SIST EN 60041:2001

SLOVENSKI STANDARD
01-marec-2001
1DGRPHãþD
SIST IEC 60041:1999
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Field acceptance tests to determine the hydraulic performance of hydraulic turbines,
storage pumps and pump-turbines
Abnahmeversuche zur Bestimmung der hydraulischen Eigenschaften von
Wasserturbinen, Speicherpumpen und Pumpturbinen
Essais de réception sur place des turbines hydrauliques, pompes d'accumulation et
pompes-turbines, en vue de la détermination de leurs performances hydrauliques
Ta slovenski standard je istoveten z: EN 60041:1994
ICS:
27.140 Vodna energija Hydraulic energy engineering
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL IEC
STANDARD
Third edition
1991-11
Field acceptance tests to determine the
hydraulic performance of hydraulic turbines,
storage pumps and pump-turbines
 IEC 1991 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical,
including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
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Commission Electrotechnique Internationale
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue

41 © I E C - 3 -
CONTENTS
Page
FOREWORD 9
PREFACE 9
SECTION ONE - GENERAL RULES
Clause
1. Scope and object 13
1.1 Scope 13
1.2 Object 13
1.3 Types of machines 13
1.4 Reference to IEC and ISO standards 15
1.5 Excluded topics 15
2. Terms, definitions, symbols and units 15
2.1 General 15
2.2 Units 15
2.3 List of terms, definitions, symbols and units 15
3. Nature and extent of hydraulic performance guarantees 51
3.1 General 51
3.2 Main guarantees 51
3.3 Other guarantees 55
4. Organisation of test 59
4.1 Adequate provision for the test 59
4.2 Authority for test 59
4.3 Personnel 59
4.4 Preparation for test 59
4.5 Agreement on test procedure 61
4.6 Instruments 63
4.7 Observations 63
4.8 Inspection after test 65
4.9 Final report 67
SECTION Two- EXECUTION OF TEST FOR THE DETERMINATION
OF THE STEADY STATE PERFORMANCE OF THE MACH INE
5. Test conditions and procedure 71
5.1 General test procedure 71
5.2 Test conditions to be fulfilled
6. Computation and analysis of results 81
6.1 Computation of test results
6.2 Uncertainties in measurements and presentation of results 87
6.3 Comparison with guarantees 93
SECTION TI IREE - EXECUTION OF TEST FOR THE DETERMINATION
OF TRIE TRANSIENT CHARACTERISTIC OF THE MACHINE
7. Test conditions and procedure
7.1 Test conditions
trumentation 7.2 Test procedure and ins

41© IEC -5 -
Page
Clause
8. Computation and analysis of results
8.1 Conversion of results
8.2 Comparison with guarantees
SECTION FOUR - METHODS OF MEASUREMENT
9. Introduction 115
9.1 Efficiency
9.2 Hydraulic power
9.3 Mechanical power
10. Discharge
10.1 General
10.2 Current-meter method
10.3 Pitot tubes
10.4 Pressure-time method 147
10.5 Tracer methods 163
10.6 Weirs 167
10.7 Standardized differential pressure devices 179
10.8 Volumetric gauging method 181
11. 187
Specific hydraulic energy of the machine
11.1 General 187
11.2 Determination of the specific hydraulic energy 189
11.3 Determination of the net positive suction specific energy
11.4 Pressure measurements
11.5 Free water level measurements
11.6 Uncertainty of measurements 251
12. Power 253
12.1 Indirect method of power measurement 253
12.2 Direct method of power measurement 283
12.3 Bearing losses
13. Rotational speed
13.1 General
13.2 Speed measurements in the case of direct measurement of power
13.3 Speed measurements in the case of indirect measurement of power
13.4 Uncertainty of measurement
14. Thermodynamic method for measuring efficiency 293
14.1 General
14.2 Efficiency and specific mechanical energy
14.3 Procedure for measurement of specific mechanical energy
14.4 Apparatus
14.5 Test conditions to be fulfilled
14.6 Corrective terms
14.7 Uncertainty of measurement

41 © IEC 7
Page
Clause
15. Index tests
15.1 General 321
15.2 Relative discharge measurement
15.3 Measurement of other quantities 331
15.4 Computation of results 331
15.5 Uncertainty of measurement
APPEr\TDIX A — Systematic uncertainties in performance measurements at steady state conditions
APPENDIX B — Rejection of outliers
APPENDIX C — Analysis of the random uncertainties for a test at constant operating conditions
D — Analysis of the random uncertainties for a test over a range of operating conditions . 363
APPENDIX
APPENDIX E — Physical data
APPENDIX F — Derivation of the equation for the specific hydraulic energy of a machine
APPENDIX G — Measurement of electric power — Determination of the correction for a single-phase
measuring system
APPENDIX H — Thermodynamic method — Examples for a balance of power and computation of the
specific mechanical energy
APPENDIX J — Acoustic method of discharge measurement

