IEC TS 62600-1:2011

Marine energy - Wave, tidal and other water current converters - Part 1: Terminology

IEC/TS 62600-1:2011(E) defines the terms relevant to ocean and marine renewable energy. For the purposes of this Technical Specification, sources of ocean and marine renewable energy are taken to include wave, tidal current, and other water current energy converters. This Technical Specification is intended to provide uniform terminology to facilitate communication between organizations and individuals in the marine renewable energy industry and those who interact with them.

General Information

• Status: Published
• Publication Date: 26-Mar-2019
• ICS: 27.140 - Hydraulic energy engineering
• Technical Committee: TC 114 - Marine energy - Wave, tidal and other water current converters
• Current Stage: DELPUB - Deleted Publication
• Start Date: 16-Jun-2020
• Completion Date: 31-Jan-2019

Relations

• Amended By: IEC TS 62600-1:2011/AMD1:2019 - Amendment 1 - Marine energy - Wave, tidal and other water current converters - Part 1: Terminology
• Effective Date: 05-Sep-2023
• Revised: IEC TS 62600-1:2020 - Marine energy - Wave, tidal and other water current converters - Part 1: Vocabulary
• Effective Date: 05-Sep-2023

Overview

IEC TS 62600-1:2011 - "Marine energy - Wave, tidal and other water current converters - Part 1: Terminology" is an IEC Technical Specification that establishes a common vocabulary for the marine renewable energy sector. It defines terms relevant to wave, tidal current and other water‑current energy converters to promote consistent communication among designers, researchers, regulators and industry stakeholders. The document is intended as a living glossary to support project development, modelling, testing and the creation of future standards.

Key Topics

This terminology TS covers core concepts and commonly used phrases in marine energy, including (but not limited to):

• Resource and performance terms: annual energy production, conversion efficiency (resource-to-wire), capture area (tidal), capture width/length (wave).
• Hydrodynamics and device motion: added mass, added mass at infinity, added mass coefficient, six degrees of freedom (heave, surge, sway, pitch, roll, yaw).
• Wave and current descriptions: energy period, directional wave spectrum, directional spreading function, directionally resolved power, current profile, deep water definition.
• Operational and asset terms: availability, array (marine energy), farm, amplitude control, extreme significant wave height, chart datum.
• Energy systems: energy storage capacity, excitation force (wave).

Definitions are harmonized with IEC 60050 (International Electrotechnical Vocabulary) and other IEC documents where applicable.

Applications

IEC TS 62600-1 is practical for:

• Device developers and marine engineers - to ensure consistent terms in design specifications, modelling reports and test plans.
• Resource analysts and ocean modellers - when describing wave spectra, directional spreading and current profiles for site assessment.
• Project developers and array designers - for communicating capture width/area, array spacing and expected annual energy production.
• Certification bodies and regulators - to align terminology used in permitting, compliance and performance claims.
• Researchers and educators - as a reference glossary when publishing papers or training materials.

Using standardized terminology reduces ambiguity in contracts, technical reports, resource characterizations and interdisciplinary collaboration across the marine renewable energy industry.

Related Standards (if applicable)

• IEC 60050 - International Electrotechnical Vocabulary (harmonization reference cited in the TS).
• Other parts of the IEC 62600 series (for device-specific requirements, testing and performance measurement) and standards developed by IEC Technical Committee 114 (Marine energy).

Keywords: IEC TS 62600-1:2011, marine energy terminology, wave energy, tidal current, marine renewable energy, WEC, TEC, capture width, conversion efficiency.

