin
as determined in accordance with Fig. 8, f
and 10 work out to be as shown below:
A = I.1 x 3.7 = 4.07 m
B = 1.39 x 3.7 = 5.14 m
c= I.57 x 3.7 = 5.81 m
D = 1.74 x 3.7 = 6.44 m
E = 1.29 x 3.7 = 4.77 m
F = 1.65 x 3.7 = 6.11 m
G = I.38 x 3.7 7 5.11 m
H 6 1.2 x 3.7 = 4.44 m
I- O-235 x 3.7 = 0.87 m
L = 0.98 x 3.7 - 3.63 m
M = O-61 x 3.7 = 2.26 m
A-6 SIZE OF DRAFT-TUBE
The various dimensions of the draft-tube shown
in Fig. 12 as determined in accordance with
IS 5496 : 1969 should be as below:
Height of draft-tube at exit end
h = 0.94 0s to 1.32 &.
As the specific speed of the turbine is on the
lower side, ‘h’ will be on the higher side.
Taking it _ 1.25 J!&,h = 1.25 x 3.7 =
4.65 m
Depth of draft tube ‘Iit’ for Francis Turbine
= 2.5 to 3.0 Dy.
Taking H1 5 2.75 D3, NL = 10.2 m.
Length of draft-tube Z_= 4 to 5 &.
Taking L = 4.5 Dj, L r 4.5 x 3.7 =
16.70 m.
Cleat width ‘B’ of the druft-tube at exit end
= 2.6 to 3.3 Da.
Since the clear width of the draft-tube is cxces-
sive, a pier til‘ 1.5 metros vidth shuulti be
introduced in the cenlrc of the drnft-tube. The
total width of the ciraft-tub: n.iII. t!l~.l.,, be
12.5 m.
Since, power 111
kW :: 9.R x Q x i/ :c .,.,
14

20. IS 12800 ( Part 1 ) : 1993
where
Q = discharge in cumecs,
W
A-7.5 Core length of stator ‘Lc) = K. Dg’ I,
H= rated head in metres, and
r) = efficiency of machine.
Assuming efficiency of machine to be 0.9,
e
100 x 1 000
_._ __---_ = 113.5 cumecs
= -!GG x 100 x 0.9
where
W = 11000 kVA,
K,, = 6.6 ( from Fig. 16 ),
Dg = 8.1 metre
II = 166.7 r.p.m.
:. Velocity at the exit end of draft-tube,
V, = -a-&$-ic = 2.219 m/set.
L,
11 000
:. =
6.6 x (8.1)’ x 166.7 = 1’54m
Say 1.5 m
IO accordance with 2.5 of IS 5496 : 1969, mini-
mum submergence at the outlet end of draft-
A-7.6 Length of stator frame ‘~~9
tube should be greater than 0.3 metre, or c L, + 1.5 to 1.6 m
Vc”
___ i e i_?f??.F -_ O-251 nl
E 1.5 + 1.5 = 3.0 m
2g ’ ’ 2 x 9.81 A-7.7 Axial hydraulic thrust PH = KD$ Hmax
Say 0.3 m. in tonnes,
Keeping bed slope 1 vertical to 10 horizontal at where
the bottom of the draft-tube, the exit end of
draft-tube will be 1.67 metres above the bottom
K = 0.19 from Fig. 17,
of draft-tube. Ds = 3.7 m, and
:. Top of exit end of draft-tube will be
H max - 105 m.
1.67 + d1.65= 6.32 m above the bottom :. PlI = 0.19 x 3.7 x 105 = 273 tonnes.
of the draft-tube.
Since height of draft-tube below centre line of
A-7.8 Weight of generator rotor Wn - 225 x
1.5 tonnes ( from Fig. 18 ) - 338 tonnes
guide apiaratus is 10.2 metres and the centre
line of guide apparatus itself is 3.5 metres below
minimum tail water level, the top of the exit
end of draft-tube will be ( 3.5 + 10.2 - 6.32 )
= 7.38 metres below minimum tail water level,
which is in order.
A-7.9 Weight of turbine runner = 23 tonnes
( from Fig. 19 ).
A-7.10 Height of load bearing bracket ‘hi’ =
Total weight of rotating parts + axial thrust
= 338 + 23 f 273 w 634 tonnes.
Let there be 6 arms in the bearing bracket,
634
A-7 GENERATOR PARAMETERS
A-7.1 Air Gap Diameter ‘DR’
Total number of pair of poles = 18
Rated kVA of generator = 100 000/o-9
= 111 000.
From Fig. 15, Da = 8-i m
A-7.2 Outer core diameter D,
G I); ( 1 + -5 ) metres
_ 8.1 1 1.
’
_.XP
2x18) = 8,807 m
Say 8.8 metres.
A-7.3 Stator frame diameter Df
= D, + 1.2 metres
= 8.8 t_ l-2 = IO.0 m.
A-7.4 Inner diameter of generator barrel Db
- D, + I.6 to 2.0 m
_: IO.0 + l-8 = 11.8 m.
Load on each arm - 6 = 105.7
Say 106 tonnes.
Height of load bearing bracket ‘hj = K J-i%
for suspended type construction, and
= JKZ, for umbrella type construction
where
K- 0.85 ( see 5.7.1 ).
:. hj = 0.85 dlO = 2.64 for suspended type
construction, and
-_.
= 0.85 4 8.1 == 2.42 for umbrella type
construction.
A-8 OVERALL DIMENSIONS OF POWER
STATION
A-8.1 From Fig. 21 drawn in accordance
with 6.2.1, the extremities of scroll case/draft
tube/generator in longitudinal direction are at
15