41 © IEC — 9 —
INTERNATIONAL ELECTROTECHNICAL COMMISSION
FIELD ACCEPTANCE TESTS TO DETERMINE
THE HYDRAULIC PERFORMANCE OF HYDRAULIC TURBINES,
STORAGE PUMPS AND PUMP-TURBINES
FOREWORD
The formal decisions or agreements of the IEC on technical matters, prepared by Technical Committees on which all the National
1)
rnational consensus of opinion on the
Committees having a special interest therein are represented, express, as nearly as possible, an inte
subjects dealt with.
and they arc accepted by the National Committees in that sense.
2) They have the form of recommendations for international use
In order to promote international unification, the I E C expresses the wish that all National Committees should adopt the text of the I EC
3)
recommendation for their national rules in so far as national conditions will permit. Any divergence between the I E C recommendation
and the corresponding national rules should, as far as possible, be clearly indicated in the latter.
PREFACE
This International Standard has been prepared by IEC Technical Committee No. 4: Hydraulic turbines.
It replaces the second edition of IEC 41, the first edition of IEC 198 and the first edition of IEC 607.
The text of this standard is based on the following documents:
Report on Voting
Six Months' Rule
4 (CO) 52
4 (CO) 48
Full information on the voting for the approval of this standard can be found in the Voting Report indicated in
the above table.
The following IEC publications are quoted in this standard:
Publications Nos. 34-2 (1972): Rotating electrical machines. Pa rt 2: Methods for determining losses and efficiency of rotating
electrical machinery from tests (excluding machines for traction vehicles).
34-2A (1974): First supplement: Measurement of losses by the calorimetric method.
185 (1987): Current transformers.
186 (1987): Voltage transformers.
Amendment No.1 (1988).
(1965): International code for model acceptance tests of hydraulic turbines.
Amendment No.1 (1977).
193A (1972): First supplement.
(1970): International code for testing of speed governing systems for hydraulic turbines.
(1976): International code for model acceptance tests of storage pumps.
(1976): Guide for commissioning, operation and maintenance of hydraulic turbines.
(1978): Cavitation pitting evaluation in hydraulic turbines, storage pumps and pump-turbines.
ce of storage pumps and of pump-turbines
(1985): Guide for commissioning, operation and mainten an
operating as pumps.
41© IEC - 11 —
ISO standards quoted:
Publications Nos. 31-3 (1978): Quantities and units of mechanics. Amendment 01-1985.
748 (1979): Liquid flow measurements in open channels – Velocity-area methods.
1438-1 (1980): Water flow measurement in open channels using weirs and Ventu ri flumes-Part 1: Thin-plate
weirs.
2186 (1973): Fluid flow in closed conduits – Connections for pressure signal tr ansmissions between primary
d
an secondary elements.
2533 (1975): Standard Atmosphere. Addendum 01-1985.
2537 (1988): Liquid flow measurement in open channels –Rotating element current-meters.
2975: Measurement of water flow in closed conduits – Tracer methods.
2975-1 (1974): Part I: General.
2975-2 (1975): Part II: Constant rate injection method using non-radioactive tracers.
III: Constant rate injection method using radioactive tracers.
2975-3 (1976): Pa rt
2975-6 (1977): Pa rt VI: Transit time method using non-radioactive tracers.
2975-7 (1977): Part VII: Transit time method using radioactive tracers.
3354 (1988): Measurement of clean water flow in closed conduits – Velocity area method using current-meters
in full conduits and under regular flow condi tions.
3455 (1976): Liquid flow measurement in open channels – Calibration of rotating-element current-meters in
straight open tanks.
3966 (1977): Measurement of fluid flow in closed conduits – Velocity area method using Pitot static tubes.
4373 (1979): Measurement of liquid flow in open channels – Water level measuring devices.
(1980): Measurement of fluid flow by means of orifice plates, nozzles and Venturi tubes inserted in
circular cross-section conduits running full.
5168 (1978): Measurement of fluid flow–Estimation of uncertainty of a flow-rate measurement.
7066: Assessment of uncertainty in the calibration and use of flow measurement devices.
7066-1 (1989): Part 1: Linear calibration relationships.
7066-2 (1988): Part 2: Non-linear calibration relationships.

—13
41©IEC
FIELD ACCEPTANCE TESTS TO DETERMINE
THE HYDRAULIC PERFORMANCE OF HYDRAULIC TURBINES,
STORAGE PUMPS AND PUMP-TURBINES
SECTION ONE – GENERAL RULES
Scope and object
1 Scope
1.1 This International Standard covers the arrangements for tests at the site to determine the extent to which
the main contract guarantees (see 3.2) have been satisfied. It contains the rules governing their conduct and
ase of the tests is disputed. It deals with methods of computation
prescribes measures to be taken if any ph
well the extent, content and style of the final repo rt.
of the results as as
1.2 Model tests, when used for acceptance purposes, are dealt with in IEC 193 with Amendment No. 1, first
supplement 193 A, and in IEC 497.
1.3 Tests of speed governing systems are dealt with in IEC 308.
Object
The purpose of this standard for field acceptance tests of hydraulic turbines, storage pumps or pump-
turbines, also called the machine, is:
– to define the terms and quantities which are used;
to specify methods of testing and ways of measuring the quantities involved in order to ascertain the
–
hydraulic performance of the machine;
to determine if the contract guarantees which fall within the scope of this standard have been fulfilled.
–
The decision to perform field acceptance tests including the definition of their scope is the subject of an
lier of the machine. For this, it has to be examined in each
agreement between the purchaser and the supp
case, whether the measuring conditions recommended in this standard can be realized. The influence on
the measuring uncertainties, due to hydraulic and civil conditions has to be taken into account.
If the actual conditions for field acceptance tests do not allow compliance with the guarantees to be
proved, it is recommended that acceptance tests be performed on models (see 1.1.2).
Types of machines
In general, this standard applies to any size and type of impulse or reaction turbine, storage pump
or pump-turbine. In particular, it applies to machines coupled to electric generators, motors or motor-
generators.
a turbine and the
as
For the purpose of this standard the term turbine includes a pump-turbine functioning
term pump includes a pump-turbine functioning as a pump. The term generator includes a motor-generator
functioning as a generator and the term motor includes a motor-generator functioning as a motor.

