SIST EN IEC 60308:2024

SLOVENSKI STANDARD
01-december-2024
Hidravlične turbine - Preskušanje krmilnih sistemov (IEC 60308:2024)
Hydraulic turbines - Testing of governing systems (IEC 60308:2024)
Wasserturbinen - Prüfung von Regelsystemen (IEC 60308:2024)
Turbines hydrauliques - Essais des systèmes de régulation (IEC 60308:2024)
Ta slovenski standard je istoveten z: EN IEC 60308:2024
ICS:
27.140 Vodna energija Hydraulic energy engineering
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 60308

NORME EUROPÉENNE
EUROPÄISCHE NORM November 2024
ICS 27.140 Supersedes EN 60308:2005
English Version
Hydraulic turbines - Testing of governing systems
(IEC 60308:2024)
Turbines hydrauliques - Essais des systèmes de régulation Wasserturbinen - Prüfung von Regelsystemen
(IEC 60308:2024) (IEC 60308:2024)
This European Standard was approved by CENELEC on 2024-10-28. 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 CEN-CENELEC
Management Centre 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 CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60308:2024 E
European foreword
The text of document 4/497/FDIS, future edition 3 of IEC 60308, prepared by TC 4 "Hydraulic turbines"
was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2025-11-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2027-11-30
document have to be withdrawn
This document supersedes EN 60308:2005 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60308:2024 was approved by CENELEC as a European
Standard without any modification.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60041 - Field acceptance tests to determine the EN 60041 -
hydraulic performance of hydraulic
turbines, storage pumps and pump-
turbines
IEC 60545 - Guidelines for commissioning and EN IEC 60545 -
operation of hydraulic turbines, pump-
turbines and storage pumps
IEC 61362 - Guidelines to specification of hydraulic EN IEC 61362 -
turbine governing systems
ISO 4406 - Hydraulic fluid power - Fluids - Method for - -
coding the level of contamination by solid
particles
IEC 60308 ®
Edition 3.0 2024-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Hydraulic turbines – Testing of governing systems

Turbines hydrauliques – Essais des systèmes de régulation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.140  ISBN 978-2-8322-9490-1

– 2 – IEC 60308:2024 © IEC 2024
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Recommendations on tests . 9
4.1 General . 9
4.2 Recommendations on workshop tests . 9
4.3 Recommendations on field tests . 9
4.3.1 New governing systems . 9
4.3.2 Existing governing systems . 10
5 Governing system tests . 11
5.1 Test conditions to be fulfilled . 11
5.1.1 General . 11
5.1.2 Turbine operation conditions . 11
5.1.3 Hydraulic pressure unit condition . 11
5.1.4 Deviation of values from specified operating conditions . 11
5.1.5 Provisions for instruments . 12
5.1.6 Calibration of instruments . 12
5.2 Electrical checks . 12
5.2.1 General . 12
5.2.2 Selection of test location. 13
5.2.3 Power supply . 13
5.2.4 Overvoltage protection and suppression of interference voltage . 13
5.3 Test of the process interface system . 13
5.4 Test of converters, amplifiers and actuators . 14
5.4.1 Electrohydraulic and electromechanical converters . 14
5.4.2 Servomotors . 18
5.4.3 Dead time, insensitivity . 19
5.4.4 Provision of actuating energy . 19
5.4.5 Oil leakage . 20
5.4.6 Test of the positioning loop . 20
5.5 Tests of governor characteristics . 21
5.5.1 General . 21
5.5.2 Test of the governing system . 21
5.5.3 Determination of governing system’s parameters . 21
5.5.4 Test of main control loops . 23
5.5.5 Considerations for island grid field tests . 25
5.6 Servomotor pressure indication test . 28
5.7 Safety tests . 28
5.7.1 General . 28
5.7.2 Test strategy . 28
5.7.3 Test plan . 29
6 Inaccuracies in tests of governing systems . 29
7 Simulation of governing and control operations. 32
8 Organizational aspects of test management . 32

