SIST EN 60308:2005

SLOVENSKI SIST EN 60308:2005
STANDARD
september 2005
Vodne turbine – Preskušanje krmilnih sistemov (IEC 60308:2005)
Hydraulic turbines – Testing of control systems (IEC 60308:2005)
ICS 27.140 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 60308
NORME EUROPÉENNE
EUROPÄISCHE NORM June 2005
ICS 27.140
English version
Hydraulic turbines –
Testing of control systems
(IEC 60308:2005)
Turbines hydrauliques –  Wasserturbinen –
Essais des systèmes de régulation Prüfung von Regelsystemen
(CEI 60308:2005) (IEC 60308:2005)

This European Standard was approved by CENELEC on 2005-05-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 60308:2005 E
Foreword
The text of document 4/199/FDIS, future edition 2 of IEC 60308, prepared by IEC TC 4, Hydraulic
turbines, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 60308 on 2005-05-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2006-02-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2008-05-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60308:2005 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 60308:2005
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60041 (mod) 1991 Field acceptance tests to determine the EN 60041 1994
hydraulic performance of hydraulic
turbines, storage pumps and pump-
turbines
IEC 60193 1999 Hydraulic turbines, storage pumps and EN 60193 1999
pump-turbines - Model acceptance tests

1)
IEC 60545 - Guide for commissioning, operation and - -
maintenance of hydraulic turbines

IEC 61362 1998 Guide to specification of hydraulic turbine EN 61362 1998
control systems
1)
2)
IEC 61000-4-2 - Electromagnetic compatibility (EMC) EN 61000-4-2 1995
Part 4-2: Testing and measurement
techniques - Electrostatic discharge
immunity test
1) 2)
IEC 61000-4-3 - Part 4-3: Testing and measurement EN 61000-4-3 2002
techniques - Radiated, radio-frequency,
electromagnetic field immunity test

1)
IEC 61000-4-6 - Part 4-6: Testing and measurement - -
techniques - Immunity to conducted
disturbances, induced by radio-frequency
fields
ISO 4406 1999 Hydraulic fluid power - Fluids - Method for - -
coding the level of contamination by solid
particles
1)
Undated reference.
2)
Valid edition at date of issue.

NORME CEI
INTERNATIONALE IEC
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2005-01
Turbines hydrauliques –
Essais des systèmes de régulation
Hydraulic turbines –
Testing of control systems
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60308 © IEC:2005 – 3 –
CONTENTS
FOREWORD.7
INTRODUCTION.11
1 Scope and object.13
2 Normative references.13
3 Terms and definitions, symbols and units .15
4 Functions and components of hydro control systems .23
4.1 Control systems proper.23
4.2 Other control systems and transitions.23
4.3 Control system components .23
4.4 Safety functions, 4.14 of IEC 61362 .25
4.5 Environmental protection, 4.16 of IEC 61362.25
4.6 Electromagnetic compatibility (EMC).25
5 Contractual stipulations.25
5.1 Guarantees and acceptance tests .25
5.2 Documentation.25
6 Control system tests .27
6.1 General.27
6.2 Recommendations on workshop tests .27
6.3 Recommendations on field tests.29
6.4 Electrical checks.31
6.5 Test of converters, amplifiers and actuators .35
6.6 Site tests of controller characteristics.49
6.7 Safety tests.57
6.8 Test conditions to be fulfilled .61
6.9 Isolated network field tests .65
6.10 Role of controller for stability in interconnected power systems.69
7 Inaccuracies in controller tests.71
8 Simulation of governing and control operations .77
8.1 General remarks.77
8.2 Simulator characteristics.79
8.3 Inaccuracy of plant simulators, calculations of pressure surge and control
parameters.79
Annex A (informative) Test procedures.83
Annex B (informative) Recommendation for testing of turbine controllers .91
Annex C (informative) Field test of control systems.113
Annex D (informative) Control system test examples .119
Figure 1 – Servomotor cushioning time T .15
h
Figure 2 – Turbine control transmission ratio .17
Figure 3 – Controlled system self-regulation factor .19
Figure 4 – Oil flow Q function of input current I and pressure drop ∆p.35
Figure 5 – Electro hydraulic converter for high grade control system .37