— 15 —
41 © IEC
1.4 Reference to IEC and ISO Standards
IEC and ISO Standards referred to in this standard are listed in the preface. If a contradiction is found
between this standard and another IEC or ISO standard, this standard shall prevail.
1.5 Excluded topics
1.5.1 This standard excludes all matters of a purely commercial interest except those inextricably bound up with
the conduct of the tests.
1.5.2 This standard is concerned neither with the structural details of the machines nor with the mechanical
properties of their components.
2. Terms, definitions, symbols and units
2.1 General
The common terms, definitions, symbols and units used throughout the standard arc listed in this clause.
Specialised terms arc explained where they appear.
The following terms arc given in 5.1.2 and Figure 11:
comprises the readings and/or recordings sufficient to calculate the performance of the machine
1) A run
at one operating condition.
is established by one or more consecutive runs at the same operating conditions and unchanged
2) A point
settings.
A test comprises a collection of data and results adequate to establish the performance of the machine
3)
over the specified range of operating conditions.
The clarification of any contested term, definition or unit of measure shall be agreed to in writing by the
contracting parties, in advance of the test.
2.2 Units
The International System of Units (SI) has been used throughout this standard*.
2). The basic
All terms are given in SI base units or derived coherent units (e.g. N instead of kg  m  s-
equations arc valid using these units. This has to be taken into account, if other than coherent SI Units are
5 Pa)
for certain data (e.g. kilowatt or megawatt instead of watt for power, kilopascal or bar (= 10
used.
instead of s- 1 for rotational speed, etc.). Temperatures may be given
instead of pascal for pressure, min -1
in degrees Celsius because thermodynamic (absolute) temperatures (in kelvins) are rarely required.
Any other system of units may be used but only if agreed to in writing by the contracting parties.
2.3 List of terms, definitions, symbols and units
2.3.1 Subscripts and symbols
The terms high pressure and low pressure define the two sides of the machine irrespective of the flow
direction and therefore are independent of the mode of operation of the machine.
* See ISO 31-3.
41 © IEC —
17 —
Sub-clause Term Definition Subscript
symbol
2.3.1.1 High pressure The high pressure section of the machine 1
reference to which the performance guarantees refer
section (see Figure 1)
2.3.1.2 Low pressure The low pressure section of the machine 2
reference
to which the performance
section guarantees refer (see Figure 1)
2.3.1.3 High pressure Whenever possible these sections 1', 1", .
measuring should coincide with section 1:
sections otherwise the measured values shall
be adjusted to section 1
(see 11.2.1)
2.3.1.4 Low pressure Whenever possible these sections 2', 2", .
measuring should coincide with section 2:
sections otherwise the measured values shall
be adjusted to section 2
(see 11.2.1)
2.3.1.5 Specified Subscript denoting values of sp
quantities such as speed, discharge
etc. for which other quantities are guaranteed
2.3.1.6 Maximum Subscripts denoting maximum max
Minimum or minimum values of any term min
2.3.1.7 Limits Contractually defined values:
— not to be exceeded
ffffK
O
—to be reached F
2.3.1.8 Ambient Subscript referring to surrounding atmospheric conditions amb
Turbine
Pump
IEC 362/91
Figure 1— Schematic representation of a hydraulic machine

— 19 —
41 © IEC
2.3.2 Geometric terms
Symbol Unit
Sub-clause Tenn Definition
2.3.2.1 Net cross sectional area normal to A m2
Area
general flow direction
2.3.2.2 Guide vane Average vane angle measured from a degree
opening closed position* or average
shortest distance between a m
adjacent guide vanes (at a defined
position, if necessary)
(see Figure 2)
2.3.2.3 Needle Average needle stroke measured s m
opening from closed position'
(impulse
turbine)
degree
2.3.2.4 Runner Average runner blade angle measured 0
blade from a given position*
opening
2.3.2.5 Elevation of a point in the system z to
Level
above the reference datum
(usually mean sea level)
2.3.2.6 Difference of elevation between m
Difference Z
any two points in the system
of levels
lEC 363/91
Figure 2 — Guide vane opening (from closed position)
* Under normal working oil pressure.