IEC 60308:2024 © IEC 2024 – 3 –
Annex A (informative) Test procedures . 34
A.1 Insensitivity test procedure . 34
A.2 Dead time test procedure . 34
A.3 Test procedure for the servomotor pressure indication . 35
A.4 Procedure for the measurement of the pressure and flow characteristics of
control valves . 35
Annex B (informative) Recommendation for testing of turbine governing systems . 37
Annex C (informative) Field test of governing systems . 41
C.1 General . 41
C.2 Data on operating conditions . 41
C.3 Pre-start tests prior to filling waterways . 41
C.4 Test after filling waterways. 42
C.5 Initial run . 42
C.6 No-load tests . 42
C.7 Load and load rejection tests . 43
C.8 Measurement and recordings . 43
Annex D (informative) Governing system test examples . 44
D.1 General . 44
D.2 Insensitivity test under speed control with X-Y recording (example referring
to 5.5.3.3.3 and Clause A.1 b)) . 44
D.3 Insensitivity test under opening control with frequency-opening-droop and
time characteristics (example referring to 5.5.3.3.4 and Clause A.1 a) . 46
D.4 Insensitivity test under power control with time characteristics (example
referring to 5.5.3.3.4 and Clause A.1 a) . 48
D.5 Synchronism test of two controlled quantities with X-Y recording (example
referring to 5.5.3.4) . 50
D.6 Measurement of a unit step response with PID speed controller (example
referring 5.5.4.2 and 5.5.3.1) . 51
D.7 Measurement of a unit step response with speed control for determination of
PID controller parameters (example referring to 5.5.4.2; 5.5.3.1) . 53
D.8 Measurement of a unit step response with speed control for determination of
PID controller parameters (example referring to 5.5.4.2; 5.5.5) . 55
D.9 Measurement of a unit step response in island operation (example referring
to 5.5.5.3) . 57
D.10 Measurement of unit step responses with power control (example referring
to 5.5.4.3 and 5.5.4.6) . 59
D.11 Measurement of unit step responses with power control (example referring
to 5.5.4.3 and 5.5.4.6) . 61
D.12 Measurement of a unit step response with power control for determination of
PI-controller parameters (example referring to 5.5.4.3) . 63
D.13 Measurement of a unit step response with headwater level control (example
referring to 5.5.4.4) . 65
D.14 Measurement of the unit step responses with headwater level control, in
multi-unit operations (example referring to 5.5.4.4) . 67
D.15 Measurement of a load rejection with transition into no-load operation
(example referring to 5.5.4.2) . 69
D.16 Measurement of a load rejection with limit control of surge and suction
waves and with transition into no-load operation (example referring to
5.5.4.2) . 71
D.17 Measurement of a start-up process and loading (example referring to 5.5.4) . 73
D.18 Measurement of changeover from full turbine load to synchronous
condenser operation (example referring to 5.5.4) . 75

– 4 – IEC 60308:2024 © IEC 2024
D.19 Measurement of a power step-response in on-line simulated island operation
test (example referring to 5.5.4, 5.5.5) . 77

Figure 1 – Oil flow Q function of input current I and pressure drop ∆p . 14
Figure 2 – Two-stage electrohydraulic control with pilot servomotor . 15
Figure 3 – Output stroke ∆s of a converter versus input current I . 15
Figure 4 – Performance curves of control valves . 17
Figure 5 – Example of on-line simulated island grid test . 27
Figure D.1 – Insensitivity test under speed control with X-Y recording . 45
Figure D.2 – Insensitivity test under opening control with time characteristics . 47
Figure D.3 – Insensitivity test under power control with time characteristics . 49
Figure D.4 – Synchronism test of two controlled quantities with X-Y recording . 50
Figure D.5 – Measurement of a unit step response with PID speed controller . 52
Figure D.6 – Measurement of a unit step response with speed control for determination
of PID controller parameters . 54
Figure D.7 – Measurement of a unit step response with speed control for determination
of PID controller parameters . 56
Figure D.8 – Measurement of unit step response in island operation . 58
Figure D.9 – Measurement of a unit step responses with power control (Pelton turbine) . 60
Figure D.10 – Measurement of unit step responses with power control (pump-turbine) . 62
Figure D.11 – Measurement of a unit step response with power control for
determination of PI-controller parameters . 64
Figure D.12 – Measurement of a unit step response with headwater level control . 66
Figure D.13 – Measurement of the unit step responses with headwater level control in
multi-unit operations . 68
Figure D.14 – Measurement of a load rejection with transition into no-load operation. 70
Figure D.15 – Measurement of a load rejection with limit control of surge and suction
waves and with transition into no-load operation . 72
Figure D.16 – Measurement of a start-up process under load . 74
Figure D.17 – Measurement of changeover from full turbine load to synchronous
condenser operation . 76
Figure D.18 – Measurement of a power step response in on-line simulated island
operation test . 78