21. IS 12800( Part 1 ) : 1993
7-l 15on spiral inlet side and 6.5 m on opposite
side of the transverse centre line of the machine.
Adding l-5 to 2 metres to these dimensions, the
size of the unit bay in longitudinal direction or
unit spacing work out to be 17 metres.
Length of erection bay = 0.7 to I.5 times the
unit bay size = 1 x 17 = 17 m.
Space required for the E.O.T. crane to handle
the last unit will depend upon the number and
size of the crane. For preliminary purpose
assuming it to be 3 to 5 metres ( 4 metres in the
present case).
Total length of power station = 4 x 17 + 17
+ 4 = 89 m.
From Fig. 21 and 22 and 6.3, the distance of the
inner face of downstream columns from the
longitudinal centre line of machine works out
to be 6.5 + ( 1.5 to 2.0, Say 2.0 ) = 8.5 m.
Distance of the inner face of upstream columns
from the longitudinal centre line of machine
= 6.5 ( extremity of draft-tube/scroll-case/
generator barrel ) + 4.00 ( For accommodating
control valve; the same space can also be used
for approaching draft-tube ) = 10.5 m.
A-8.2 Total height of machine ( see Fig. 20 )
= HI + H,
From the size of draft-tube as already calcula-
ted in A-6, HI - 10.2 m.
Hz = Lr + hi + K ( see 6.4.2 ).
As already calculated, Lr = 3.0 metres and
hj = 2.69 ( For suspended type machine ).
K = 5.5 to 7.0, Say 6.0 m.
:. H, = 3.0 + 2.69 + 6 :-= 11.69 m.
:. Total height of machine IO.2 -i- 1I.69 -
21.89 m.
A-8.3 Total height of machine hall will depend
upon type of foundation, height of E.O.T.
crane, size of assemblies, type of roof and can
be determined accordingly.
All dimensions in millimetrrs.
FIG. 21 PLAN SHOWING MAIN DIMENSIONSOF UNIT BAY
16

22. IS 12800 ( Part 1 ) : 1993
--lo75o~-+.-d35oo
--13500--y SPIRALCASING
n
<ENSTOCK
’ Y
All dimensions in millimetres.
FIG. 22 CROSS SECTIONOF POWER
HOUSE
17

23. _~~~~ ___..
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