41 © IEC — 21 —
2.3.3 Physical quantities and properties
Sub-clause Tenn Definition Symbol Unit
s-2
2.3.3.1 as a function g m •
Acceleration Local value of g
duc
to of altitude and latitude of
gravity
the place of testing
(see Appendix E, Table EI)
K
2.3.3.2 Temperature Thermodynamic temperature; O
Celsius temperature r9 = O — 273,15 r9 °C
m-3
2.3.3.3 Density Mass per unit volume kg •
m-3
a) Values for water are given in kg •
B w
Appendix E, Table EII (g is commonly
used instead of w)
e
Values for air are given in 0, kg • m-3
b)
Appendix E, Table EIII. Usually
the value of air density at
the reference level of the
machine (see 2.3.7.10)
is used
kg • m-3
c) Values for mercury are given in p jig
Appendix E, Table EIV
2.3.3.4 Specific Volume per unit mass. Used only for 11g m3 • kg-1
volume water in this standard
m3 - kg-1
2.3.3.5 Isothermal Factor characterizing a thermodynamic
a
factor property. Values for water are given
in Appendix E, Table EV
J
2.3.3.6 Specific The rate of change of enthalpy per cR .kg- 1 • °C-1
heat unit mass with change in temperature or
J
capacity at constant pressure. Values for water • kg-1 • K-1
arc given in Appendix E, Table EVI
l'a
2.3.3.7 Vapour For purposes of this standard the p ,
v
pressure absolute partial pressure of the
(absolute) vapour in the gas mixture over the
liquid surface is the saturation
vapour pressure corresponding to the
temperature. Values for distilled
water arc given in Appendix E, Table EVII
A quantity characterising theµPa • s
2.3.3.8 Dynamic
mechanical behaviour of a fluid
viscosity
(sec ISO 31-3)
Ratio of the dynamic viscosity to the v m2 • s-1
2.3.3.9 Kinematic
viscosity density: v = L
e
41 © IEC — 23 —
2.3.4 Discharge, velocity and speed terms
Sub-clause Term Definition Symbol Unit
2.3.4.1 Discharge Volume of water per unit time flowing through any section Q m3 • s-1
(volume flow rate) in the system
2.3.4.2 Mass flow rate Mass of water flowing through any section of the system kg • s -1
(eQ)
per unit time. Both e and Q must be determined at the
same section and at the conditions existing in that section
Note. – The mass flow rate is constant between two
sections if no water is added or removed.
2.3.4.3 Measured
Volume of water per unit time flowing through any Q1, or Q 2, m3 • s-1
discharge
measuring section, for example 1' (see 2.3.1.3 and
2.3.1.4)
2.3.4.4 Discharge at Volume of water per unit time flowing through the or Q., m3 • s-1
Q1
reference section reference section 1 or 2
s-1
2.3.4.5 Corrected Volume of water per unit time flowing through a reference Q1 or Q2c m3 •
c
discharge at section referred to the ambient pressure
reference section (see 2.3.5.2) e.g.
Q1c — (eQ)llepamb
(sec 3.2.3) where gip. is the density at ambient
mb
pressure and the water temperature at the reference
section
2.3.4.6 No-load turbine Turbine discharge at no-load, at specified speed and Qo m3 • s-1
discharge specified specific hydraulic energy and generator not
excited
2.3.4.7 Index discharge Discharge given by relative (uncalibrated) flow m3 • s-1
Q;
measurement (see Clause 15) -
m . s-1
2.3.4.8 Mean velocity Discharge divided by the area v
A
2.3.4.9 Rotational speed Number of revolutions per unit time n 3-1
2.3.4.10 No load turbine The steady state turbine speed at no load with governor no s-1
speed connected and generator not excited
s-1
2.3.4.11 Initial speed The steady state turbine speed just before a ch ange in n 1
operating conditions is initiated (see Figure 3)
s-1
2.3.4.12 Final speed The steady state turbine speed after all transient waves n r
have been dissipated (see Figure 3)
specified load
2.3.4.13 Momentary The highest speed attained during a sudden n s-1
overspeed of a rejection from a specified governor setting
turbine (sec Figure 3)
s-1
Maximum The momentary overspeed attained under the most
2.3.4.14
m max
momentary unfavourable transient conditions (in some cases
overspeed of a the maximum momentary overspeed can exceed the
turbine maximum steady state runaway speed)
s-1
2.3.4.15 Maximum steady the speed for that position of needles or guide vanes
n R max
state runaway and/or runner/impeller blades which gives the highest
speed value after all transient waves have been dissipated with
electrical machine disconnected from load or network and
not excited, under the maximum specific hydraulic energy
(head). The runaway speed particularly of high specific
speed machines may be influenced by cavitation and thus
depends on the available LAPSE (see 2.3.6.9)

41©IEC —25 —
i
ni
nt
1EC 364/91
Figure 3 — Variation of turbine speed during a sudden load rejection
2.3.5 Pressure terms
Sub-Clause Tenn Definition Symbol Unit
Pa
2.3.5.1 Absolute The static pressure of a fluid measurement with
gabs
pressure reference to a perfect vacuum
2.3.5.2 Ambient pressure The absolute pressure of the ambient air Pa
Pamb
2.3.5.3 Gauge pressure The difference between the absolute presssure of a p Pa
fluid and the ambient pressure at the place and time
of measurement:
P — paba — Pamb
2.3.5.4 Initial pressure The steady state gauge pressure which occurs at a p; Pa
specified point of the system just before a change in
operating conditions is initiated (see Figure 4)
2.3.5.5 Final pressure The steady state gauge pressure which occurs at a p r Pa
specified point of the system after all transient waves
have been dissipated (see Figure 4)
Pa
2.3.5.6 Momentary The highest/lowest gauge pressure which occurs at a
pm
p; Pa
pressure specified point of the system under specified transient
conditions (see Figure 4)
Pa
2.3.5.7 Maximum/ The momentary pressure under the most unfavourable
P, max
– Pa
minimum transient condition
p
m min
momentary
pressure
41 © IEC —
27 —
a)
Pf
b)
Pi
IEC 36519!
Figure 4a — Variation of pressure at the turbine high pressure reference section
a) when a specified load is suddenly rejected
b) when a specified load is
suddenly accepted
Pf
IEC 366191
Figure 4b — Variation of pressure at the pump high p ssure
re
reference section during a power failure