Table 1 – Unit and plant categories . 30
Table 2 – Admissible measuring instrument inaccuracies . 31
Table B.1 – Test plan for units for peak load operation, level I . 38
Table B.2 – Test plan for units for base load operation, level II . 39
Table B.3 − Test plan for other units without special requirements, level III . 40

IEC 60308:2024 © IEC 2024 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HYDRAULIC TURBINES –
TESTING OF GOVERNING 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
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 60308 has been prepared by IEC technical committee 4: Hydraulic turbines. It is an
International Standard.
This third edition cancels and replaces the second edition published in 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) adoption of parts of IEC 61362:2024 which deal with test matters;
b) introduction of new technical aspects;

– 6 – IEC 60308:2024 © IEC 2024
The text of this document is based on the following documents:
Draft Report on voting
4/497/FDIS 4/503/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

IEC 60308:2024 © IEC 2024 – 7 –
INTRODUCTION
The first and second editions of this document were developed to have a comprehensive
description for the test of hydraulic turbine governing systems according to the corresponding
state of the art. They were published independently of the guide to specification of hydraulic
turbine governing systems (IEC 61362). This third edition was developed together with
IEC 61362 in order to harmonize their contents and their publishing dates. Furthermore, the
standards are kept open for state of the art by introducing new topics and harmonizing the
structure as well as the terms and definitions for both standards.

– 8 – IEC 60308:2024 © IEC 2024
HYDRAULIC TURBINES –
TESTING OF GOVERNING SYSTEMS
1 Scope
This document covers acceptance tests and the related specific test procedures for hydraulic
turbine governing systems. It can be used to fulfil following tasks:
– verification of system characteristics according to specification;
– verification of technical guarantees;
– verification of general proper functioning in the workshop and/or on site;
– assessment of the actual state of an existing governing system.
This document covers the tests for systems and devices described in IEC 61362.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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, Field acceptance tests to determine the hydraulic performance of hydraulic turbines,
storage pumps and pump-turbines
IEC 60545, Guidelines for commissioning and operation of hydraulic turbines, pump-turbines
and storage pumps
IEC 61362, Guidelines to specification of hydraulic turbine governing systems
ISO 4406, Hydraulic fluid power − Fluids − Method for coding the level of contamination by solid
particles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61362 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp

IEC 60308:2024 © IEC 2024 – 9 –
4 Recommendations on tests
4.1 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). On site tests should be limited to the verification of such characteristics,
which:
– are indispensable for the safety, and
– cannot be carried out without the generating unit and the pressure supply system.
In 4.2 and 4.3, some basic aspects are summarised.
4.2 Recommendations on workshop tests
The scope of the tests, the best set up and the extent of the test documentation should be
stipulated in the contract in accordance with the requirements.
In case of type tests including EMC (electromagnetic compatibility), type tests already
performed by the manufacturer of the equipment or assembly, the corresponding certificates
shall be accepted in order to reduce the tests efforts to a reasonable level.
It should be early and clear enough stipulated, who will witness the tests.
For workshop tests, it is not necessary to set up all components of the governing system in a
complete loop, the electronic governor and the oil hydraulic governor can rather be tested
separately. During these independent tests, signals at interfaces between the electronic
governor and the oil hydraulic governor shall be clearly defined and measurable.Only if it is
explicitly required in the contract, the complete governing system, including the electronic and
the oil hydraulic governor should be assembled in the workshop. In this case the individual
testing of the systems is not needed.
In exceptional technically challenging situations, it can be an advantage to employ a plant
simulator for the workshop test of the digital governor (see also Clause 7). The use of a plant
simulator in the workshop test has to be clearly stipulated in the contract.
4.3 Recommendations on field tests
4.3.1 New governing systems
For governing systems, the following measures and steps apply.
– Safety devices, displays, alarms and trip settings shall be verified prior to conducting the
field tests.
– Commissioning of the complete generating unit shall be performed including load rejection
tests. The testing of governing systems shall be coordinated with the overall commissioning
of the hydro generating equipment; refer to IEC 60545.
For the actual governing system tests:
• The relevant control mode and operational mode to be checked is set, for example speed
control in island operation; subsequently defined test signals are superimposed and
resulting changes for the specified values through the entire operating range are observed
and/or recorded, whereby control settings can be optimized during the process. The results
of such tests can be used as baseline values in order to be compared with the results of
verification tests which are carried out during the lifetime of the equipment.