60308 © IEC:2005 – 5 –
Figure 6 – Output stroke ∆s of a converter versus input current I.39
Figure 7 – Performance curves of control valves.43
Figure 8 – Example of on-line simulated isolated grid test.69
Figure D.1 – Insensitivity test under speed control with X-Y recording.141
Figure D.2 – Insensitivity test under power control with time characteristics .143
Figure D.3 – Flutter test of 2 regulated quantities with X-Y recording .145
Figure D.4 − Measurement of a unit step response with PID speed controller .147
Figure D.5 – Measurement of a unit step response with speed control for determination
of PID controller parameters .149
Figure D.6 – Measurement of unit step response in isolated operation .151
Figure D.7 – Measurement of a unit step responses with power control (Pelton turbine) .153
Figure D.8 − Measurement of unit step responses with power control (pump turbine) .155
Figure D.9 – Measurement of a unit step response with power control for determination
of PI-controller parameters.157
Figure D.10 – Measurement of a unit step response with head race level control.159
Figure D.11 – Measurement of the unit step responses with head race level control in
multi-unit operations .161
Figure D. 12 – Measurement of a load rejection with transition into no-load operation .163
Figure D.13 – Measurement of a load rejection with limit control of surge and suction
waves and with transition into no-load operation.165
Figure D.14 – Measurement of a start-up process under load .167
Figure D.15 – Measurement of changeover from full turbine load to synchronous
condenser operation .169
Figure D.16 – Measurement of a power step response in on-line simulated isolation test.171

60308 © IEC:2005 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HYDRAULIC TURBINES –
TESTING OF CONTROL SYSTEMS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60308 has been prepared by IEC technical committee 4: Hydraulic
turbines.
This second edition cancels and replaces the first edition published in 1970. This second
edition constitutes a technical revision.
The following is an explanation of the reasons for issuing a new edition.
For the testing of control systems, only the first edition of this standard (IEC 60308:1970,
International code for testing of speed governing systems for hydraulic turbines) was available
up till now. It was limited – as the name suggests – to speed governing. It is, therefore, the
intention of this second edition to expand the scope to include further functions of the overall
control system of hydro turbines. The scope of acceptance tests of such a system depends on
the guarantees stipulated in the specifications of a contract.

60308 © IEC:2005 – 9 –
Since new control concepts/algorithms are becoming more and more important besides and
beyond the PID principle, the following clauses do not refer to a specific algorithm (as did the
first edition of this standard).
It is noted that the testing of specific properties and the drawing-up of the corresponding
documentation involves costs which rise with increasing scope and the accuracy of the work
to be done. Therefore, a test should be limited to parameters, components and characteristics
which are indispensable for reliable and safe operation. Also the prescribed accuracy of
measurements should correspond to the requirements of operation. The code therefore
distinguishes in certain clauses the specific requirements for certain applications (for
example, peak load, base load, frequency control operation, etc.).
This standard is closely related to the IEC 61362.
The text of this standard is based on the following documents:
FDIS Report on voting
4/199/FDIS 4/209/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
60308 © IEC:2005 – 11 –
INTRODUCTION
The control functions of water turbines have undergone far-reaching changes and at the same
time gained in importance during the last few decades. This is shown in the fact that a new
standard has been developed: i.e. IEC 61362.