41© IEC —29 —
2.3.6 Specific energy terms
In the International System of Units the mass (kg) is one of the base quantities. The energy per unit
mass, known as specific energy, is used in this standard as a primary term instead of the energy per local
unit weight which is called head and was exclusively used in the former IEC 41 and 198.
The latter term (head) has the disadvantage that the weight depends on the acceleration due to gravity
which changes mainly with latitude but also with altitude. Nevertheless, the term head will still remain
g,
in use because it is very common. Therefore both related energy terms are listed, the specific energy terms
g,
in this sub-clause and the head terms in 2.3.7. They differ only by the factor which is the local value of
acceleration due to gravity.
The symbol for specific energy at any section of flow is the small letter e; the symbol for the difference
h and
of specific energies between any two sections is the capital letter E. The same applies to H.
Term Definition Symbol Unit
Sub-clause
2.3.6.1 Specific energy The energy per unit mass of water at any section e J - kg-1
(m2 . s-2)
Specific energy of water available between the J • kg-1
2.3.6.2 Specific E
high and low pressure reference sections of the
hydraulic energy
machine, taking into account the influence of the
of machine
compressibility
= v2 v2
E Pabst — Pabst 1 2 +9
+ (z1 — z2)
Q 2
22 +.
with T. 1 2 and g . •
Note. – The value of gravity acceleration at the
reference level of the machine (see 2.3.7.10) may be
assumed as T.
and e2 can be calculated from
The values of
el
respectively, taking into account 491
and
pabsl pabs2
for both values, given the negligible influence
or 492
of the difference of the temperature on e
J • kg- 1
2.3.6.3 Specific Mechanical power transmitted through the coupling Em
d shaft (see Clause 14)
mechanical of the runner(s)/impeller(s) an
energy at divided by mass flow rate:
runner(s)/ p
Em = " (for Pm , see 2.3.8.4)
impeller(s
(eQ)1
J • kg- 1
Specific Specific hydraulic energy available between head Eg
2.3.6.4
ant
hydraulic energy water level and tailwater level of the pl
of the pl ant (see Figure 6)
It is given by:
pa h
,
E = 3 — Pahs4 v23 — v4
+ +(z3 —
z4)
B 2
e
e.2^4 93294
with -J. and
9_
The water density at ambient pressure may be
assumed as
e-
Figures 5a, 5b (reaction machines) and 5c (impulse turbines) illustrate some common cases of application of the basic formula for
the specific hydraulic energy. The applicable simplified formula is given under each figure. Measurement methods for the evaluation
of the specific hydraulic energy of the machine arc described in detail in Clause 11.
 See Appendix F.
31 —
41 © IEC —
Symbol Unit
Sub-clause Term Definition
Pump specific energy at specified speed and specified E0 J • kg-1
2.3.6.5 Zero-discharge
runner/impeller blade settings with high
(shut-off) guide vane and
specific hydraulic pressure side shut-off
energy of the
pump
J • kg-1
Specific The specific hydraulic energy dissipated between any two EL
2.3.6.6
hydraulic energy sections
loss
ELs J • kg-1
2.3.6.7 Suction specific The specific hydraulic energy dissipated between the
d the low pressure reference section of
hydraulic energy tailwater level an
loss the machine (see figure 41)
E J • kg-1
2.3.6.8 Suction specific Specific potential energy corresponding to the difference
potential energy between the reference level of the machine (see 2.3.7.10)
of the machine and the piezometric level at section 2:
Zs (see Figure 7)
,.
Es = 92 (z — = 2
z 2, )
NPSE J • kg-1
2.3.6.9 Net positive Absolute specific energy at section 2 minus the specific
referred to the
suction specific energy due to vapour pressu re per',
reference level of the machine according to Figure 7
energy
L2
Paba2 — Pva +
= NPSE
92(z r — z2) **
e2 2
2.3.7 Height and head terms
Unit
Symbol
Sub-clause Term Definition
d m
Geodetic height Difference in elevation between headwater level an Z g
2.3.7.1
of plant"* tailwater level of plant (see Figure 6)
h m
2.3.7.2 IIcad Energy per unit weight of water at any section
h = e/g
For definition of e, see 2.3.6.1
H m
Turbine or pump H = En
233.3
head
For definition of E, see 2.3.6.2
H
2.3.7.4 Plant head*** H g = Eg /g m
see 2.3.6.4
For definition of Eg ,
He m
Zero-discharge Ho = Eo
2.3.7.5 /79
(shut-off) head of
For definition of E0 , see 2.3.6.5
pump
HL
head loss HL = m
2.3.7.6 EL/9
For definition of EL , see 2.3.6.6
Appendix E, Table EVII.
 See 2.3.3.7 and
" For definition of cavitation factor a, sec IEC 193A and 497.
d plant head.
an
 Figure 6 shows the relationship between geodetic height of plant