– 10 – IEC 60308:2024 © IEC 2024
• The test of the insensitivity of the governing system is only needed if the power station will
be participating in primary regulation of grid frequency, especially in peak load power
stations and in power stations with special requirements for high control accuracy (for
recommended insensitivities, see IEC 61362; acceptable measuring uncertainties are given
in Clause 6).
• In some cases, the parameters of the governing system can be determined based on
physical measurements. If the expected behaviour is not achieved and the reason for this
has to be identified, then other factors influencing the governing system behaviour shall be
examined. These factors can include: inertias, generator-load characteristics and the
influence of hydraulic forces on actuating times. The determination of the governing
system’s parameters and of the turbine transfer function can be used to provide models of
the power plant, in order to carry out studies of the power system’s dynamic behaviour.
• Special attention shall be given to the test of pump-turbines because of their complex turbine
characteristics (e.g. S-shape characteristic).
4.3.2 Existing governing systems
4.3.2.1 Motivation for a field test in an existing governing system
Existing governing systems can have deficiencies causing one or more of the following effects,
which can lead to the decision to conduct a field test:
– long settling times of the controlled variable;
– long synchronization times;
– drifting operating points;
– changes in actuator speeds;
– unusual oscillations (e.g. in no-load and/or island grid operation);
– excessive insensitivities and/or hysteresis effects;
– excessive leakages (long pumping periods, high oil temperature, etc.);
– general inconsistent governor performance.
4.3.2.2 Identification of deficiencies
Depending on the observed effects the following checks can be made:
– measurement of the insensitivity and dead time, see Clause A.1 and Clause A.2;
– recording of step responses/transient functions (unit step responses) by applying defined
signals at the input (command signal, controlled variable, frequency, etc.), for example see
Clause D.6 to Clause D.14;
– indexing the servomotors, see Clause A.3;
– checking the runner/guide vane relationship in Kaplan turbines, i. e. cam relation;
– checking the deflector/nozzle relationship in Pelton turbines;
– identifying possible resonances (with oscillations in the draft tube, surge tank, waterways:
penstock and/or channel system, the generator, the grid, etc.);
– measurements of the parameters of the governing system and comparison to the original
values recorded during the first commissioning, for example see Clause D.7 and
Clause D.8;
– checking of the overall functionality of the oil hydraulic system, for example see Clause A.4.