60308 © IEC:2005 – 13 –
HYDRAULIC TURBINES –
TESTING OF CONTROL SYSTEMS
1 Scope and object
This International Standard deals with the definition and the characteristics of control systems
and is the basis for tender documents and technical tenders. It is not limited to the actual
controller tasks but also include other tasks which may be assigned to a control system, such
as for instance sequence control tasks, safety, provision for the actuating energy.
The testing of control systems for hydro turbines can generally fulfil the following tasks:
– verification of system characteristics as per contract specification;
– verification of general proper functioning in the workshop and/or on site;
– tests to prove the fulfilment of guarantees;
– assessment of the actual state of an existing control system with regard to the question of
repair or replacement.
This standard covers the following systems:
– speed, power, opening, water level and flow control for all turbine types;
– electronic, electrical and fluid power devices;
– safety devices;
– start-up, shutdown devices etc.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60041:1991, Field acceptance tests to determine the hydraulic performance of hydraulic
turbines, storage pumps and pump-turbines
IEC 60193: 1999, Hydraulic turbines, storage pumps and pump-turbines − Model acceptance
tests
IEC 60545, Guide for commissioning, operation and maintenance of hydraulic turbines
IEC 61362: 1998, Guide to specification of hydraulic turbine control systems
IEC 61000-4-2, Electromagnetic compatibility (EMC) – Part 4-2: Testing and measurement
techniques – Electrostatic discharge immunity test
IEC 61000-4-3, Electromagnetic compatibility (EMC) – Part 4-3: Testing and measurement
techniques – Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-6, Electromagnetic compatibility (EMC) – Part 4-6: Testing and measurement
techniques – Immunity to conducted disturbances, induced by radio-frequency fields

60308 © IEC:2005 – 15 –
ISO 4406: 1999, Hydraulic fluid power − Fluids − Method for coding the level of contamination
by solid particles
3 Terms and definitions, symbols and units
For the purposes of this document, the following terms and definitions, symbols and units, as
well as the terms and definitions, symbols and units given in IEC 61362, apply.
Sub- Relative
Term Definition Quantity Unit
clause quantity
3.1 General definitions
∆n rev/min
3.1.1 speed deviation at a considered instant, the difference x
n
∆ω rad/s
between the actual speed of rotation and a
reference speed
∆f Hz
3.2 Performance under
major disturbances
3.2.1 servomotor elapsed time during which the rate of T s
h
cushioning time servomotor travel is retarded beginning at
a specified servomotor position to full
closed position (see Figure 1)
3.2.2 servomotor force net opening and/or closing force generated F N
by the servomotor when supplied with oil at
the minimum specified pressure
NOTE When penstock water pressure is
used to provide the closing force, the head
at which the servomotor shall be rated
should be stated. For spring operated
servomotors it is the net force exerted by
the servomotor when the spring is at its
maximum extended position
3.2.3 servomotor product of the maximum servomotor stroke
F × Y J = N⋅m
M
capacity and the force as described under 3.2.2
Y/Y
max
T
q
1,0
T
h
T
f t
IEC  036/05
Figure 1 – Servomotor cushioning time T
h
60308 © IEC:2005 – 17 –
Sub- Relative
Term Definition Quantity Unit
clause quantity
3.3 Terms relating to
the controlled
system
3.3.1 controlled system system controlled by the governing system
consisting of the hydraulic turbine, its
water supply and discharge passages, the
generator with voltage regulator and the
electric power network to which it is
connected
3.3.2 torque deviation power output deviation divided by ∆M N⋅m m
instantaneous angular speed
3.3.3 unit acceleration ratio of the angular momentum of the unit T s
a
constant to the guarantee torque
T
3.3.4 load acceleration ratio of the angular momentum, caused by s
b
constant the network referred to the guaranteed
torque of the unit
e
3.3.5 turbine control At a considered servomotor position, the
y
transmission ratio slope of the graph relating to the turbine
torque m at constant speed and head to
t
servomotor movement y (see Figure 2)
d(M M ) dm
t r t
e = =
y
dy dy
3.3.6 speed regulation graph showing the relative speed as a
graph
P
function of the relative power p = ,
P
r
when the controller is in equilibrium and
the command signal is constant
m
t
1,0
e
y
1,0
0 Y/Y
max
IEC  037/05
Figure 2 – Turbine control transmission ratio

