Field acceptance tests to determine the hydraulic performance of hydraulic turbines, storage pumps and pump-turbines

Specifies methods for any size and type of impulse or reaction turbine, storage pump or pump turbine. Determines whether the contract guarantees have been fulfilled and deals with the rules governing these tests as well as the methods of computing the results and the content and style of the final report.

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

Spécifie les méthodes d'essai applicables à toutes les turbines à action ou à réaction, pompes d'accumulation et pompes turbines, quels que soient leurs dimensions et leur type. Permet de déterminer si les garanties contractuelles sont respectées. Elle fixe les règles de conduite de ces essais ainsi que les méthodes de calcul des résultats, le contenu et le mode de présentation du rapport final.

Terenski prevzemni preskusi za ugotavljanje zmogljivosti vodnih turbin, akumulacijskih črpalk in črpalnih turbin (IEC 60041:1991, spremenjen)

General Information

Status
Published
Publication Date
28-Feb-2001
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Mar-2001
Due Date
01-Mar-2001
Completion Date
01-Mar-2001

RELATIONS

Buy Standard

Standard
SIST EN 60041:2001
English language
216 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day

Standards Content (sample)

SLOVENSKI STANDARD
SIST EN 60041:2001
01-marec-2001
1DGRPHãþD
SIST IEC 60041:1999
7HUHQVNLSUHY]HPQLSUHVNXVL]DXJRWDYOMDQMH]PRJOMLYRVWLYRGQLKWXUELQ
DNXPXODFLMVNLKþUSDONLQþUSDOQLKWXUELQ ,(&VSUHPHQMHQ

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
SIST EN 60041:2001 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 60041:2001
---------------------- Page: 2 ----------------------
SIST EN 60041:2001
---------------------- Page: 3 ----------------------
SIST EN 60041:2001
---------------------- Page: 4 ----------------------
SIST EN 60041:2001
---------------------- Page: 5 ----------------------
SIST EN 60041:2001
---------------------- Page: 6 ----------------------
SIST EN 60041:2001
---------------------- Page: 7 ----------------------
SIST EN 60041:2001
---------------------- Page: 8 ----------------------
SIST EN 60041:2001
INTERNATIONAL IEC
STANDARD
60041
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

PRICE CODE
Commission Electrotechnique Internationale
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue
---------------------- Page: 9 ----------------------
SIST EN 60041:2001
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
109
7. Test conditions and procedure
109
7.1 Test conditions
111
trumentation 7.2 Test procedure and ins
---------------------- Page: 10 ----------------------
SIST EN 60041:2001
41© IEC -5 -
Page
Clause
111
8. Computation and analysis of results
111
8.1 Conversion of results
113
8.2 Comparison with guarantees
SECTION FOUR - METHODS OF MEASUREMENT
9. Introduction 115
115
9.1 Efficiency
115
9.2 Hydraulic power
119
9.3 Mechanical power
119
10. Discharge
119
10.1 General
123
10.2 Current-meter method
145
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
213
11.3 Determination of the net positive suction specific energy
217
11.4 Pressure measurements
241
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
285
12.3 Bearing losses
291
13. Rotational speed
291
13.1 General
291
13.2 Speed measurements in the case of direct measurement of power
291
13.3 Speed measurements in the case of indirect measurement of power
291
13.4 Uncertainty of measurement
14. Thermodynamic method for measuring efficiency 293
293
14.1 General
293
14.2 Efficiency and specific mechanical energy
295
14.3 Procedure for measurement of specific mechanical energy
305
14.4 Apparatus
309
14.5 Test conditions to be fulfilled
313
14.6 Corrective terms
319
14.7 Uncertainty of measurement
---------------------- Page: 11 ----------------------
SIST EN 60041:2001
41 © IEC 7
Page
Clause
321
15. Index tests
15.1 General 321
323
15.2 Relative discharge measurement
15.3 Measurement of other quantities 331
15.4 Computation of results 331
333
15.5 Uncertainty of measurement
337

APPEr\TDIX A — Systematic uncertainties in performance measurements at steady state conditions

353
APPENDIX B — Rejection of outliers
355

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
369
APPENDIX E — Physical data
391

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

395
measuring system

APPENDIX H — Thermodynamic method — Examples for a balance of power and computation of the

399
specific mechanical energy
405
APPENDIX J — Acoustic method of discharge measurement
---------------------- Page: 12 ----------------------
SIST EN 60041:2001
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

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

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.
193
Amendment No.1 (1977).
193A (1972): First supplement.

(1970): International code for testing of speed governing systems for hydraulic turbines.

308
(1976): International code for model acceptance tests of storage pumps.
497

(1976): Guide for commissioning, operation and maintenance of hydraulic turbines.

545

(1978): Cavitation pitting evaluation in hydraulic turbines, storage pumps and pump-turbines.

609
ce of storage pumps and of pump-turbines
(1985): Guide for commissioning, operation and mainten an
805
operating as pumps.
---------------------- Page: 13 ----------------------
SIST EN 60041:2001
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

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

5167
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.
---------------------- Page: 14 ----------------------
SIST EN 60041:2001
—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

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.

---------------------- Page: 15 ----------------------
SIST EN 60041:2001
— 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

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.
---------------------- Page: 16 ----------------------
SIST EN 60041:2001
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
—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
---------------------- Page: 17 ----------------------
SIST EN 60041:2001
— 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.
---------------------- Page: 18 ----------------------
SIST EN 60041:2001
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)
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)
Values for air are given in 0, kg • m-3
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
factor property. Values for water are given
in Appendix E, Table EV
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
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 ,
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
---------------------- Page: 19 ----------------------
SIST EN 60041:2001
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

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 •

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
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
measurement (see Clause 15) -
m . s-1
2.3.4.8 Mean velocity Discharge divided by the area v
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)
---------------------- Page: 20 ----------------------
SIST EN 60041:2001
41©IEC —25 —
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
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)
2.3.5.6 Momentary The highest/lowest gauge pressure which occurs at a
p; Pa
pressure specified point of the system under specified transient
conditions (see Figure 4)
2.3.5.7 Maximum/ The momentary pressure under the most unfavourable
P, max
– Pa
minimum transient condition
m min
momentary
pressure
---------------------- Page: 21 ----------------------
SIST EN 60041:2001
41 © IEC —
27 —
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
IEC 366191
Figure 4b — Variation of pressure at the pump high p ssure
reference section during a power failure
---------------------- Page: 22 ----------------------
SIST EN 60041:2001
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

in use because it is very common. Therefore both related energy terms are listed, the specific energy terms

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
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.2^4 93294
with -J. and
The water density at ambient pressure may be
assumed as

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.
---------------------- Page: 23 ----------------------
SIST EN 60041:2001
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
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
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
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.
 Figure 6 shows the relationship between geodetic height of plant
---------------------- Page: 24 ----------------------
SIST EN 60041:2001
33 —
41 © IEC —
Symbol Unit
Sub-clause Term Definition
IILs = TE 's "Ls
2.3.7.7 Suction head loss
see 2.3.6.7
For definition of ELs ,
Suction height Zs = — (see Figure 7) Zs
2.3.7.8
For definition of Es , see 2.3.6.8
NPSE
NPSH
2.3.7.9 Net positive NPSH =
suction head 92
see 2.3.6.9
For definition of NPSE,
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
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.