IEC 60308:2024 © IEC 2024 – 11 –
4.3.2.3 Deciding whether to replace or to repair existing governing systems
The above-mentioned checks give information about the possible causes of the deficiencies,
allowing to decide on the measures to be taken, such as for instance:
– overhauling of individual components;
– replacement of components or of complete governing systems;
– changes in the configuration.
Besides the above-mentioned points, the following facts can also influence the decision to
replace or repair existing elements or systems:
• the assessment of operating costs;
• the assessment of repair costs;
• the potential for operating and efficiency improvement of replacement versus repair;
• general safety and any other demands required by authorities.
5 Governing system tests
5.1 Test conditions to be fulfilled
5.1.1 General
The following test conditions apply, unless there is an explicit exception made in this document.
They can be modified by mutual agreement.
5.1.2 Turbine operation conditions
– Operating head on the turbine shall be within the limits specified in the turbine contract,
otherwise the method of correction should be agreed upon.
– Tailwater elevation and power output of the turbine shall be such that the net positive suction
head (NPSH), see IEC 60041, is not less than the lower limit of the turbine manufacturer’s
guarantee or recommendation.
– Steady-state power output of the turbine for constant position of the regulating devices (e.g.
wicket gate, runner, needle, deflector) shall not deviate from the specified value by more
than ±1,5 % of rated output.
5.1.3 Hydraulic pressure unit condition
Tests should be performed under approximately constant oil pressure. The fluctuations of the
supply oil pressure shall not exceed ±10 % of average oil pressure.
5.1.4 Deviation of values from specified operating conditions
5.1.4.1 General
It is important that specified values stated in the contract, upon which stated guarantees are
based, be adhered to as closely as possible. The relative deviations from specified values under
which it is permissible to make a governing system acceptance test are specified in 5.1.4.2 and
5.1.4.3.
5.1.4.2 Speed
If acceptance tests cannot be performed at the specified speed, the permissible deviation from
the specified speed and its effect on the acceptance test results shall be agreed upon prior to
tests.
– 12 – IEC 60308:2024 © IEC 2024
5.1.4.3 Oil hydraulic system
The acceptance tests of oil hydraulic systems pertain to the following parameters:
a) Pressure
Acceptance tests, performed on a governing system installed on site with the turbine running
or at standstill, shall be performed with the oil pressure as specified in the contract; for tests
performed in the workshop of the governing system manufacturer, because of the absence
of regulating force required by the turbine, the oil pressure of the last amplification stage of
the controller system can be reduced correspondingly after demonstrating satisfactory
operation at the specified pressure. This reduction in oil pressure shall be mutually agreed
upon prior to performing the tests.
b) Oil quality and temperature
Acceptance tests shall be performed with the oil quality specified in the contract. Otherwise
the oil quality should be agreed upon.
The prescriptions of the manufacturers of components regarding oil purity and absence of
foam in the oil shall be strictly observed.
Oil temperatures during the tests shall correspond to normal sustained operating conditions
and lie within the range indicated by the manufacturers of components.
5.1.5 Provisions for instruments
The final report shall state the manufacturer and manufacturer’s serial number of the
instruments and completely describe special devices or modifications to standard instruments
used in connection with the acceptance test.
5.1.6 Calibration of instruments
All instruments shall carry calibration certificates, valid on the date of the tests, issued by an
institution which is acceptable to both parties. The provision of calibration certificates shall be
the responsibility of the party providing the test instruments.
5.2 Electrical checks
5.2.1 General
Electronic systems like the digital governor 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;
– grounding;
– anti-static protection.
If certain basic safety measures are taken and guidelines adhered to, testing can concentrate
on checking the governing systems for proper functioning. Electrical checking is usually
performed in the form of type tests, because electrical checking is expensive and requires
qualified personnel as well as special testing equipment. For specifications of the
electromagnetic compatibility (EMC) tests refer to IEC 61362.

IEC 60308:2024 © IEC 2024 – 13 –
5.2.2 Selection of test location
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 governor is not located near the generating unit, provision for local emergency operation
of the governor should be made in the vicinity of the generating unit.
5.2.3 Power supply
The check of the power supply with a volt- and ampere meter, oscilloscope or transient recorder
should normally be carried out in the workshop and is generally limited to:
– tolerance limits and ripple factor;
– current input;
– if applicable, test of switch-over of redundant supply voltage;
– failure monitoring.
5.2.4 Overvoltage protection and suppression of interference voltage
The following can 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;
– grounding of inactive metal parts;
– protection of the peripheral devices against overvoltage by protective elements;
– wiring of inductive devices (relay coils, solenoid valves).
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.
5.3 Test of the process interface system
The electrical signals for actuator position, speed, power, flow, head (up-stream and tail race),
etc., shall be checked for:
– open circuit characteristic and hysteresis (actuator position);
– interference;
– filtering (power, flow, water level);
– limit value acquisition;
– fault monitoring, if available.
Signals communicated by bus systems shall also be checked for:
• proper transmission;
• network status.
– 14 – IEC 60308:2024 © IEC 2024
5.4 Test of converters, amplifiers and actuators
5.4.1 Electrohydraulic and electromechanical converters
5.4.1.1 General
The converters dealt with here are the connecting element between the electronic and the
hydraulic-mechanical part of the governing system, as described in IEC 61362. They are of
great importance for the overall behaviour of the governing system. Therefore, insensitivity,
precision (including temperature stability) and also the dynamic behaviour shall exceed the
corresponding properties of the subsequent amplifier stages.
5.4.1.2 Electrohydraulic converters
The most important characteristic is to establish the oil flow rate as a function of the electrical
command signal and of the pressure drop.

Figure 1 – Oil flow Q function of input current I and pressure drop ∆p
The curves of Figure 1 should be provided by the supplier of the electrohydraulic converter with
various pressure differences and, in addition, oil temperature and type of oil (viscosity grade)
should be indicated.
It is furthermore possible to check
– the dead time;
– the actuating forces as a function of the oil pressure;
– the dynamic characteristics.
If an emergency trip and failsafe (for example shutdown in the event of power failure) are
available, their function shall also be tested.
Generally, to achieve the specified performance, a vibration (dither) signal is applied, which
shall also be checked.
NOTE 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.
5.4.1.3 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)
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