60308 © IEC:2005 – 19 –
Sub- Relative
Term Definition Quantity Unit
clause quantity
3.3.7 permanent speed slope of the speed regulation graph at a e
p
regulation specific point of operation
dx
n
e = −
p
dx
p
3.3.8 maximum power difference between the relative speeds e
s
change speed read from the speed regulation graph at
regulation zero power and rated power
e
3.3.9 controlled system at the speed considered, the slope of the
n
self-regulation graph relating to the torque deviation to
factor the speed at a specified servomotor
position and a specified load condition of
the network. The torque should be referred
to the rated torque P /ω and the speed
r r
referred to the rated speed ω
r
(see Figure 3)
3.3.10 turbine self- component of e due to the turbine e
n t
regulation factor
dm
t
e =
t
dx
n
P and ω are the same values as used to
r r
determine e (see Figure 3)
n
3.3.11 load self-regulation component of e due to the load e
n g
factor
dm
Ȧ d(P/Ȧ)
g
r
e = = ×
g
dx P dx
n r n
P and ω are the same reference values
r r
as used to determine e (see Figure 3)
n
m
m
g
e
g
e
n
0 0
e
t
m
t
0 1,0
x
n
IEC  038/05
Figure 3 – Controlled system self-regulation factor

60308 © IEC:2005 – 21 –
Sub- Relative
Term Definition Quantity Unit
clause quantity
3.3.12 network load coefficient expressing the ratio of relative torque e
b
characteristic variation of the load to the relative speed variations.
The value to which the power variations, ∆P, to be
referred is the actual power, P , absorbed by the
network. For practical purposes, the constant, e , is
b
obtained from the formula:
∆P / P
e = −1
b
x
n
3.3.13 penstock time required for the pressure waves to travel 2 lengths T s
r
reflection time of the penstock:
n
L
i
T = 2
¦
r
a
i = 1 i
where
a is the velocity of wave propagation in each section of
i
the penstock;
L is the length of each penstock section
i
a)
3.3.14 water inertia time characteristic time at rated condition due to inertia of T s
W
the water in the water passages defined as:
n
Q L
r i
T =
W ¦
gH A
r i
i=1
where
A is the area of each section;
i
L is the corresponding length;
i
Q is the rated discharge;
r
H is the rated head;
r
g is the acceleration due to gravity
3.3.15 water hammer ratio of water inertia time, T , to penstock reflection h
W W
number time, T at guaranteed conditions.
r
(Allievi constant)
T
W
h =
W
T
r
maximum
3.3.16 maximum momentary change of speed, when a rev/min
∆n
max
momentary
specified load is suddenly changed (see IEC 60041)
speed variation rad/s
∆ω
max
Hz
∆f
max
maximum
3.3.17 maximum momentary pressure variation, when a ∆H Pa
max
momentary
specified load is suddenly changed (see IEC 60041)
pressure variation
a)
Can be calculated for different conditions.

60308 © IEC:2005 – 23 –
4 Functions and components of hydro control systems
In this clause, the functions and components are listed, which may be subjected to tests and
verifications.
NOTE Again reference is made to IEC 61362 for explanation and definition.
4.1 Control systems proper
4.1.1 Primary modes
Standard   Subclause
The primary modes are the following:
– speed control (no-load and synchronising, IEC 61362 3.1.1
isolated operation)
– power control IEC 61362 3.1.2
– opening control IEC 61362 3.1.3
4.1.2 Secondary modes
The secondary modes are the following:
– water level control or positioning IEC 61362 3.1.3
(opening) control
– flow control IEC 61362 4.15.4
– optimisation control (station control) IEC 61362 4.9
4.2 Other control systems and transitions
The other control systems and transitions are the following:
– surge control IEC 61362 4.15.2
– pressure control IEC 61362 4.15.1 and 4.15.3
– start up and synchronisation IEC 61362 4.13.1
– shutdowns and load rejections IEC 61362 4.13.2
– transitions between different control modes
4.3 Control system components
The control system components are the following:
– electro-hydraulic and electro-mechanical converters
– control valves
– servomotors
– pressure oil supply systems and IEC 61362 4.11
energy storage mechanisms
(accumulators, weights, springs)
– auxiliary power supply for electrical/electronical systems