33 —
41 © IEC —
Symbol Unit
Sub-clause Term Definition
m
IILs = TE 's "Ls
2.3.7.7 Suction head loss
see 2.3.6.7
For definition of ELs ,
Es
m
Suction height Zs = — (see Figure 7) Zs
2.3.7.8
For definition of Es , see 2.3.6.8
NPSE
in
NPSH
2.3.7.9 Net positive NPSH =
suction head 92
see 2.3.6.9
For definition of NPSE,
m
Elevation of the point of the machine taken as z r
2.3.7.10 Reference level
reference for the setting of the machine as defined in
of the machine
Figure 8
1EC 367/91
Figure 5a – Low-head machines – Determination of specific hydraulic energy of machine

41 © IEC
— 35 —
Water column manometers arc applied at point 1 and 2.
_ ^
/
vl
(Pabst ^ab^s- + (
v2
+
E_ JII _
z
J( l — z2)
The compressibility of water is neglected because the difference of pressure between 1 and 2 is small
therefore:
P1=P2= P
Hence:
l, — z
=
Pabs 1 P . J(z 1) + pambl,
z
=
Pabs 2 P - 9(z2, — 2) + pamb2,
— z,,)
Pamb 1 pamb 2 — ea . 3(z1,
, — , —
and therefore the simplified formula is:
^ (vj—
(v^—v;)—^ (1 Oa v')
E zl 2 r Z 1— ^ +
,—z , 1— + J Pa J( ) t
2 2
The water density at ambient pressure may be assumed as 13.

Vertical shaft unit
Horizontal shaft unit
EEC 368/91
Figure 5b — Medium and high-head machines — Determination of specific hydraulic energy of machine
and 2.
Pressure gauges manometers are applied at points 1
z
V:3)
= (Pabs l ^ i/abs2  E = .5H + (vl