60308 © IEC:2005 – 25 –
4.4 Safety functions, 4.14 of IEC 61362
The safety functions are the following:
– safety shutdown
– overspeed protection
– interlocks
– creep detection
4.5 Environmental protection, 4.16 of IEC 61362
For control systems, the following aspects are relevant:
– vibrations
– climatic conditions
4.6 Electromagnetic compatibility (EMC)
For control systems, the following aspects are relevant:
– electromagnetic compatibility IEC 61362 4.17
– electrical interference sources
5 Contractual stipulations
5.1 Guarantees and acceptance tests
In the process of verifying guarantees set up according to IEC 61362, the following is
recommended in case of new control systems for new plants as well as for existing power
plants:
– establish the characteristics of the controlled system;
– establish scope of control system tests to verify guarantees and scope of documentation
(see 5.2);
– stipulate measures to be taken in the event of failure to comply with guarantees.
In the process of verifying the actual state of an existing control system, only measurements
which allow the assessment of the most important basic properties, for example isolated
network operation will be performed.
A test manager is to be made responsible for the test procedure, the recording and
documentation of results. The extent and the format of the documentation are to be agreed
upon beforehand.
5.2 Documentation
For every test, the following shall be documented:
– instrument parameters;
– list of measured variables;
– limit values;
– test conditions;
– test procedure;
– test results.
60308 © IEC:2005 – 27 –
Careful documentation is particularly important if certain tests are to be repeated at given time
intervals (for example for authorities, insurance companies, restarts after revision, etc.). Care
has to be taken in order to avoid environmental hazards.
The measured values can be recorded and processed either:
– by using suitable recording instruments with subsequent manual evaluation, or
– on line by a directly connected computer with the printouts forming an integral part of the
documentation.
In the case of initial start-ups, a final report should demonstrate that
– the unit is operating according to specification;
– the safety requirements are fulfilled;
– the specific contractual guarantees are fulfilled.
6 Control system tests
6.1 General
In order to keep the commissioning period as short as possible, it is recommended that the
largest part possible of the required contractual tests be carried out in the manufacturer’s
works (workshop tests). The on site tests should be limited to the demonstration of such
characteristics, which:
– are indispensable for the safety, and
– which cannot be carried out without the generating unit and the pressure supply system.
In the following subclauses, some basic aspects are summarised.
6.2 Recommendations on workshop tests
The scope of the tests, the best set up and the extent of the documentation should be
stipulated in the contract in accordance with requirements. Thereby type tests, including EMC
type tests with certificates shall be considered. It should be stipulated, who will witness the
tests.
For workshop tests, it is not necessary to set up all components in a complete loop, the
following subsystems (which may be different makers’ responsibility) can rather be tested
separately:
– cabinet with plug-in units for control;
– servo-positioners, control valves with a test servomotor if necessary;
– oil pressure supply systems.
In this case, signals at interfaces between separately tested equipment shall be clearly
defined and measurable.
It is appropriate to arrange for the simulation of simple circuits to test subsystems and/or to
employ a plant simulator if available to test the complete control process for overall
performance.
Individual testing of components and/or subsystems may not be needed in case the complete
system is assembled.
60308 © IEC:2005 – 29 –
6.3 Recommendations on field tests
6.3.1 New control systems
For control systems, the following measures and steps apply.
– Safety devices, displays, alarms and trip settings should be verified prior to conducting
field tests of control systems.
– Commissioning of the complete generating unit has to be performed including load
rejection tests as per IEC 60041:1991 and the testing of control systems shall be co-
ordinated with the commissioning of Hydro generating equipment. Refer to IEC 60545.
For the actual control system tests:
– The relevant mode to be checked is set, such as no-load, isolated network operation,
frequency-power control or level control; subsequently defined test signals are
superimposed and resulting changes for the specified values through the entire operating
range are observed/recorded, whereby control settings can be optimised during the
process. The results of such tests can be used as baseline values in order to be compared
with the results of maintenance tests which are carried out during the life of the
equipment.
– The insensitivity of the controller can be checked; this test is only needed when the power
station will be participating in primary regulation of network frequency, especially in peak
load power stations, also in power stations with a distinct requirement for high control
accuracy (for recommended insensitivities, see 4.3.2 of IEC 61362, acceptable measuring
uncertainties are given in Clause 7).
– Controller parameters can be determined. If the guaranteed behaviour is not achieved and
the reason for this has to be identified, then other functions influencing the control system
behaviour shall be examined. These functions may include: masses, generator-load
characteristics and the influence of regulator forces on actuating times. In certain cases,
the determination of the controller parameters and of the turbine transfer function may be
used to provide models of the power plant, in order to carry out analytical studies of the
dynamic behaviour of the power system.
– The turbine characteristics of pump turbines may need to be determined in detail in order
to provide a basis for a reliable control strategy.
6.3.2 Existing control systems
6.3.2.1 Indication of control deficiencies
Deficiencies in existing control systems may have the following effects:
– long settling times of the controlled variable;
– long synchronisation times, excessive damping;
– drifting operating points;
– changes in actuator speeds;
– unusual oscillations (in no-load and/or isolated operation, etc.);
– excessive insensitivities and/or hysteresis effects;
– excessive leakages (pumping period, oil temperature, etc.).

60308 © IEC:2005 – 31 –
6.3.2.2 Identification of deficiencies
The following checks can be made:
– measurement of the insensitivity;
– recording of step responses/transient functions (unit step responses) by applying defined
signals at the input (command signal, controlled variable, frequency, etc.);
– indexing the servomotors;
– checking the runner/guide vane relationship in Kaplan turbines;
– checking the deflector/nozzle relationship in Pelton turbines;
– identifying possible resonances (draft tube, generator etc.);
– measurements to check the plant parameters;
– checking of the overall safety of the hydraulic conduit and the pipe-installation.
6.3.2.3 Deciding whether to replace or to repair existing control systems
The above-mentioned checks will in almost all cases give information on the reasons why the
deficiencies occur, allowing to decide on the measures to be taken, such as for instance:
– verification of the reliable operation of existing equipment for retention;
– overhauling of individual components;
– replacement of components or of complete control systems;
– changes in the configuration;
– risks and consequences of oil leakage.
Besides the above-mentioned points, the following facts may also influence the decision to
replace or repair existing elements or systems:
– the assessment of operating costs;
– the assessment of repair costs;
– the operating and efficiency improvement potential of replacement versus repair;
– general safety and any demands required by authorities.
6.4 Electrical checks
6.4.1 General
Whereas the electrical components of the mechanical turbine controller include control valves,
servomotors, pump and pendulum (ballhead) drives, the electronic controller already carries
out all control functions including pilot control.
Electronic systems are sensitive to electrical-magnetic interference. Therefore, the following
shall be given special attention:
– quality of the power supply;
– overvoltage protection;
– filter and shielding measures;
– immunity of the components to interference.

60308 © IEC:2005 – 33 –
If certain basic safety measures are taken and guidelines adhered to, testing can concentrate
on checking the control systems for proper functioning. Electrical checking is expensive and
requires qualified personnel as well as special testing equipment (for example for measuring
transient overvoltages, storage oscilloscopes with an upper cut-off frequency of 100 MHz are
required). Electrical checking is usually performed in the form of type tests. For specifications
of the electromagnetic compatibility (EMC) tests refer to IEC 61000-4-2, IEC 61000-4-3 and
IEC 61000-4-6.
6.4.2 Selection of test center
To carry out the functional checks on site, a centrally located, quiet place (control room)
should be selected where all important signals of the process are available.
If the controller is not located near the generating unit, provision for local emergency
operation should be made.
6.4.3 Power supply
The check of the power supply with volt- and amperemeter, oscilloscope or transient recorder
should normally be carried out in the workshop and is generally limited to
– tolerance limits and ripple factor;
– current input;
– test of switch-over of the supply voltage and set-in of a redundant voltage of stored energy
time after power failure and re-closing behaviour (for small and simple systems, these
tests can be reduced);
– failure monitoring.
6.4.4 Overvoltage protection and suppression of interference voltage
The following may be checked:
– certification of the electronic equipment with respect to EMC;
– the electric isolation of the power supply unit for withdrawable electronic parts;
– the contact separation of the binary and analogue signals during take-over and/or transfer;
– shielding of the cables to the peripheral devices;
– the physical separation of the signal cables from power lines;
– earthing of inactive metal parts;
– protection of the peripheral devices against overvoltages by protective elements;
– wiring of inductive devices (relay coils, solenoid valves) with extinguishing elements (free-
wheeling diode, RC combination, etc.).
Ground connections are to be tested with ohmmeters. In the event of interferences, a
measurement is to be carried out at the ends of the signal cables with an oscilloscope.