-+ J(
z 1 — z2)
H,
Z is small compared to
The difference in ambient pressure between 1' and 2' is neglected because
therefore:
pamb2 i — Pamb
Pambl' =
Since both and Z2 are small compared to H, it may be assumed that:
Z 1
Pl 2
Z1  = Z and Z 2
=
Z2
e
41 © IEC — 37 —
hence:
pamb where p 1, is the gauge pressure measured at 1'
P1
T abs, = , + Z1  el ' 9 +
e2 .-Ù- where p 2, is the gauge pressure measured at 2'
2'9 +
pab, = P2' + Z2  pamb
and therefore the simplified formula is:
(Pl i — P2') (y? — v?) _ ^P1^ — P2^) lvï — v3)
E = – I ^ (z 1 2 Z + , – z ,) } 2 – 1 g
–
!EC 369/91
Figure 5c – Pelton turbines with vertical axis – Determination of specific hydraulic energy of machine
Case of non-pressurised housing.
It is conventionally assumed that the low pressure reference section corresponds to the plane at elevation
z, and that the pressure inside the housing is equal to the ambient pressure in the case of non-pressurised
housing.
(Albs ^ — Pabs^ ) vi) lvl — (
E
+ +9
l-1 -2)
-
II,
The difference in ambient pressure between 1' and 2 is neglected because Z is small compared to
therefore:
Pambl i = Pamb2 = Pamb
For the same reason it is assumed that:
P 1
Z  =Z
hence:
amb where pl, is the gauge pressure measured at 1'
P
Pabst = Pi, + Z  91 ' 9 +
Pabst = Pamb
41 © IEC — 39 —
As z 1 = z2 and assuming v 2 = 0, the simplified formula is:
E = =p'+^Z +vï
pl'-F^  (
z 1, '21+ ^
3 and 4 refer to the
water levels at the outer
boundaries of the plant
Z4
Reference datum
^ Z3—Z4
=
IEC 370/91
and head H of plant
Figure 6 - Hydroelectric plant - Determination of specific hydraulic energy E g g
through geodetic height of plant Zg
The general formula is:
(v3 —
pabs4 (pabs3 — )
vi)
=
E g 93-4' + 93-4(z3— z4)
Hg- +
2 e3-4
-
9s = -,
+Q4
^ Assuming
= 2
g Js-4
- z4);
a • •
Pabs3 — Pabs 4 - —e 9
assuming y3 = y4 = 0
water density at the ambient pressure, the formula becomes:
and n __ = =+ =
3 i
r n
[1— g • I1 —=1
=9•Z
Eg=J•(z
3 -z4)'
^ J E/
Aa L
is assumed equal to air density at the reference level of the machine.
where n a
Conversely:
+ turbine
where
Eg =E ^^
- pump
— 41 —
41 © IEC
Reference level of
the machine
(see 2.3.7.10)
IEC 371/91
NPSI-1
and net positive suction head,
NPSE,
Figure 7 — Net positive suction specific energy,
Water column manometer is applied at point 2.
v;
(Pabs — Pva)
NPSE = g2 NPSH = 2 + 2 r — z2^
g2  ( z
e2
With:
(2.2i — z2)
g + pamb2i
— e2 ' 2 
Pabs2
the simplified formula becomes:
Pva) v2
(pamb.,r —
(p Pva)va) + v;
amb2r —
, ) g2 S
_
g_ r — = +
z 2
'Z
°2
g2
is positive if the level 2' is lower than the reference level of the machine and vice versa.
where Zs
41 © IEC —
43 —
a) b) d)
Reference datum
6) f)
0 Reference datum
1FC
0° < a < 90°
a) Radial machines, such as Francis turbines, radial (centrifugal) pumps and pump-turbines; for multistage
machines: low pressuré stage.
b) Diagonal (mixed-flow, semi-axial) machines with fixed runner/impeller blades and with runner/impeller band.
c) Diagonal (mixed-flow, semi-axial) machines with fixed runner/impeller blades, without runner/impeller band.
d) Diagonal (mixed-flow, semi-axial) machines with adjustable runner/impeller blades).
e) Axial machines, such as propeller turbines, tubular turbines*', axial pumps and pump-turbines with fixed
runner/impeller blades.
,fl Axial machines, such as Kaplan turbines, tubular turbines**, axial pumps and pump-turbines with adjustable
runner/impeller blades.
g) Pelton turbines.
Figure 8 – Reference level of turbines, pumps and pump-turbines*
2.3.8 Power terms
Note.— All electrical power terms are defined in Clause 12.
Sub-clause Tent Definition Symbol Unit
2.3.8.1 lIydraulic power The hydraulic power available for producing power Ph W
(turbine) or imparted to the water (pump)
OPh
Ph = E(0Q)1 f
Hydraulic power Correction term to be evaluated after a relevant API, W
2.3.8.2
correction analysis according to contractual definitions and local
conditions*** (see 9.2.3)
* The reference level of the machine z r does not necessarily correspond to the point with maximum cavitation.
** The term "tubular turbines" includes bulb, pit, rim generator and S-type units.
q is taken from the system upstream of section 1 in a turbine and this water is contractually
*** Example: if a small discharge
chargeable to the hydraulic machine, the hydraulic power is: Ph =
E(2Q) 1 + E(eq)
41 © IEC — 45 —
Symbol Unit
Sub-clause Term Definition
The mechanical power delivered by the turbine shaft P W
2.3.8.3 Mechanical
power of the or to the pump shaft, assigning to the hydraulic
machine the mechanical losses of the relevant
machine (Power)
bearings (see Figure 9)
— For a turbine:
Pb+ Pc Pf
+ +Pd
P=Pa + Pe—
where:
Pa W
Pa is the generator power as measured at the
generator terminals
P b are the mechanical and electric losses in the Pb W
generator, including windage losses (see 12.1.2.1)
Q
are the thrust bearing losses due to generator. Pc W
Pc
In the case of a common thrust bearing, the bearing
losses shall be attributed to the turbine and generator
in proportion to the thrust of each on the bearing (see
12.1.2.2)
are the losses in all rotating elements external Pd W
Pd
to the turbine and to the generator, such as flywheel,
if any, gear, pump impeller in air, if any, etc. (see
12.1.2.3)
is the power supplied to any directly driven Pe W
Pe
auxiliary machine (see 12.1.2.4)
is the electric power supplied to the auxiliary Pf W
Pf
equipment of the turbine (e.g. for the governor) if the
contract specifies this to be chargeable to the turbine
— For a pump:
Pf
P=Pa—(Pb+Pc+Pd+Pe)+
where:
Pa is the power to the motor as measured at the Pa W
motor terminals
are the mechanical and electric losses in the Pb W
Pb
motor, including windage losses (see 12.1.2.1)
W
Pc are the thrust bearing losses due to the moto r. Pc
In the case of a common thrust bearing, the bearing
losses shall be attributed to the pump and motor in
ion to the thrust of each on the bearing (see
proport
12.1.2.2)
W
arc the losses in all rotating elements external Pd
Pd
d to the motor, such as flywheel, if any,
to the pump an
gear, starting turbine runner, turbine runner rotating
in air, etc. (see 12.1.2.3)
Pe is the power supplied to any directly driven Pe W
auxiliary machine (see 12.1.2.4)
P1 W
Pf is the electric power supplied to the auxiliary
equipment of the pump (e.g. for the governor) if the
contract specifies this to be chargeable to the pump

41 © IEC —
47 —
Sub-clause Term Definition Symbol Unit
2.3.8.4 Mechanical Mechanical power transmitted through the coupling Pm W
power of of the runner(s)/impeller(s) and the shaft (see
runner(s)/ demonstrative sketch Figure 9):
impeller(s)
— in the case of a turbine:
Pm=P+ Pf
PLm+
— in the case of a pump:
Pm =P — PLm — Pf
2.3.8.5 Mechanical Mechanical power dissipated -in guide bearings, thrust P
Lm W
power losses d
bearing an shaft seals of the hydraulic machine. See
also 2.3.8.3
(Pc)
2.3.8.6 Zero-discharge P0
Pump power at specified speed and at specified guide - W
(shut-off) power vane and impeller settings with high pressure side
of the pump shut-off
2.3.9 Efficiency terms
Sub-clause Term Definition Symbol Unit
2.3.9.1 I lydraulic — Fora turbine: n h
efficiency
_ Pm _ E m
nh
Ph E± Pp^E m
For a pump:
—
m
Ph
n
h = — _
Pm Em
P
2.3.9.2 Mechanical
— For a turbine: n m= n m
—
Pm
efficiency
—Fora um pump: P"' P
P
2.3.9.3 Efficiency — Fora turbine: —
Y n= — = n
nh'nm
h
.:1,'
—For a pump: n
=
=nh'nm
2.3.9.4 Relative Ratio of the efficiency at any given operating
tiret
efficiency condition to a reference value
—
2.3.9.5 Weighted average The efficiency calculated from the formula:
nw
efficiency
w2 /2
+ "'
w1 7/1 + 7 + W3 773
=
/pi +w2.+ w3+.
where n1 , 71 , . are the values of efficiency at
2 , 773
d , w
specified operating conditions an w1 , w2 3 , .
are their agreed weighting factors respectively
—
2.3.9.6 Arithmetic The weighted average efficiency (2.3.9.5) with
n a
average w1 = w2 = w3 = • • •
efficiency
The disk friction losses and leakage losses (volumetric losses) are considered as hydraulic losses in the formulae in 2.3.9.1. The
'
"disk friction losses" are the friction losses of the outer surfaces of the runner/impeller not in contact with the active flow.