60308 © IEC:2005 – 35 –
6.4.5 Test of the process interface system
The electrical signals for actuator position, speed, power, flow, head (up-stream and tail race)
shall be checked for:
– open circuit characteristic and hysteresis (actuator position);
– zero drift and temperature sensitivity;
– interference;
– filtering (power, flow, water level);
– limit value acquisition;
– fault monitoring, if available.
6.5 Test of converters, amplifiers and actuators
6.5.1 Electrohydraulic and electromechanical converters
6.5.1.1 General
The converters dealt with here are the connecting element between the electronic and the
hydro-mechanical part of the control system. They are of great importance for the overall
behaviour of the control system. Therefore, sensitivity, precision (including temperature
stability) and also the dynamic behaviour shall exceed the corresponding properties of the
subsequent amplifier stages.
6.5.1.2 Electro hydraulic converters
(Examples: servo-valves, proportional valves.)
The most important characteristic is to establish the oil flow rate as a function of the
command signal and of the pressure drop.
Q  m /s
∆p  bar
I  mA
IEC  039/05
Figure 4 – Oil flow Q function of input current I and pressure drop ∆p
The curves of Figure 4 should be measured with various pressure differences and, in addition,
oil temperature and type of oil (viscosity grade) should be noted. The flow can be measured
by tank measurement or by using a test servomotor.
Further measurements may be taken to verify the dead time and the dynamic characteristics.

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NOTE 1 Multi-stage servo- and/or proportional valves often have an additional position controller for the second
stage and can therefore only be tested as a system including the corresponding electronic device.
NOTE 2 If an emergency trip and failsafe (for example shutdown in the event of power failure) are available, their
function should also be tested.
NOTE 3 Generally, to achieve the specified performance, a vibration (dither) signal is applied, which must also be
checked.
6.5.1.3 Electromechanical converters
In principle, these converters are electro-motor driven (rotating or linear). For hydro turbines
controlled by such electric actuators, they consist of electric motor, gearbox and operating
mechanism. These converters are, for instance, used for the direct actuation of the regulating
elements (guide vanes, runner blades, nozzle, deflector) or to drive control valve systems.
This type of actuator does not depend on the oil pressure system. It is generally suitable for
small hydro turbines, designed to withstand sustained runaway operation, in the event of the
total failure of electric supply. Suitable back-up protection shall be provided, to reduce the
turbine discharge to an acceptable level. Some examples of the protection are
– closing of guide vanes by self-closing characteristics;
– closing of inlet valve, with guide vanes open;
– counter weight or spring.
For testing purposes, measurement of current input and actuating times is usually sufficient.
Electronic
Feedback
amplifier
transducer
Y
=
P
T
To control
valve
IEC  040/05
Figure 5 – Electro hydraulic converter for high grade control system

60308 © IEC:2005 – 39 –
∆s
I
IEC  041/05
Figure 6 – Output stroke ∆s of a converter versus input current I
It is furthermore possible to check
– the dead time;
– the actuating forces as a function of the oil pressure;
– the dynamic characteristics.
During these checks, the corresponding vibration (dither) signal, oil losses, oil temperature
and oil viscosity should be recorded.
6.5.1.4 Two stage electromechanical/hydraulic control
In some control systems, electro mechanical/hydraulic converters can be composed of an
electro hydraulic converter (see 6.5.1.2), a small pilot servomotor and a position feedback,
(see Figure 5), the pilot servomotor will then actuate the main control (distributing) valve. For
measurement, no additional aspects have to be considered.
If these converters are designed as a compact device (for example as a plunger coil design)
with integrated hydr
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