41 © IEC — 49 —
Pump
Turbine
Coupling of the runner/impeller
and the shaft
IEC 373/9I
Turbine Pump
e
+q^r =e+ ^
4 =q' q
= Qm - q
(2 1 =Qm+q Q 1
Q), assuming Ph = E (e Q) 1 assuming LPh =0 Ph = E • (e • OPh =0
P = Pm — PL., assuming = 0 P = Pm Pi, ,n assuming Pt =0
P1 +
Q1
Volumetric efficiency ^„ = Q`"
Q 1 Q m
Pm P
h
I-lydraulic efficiency') —
=
nh 77h pm
Ph
Ph
Efficiency = P—
r) n = P
Ph
The formulae ignore the compressibility of the water.
1) The disk friction losses and leakage losses (volumetric losses) a re considered as hydraulic losses in this formula. This "disk
friction losses" are the friction losses of the outer surfaces of the runner/impeller not in contact with the active flow Qm.
Figure 9 —Flux diagram for power and discharge (example)

41© IEC
51 —
—
3. Nature and extent of hydraulic performance guarantees
3.1 General
3.1.1 A contract for a regulated or non-regulated* machine should contain guarantees covering at least power,
discharge, efficiency (see 3.2.5), maximum momentary overspeed and maximum/minimum momentary
pressure, maximum steady state runaway speed (reverse runaway speed in case of a pump).
In the case of a pump the guarantees may also cover the maximum zero-discharge specific hydraulic
energy (head)
and the zero-discharge power, the latter one with impeller rotating in water and/or in air, for
the specified speed.
These guarantees are considered as main hydraulic guarantees (see 3.2) and fall within the scope of this
standard. Other guarantees (see 3.3) are not covered by this standard.
3.1.2 The purchaser shall arr
ange for the supplier of the machine to be provided with true, full and acceptable
data covering all basins, inlet and outlet st
ructures, waterways between the points of intake and discharge
and all parts and equipment relating thereto, all the driven or driving machinery whether electric or not and
the revolving parts thereof, and all governors, valves, gates and
allied mechanisms.
3.1.3 The purchaser shall be responsible for specifying the values of all the parameters on which guarantees
are based, including water quality and temperature**, specific hydraulic energies of the pl ant (see 2.3.6.4)
and specific hydraulic energy losses (see 2.3.6.6), for the study of the plant, particularly the correct inlet
and outlet conditions of the machine and for the co-ordination of what concerns the interaction between
the machine and the waterways. Should the operational and guaranteed ranges differ, he shall indicate the
limits of the operation.
3.1.4 If the electric generator or motor is to be used for measuring turbine or pump power (see 2.3.8.3), such
electric generator or motor and its auxiliaries shall be given appropriate tests. It should be a condition of
the contract that the supplier of the hydraulic unit or his representative shall have the right to be present
at such tests. A certified copy of the generator or motor test calculations and results shall be given to the
supplier of the hydraulic machine.
3.2 Main guarantees
3.2.1 Practical plant operation
Practical plant operation usually involves some va riation in specific hydraulic energy (head). Therefore
specifications shall state the specific hydraulic energies to which guarantees shall apply.
For practical reasons a transient test may not be conducted at the same time as a steady-state perform ance
test.
* A regulated machine is a machine in which the flow is controlled by a flow-controlling device such as guide vanes, needle(s),
and/or runner/impeller blades. A single regulated machine is a regulated machine with one flow-controlling device; a double regulated
machine is a regulated machine with two flow-controlling devices. A non-regulated machine is a machine in which no flow-controlling
device is provided.
** If the water temperature during the acceptance test is significantly different from the specified value (e.g. more than 10°C),
the relev an
t scale effect should be taken into account.

41©IEC — 53 —
3.2.2 Power
Power guarantees may be required at one or more specified speeds for:
a) a regulated turbine: power to be reached at one or more specified specific hydraulic energies (see Figure
10 a);
b)
a non-regulated turbine: power to be reached and power not to be exceeded over a specified specific
hydraulic energy range* (see Figure 10 b);
c) a non-regulated/regulated pump: power not to be exceeded over a specified specific hydraulic energy
range (see Figure 10 c).
3.2.3 Discharge
Discharge guarantees may be required at one or more specified speeds for.
a)
a regulated turbine: discharge to be reached at one or more specified specific hydraulic energies (see
Figure 10 a);
b) a non-regulated turbine: discharge to be reached over a specified specific energy range (this guarantee
is usually replaced by the corresponding power guarantee, see 3.2.2 b) and discharge not to be exceeded
(see Figure 10 b);
c)
a non-regulated/regulated pump: discharge over a specified specific hydraulic energy r a
...