Standards Content (Sample)

IEC/TS 62600-1 ®
Edition 1.0 2011-12
TECHNICAL
SPECIFICATION
Marine energy – Wave, tidal and other water current converters –
Part 1: Terminology
IEC/TS 62600-1:2011(E)
All rights reserved. Unless otherwise specified, 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 either IEC or
IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: [e-mail]
Web: www.iec.ch
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
 Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
 IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
 Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
 Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: [e-mail]
Tel.: [phone]
Fax: [phone]
IEC/TS 62600-1 ®
Edition 1.0 2011-12
TECHNICAL
SPECIFICATION
Marine energy – Wave, tidal and other water current converters –
Part 1: Terminology
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 27.140 ISBN 978-2-88912-829-7

– 2 – TS 62600-1 © IEC:2011(E)
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Terms and definitions . 6
Bibliography . 26

Figure 1 – Six degrees of freedom – Floating device . 9
Figure 2 – Six degrees of freedom – Submerged device . 9
Figure 3 – Wave height and wave period . 23

TS 62600-1 © IEC:2011(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 1: Terminology
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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.
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC 62600-1, which is a technical specification, has been prepared by IEC technical
committee 114: Marine energy – Wave, tidal and other water current converters.

– 4 – TS 62600-1 © IEC:2011(E)
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
114/65/DTS 114/76/RVC
Full information on the voting for the approval of this technical specification 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 stability 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
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

TS 62600-1 © IEC:2011(E) – 5 –
INTRODUCTION
This Technical Specification has been developed as a tool for the international marine energy
community, to assist in creating clarity and understanding. The wave, tidal and water current
energy industry has recently experienced a period of rapid growth and sector development.
With this expansion, it became apparent that a glossary of terms for the sector was required.
The aim of this Technical Specification is to present clear and consistent language that will
aid the development of programs, projects, and future standards.
This Technical Specification lists the terms that the marine energy industry commonly uses. It
is an evolving document that will change as new terms and symbols are added. The
terminologies herein have been harmonized with IEC 60050 and other IEC documents as far
as possible.
– 6 – TS 62600-1 © IEC:2011(E)
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 1: Terminology
1 Scope
This part of IEC 62600 defines the terms relevant to ocean and marine renewable energy. For
the purposes of this Technical Specification, sources of ocean and marine renewable energy
are taken to include wave, tidal current, and other water current energy converters.
Terms relating to conventional dam and tidal barrage, offshore wind, marine biomass, ocean
thermal and salinity gradient energy conversion are not included in the scope of this Technical
Specification.
This Technical Specification is intended to provide uniform terminology to facilitate
communication between organizations and individuals in the marine renewable energy
industry and those who interact with them.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
added mass
extra mass associated with the additional force necessary to accelerate a body through a fluid
compared to the same acceleration in a vacuum
NOTE 1 In general, added mass is a variable that depends on the state of the unsteady motion and is not a
constant.
NOTE 2 In a viscous (real) fluid, the added mass would include kinetic energy of a fluid layer entrained by the
accelerating body.
2.2
added mass at infinity
limit of the mass corresponding to the added mass as the frequency tends to infinity
NOTE The value of added mass at infinity is normally necessary for time domain modelling of wave-body
interaction.
2.3
added mass coefficient
ratio between added mass and the mass of the water displaced by the submerged body
2.4
amplitude control
method to obtain the optimum oscillatory motion amplitude to capture a maximum of wave
energy
NOTE For a simple oscillating system, the object of amplitude control is to obtain a given oscillatory velocity
amplitude that should be related with the wave excitation force.

TS 62600-1 © IEC:2011(E) – 7 –
2.5
annual energy production (marine energy converter)
estimate of total energy production of a marine energy converter system during a one-year
period obtained by applying its power performance assessment to a prospective marine
energy resource characterization and assuming 100 % availability
NOTE Actual annual energy production is unlikely to exceed this estimate.
[IEC 60050-415:1999, 415-05-09, modified]
2.6
array (marine energy)
farm of marine energy converters arranged specifically so as to enhance energy capture
NOTE Array spacing is dictated by hydrodynamic considerations and may be very closely packed so as to
constitute a single platform or an arrangement of identical devices.
2.7
attenuator device
energy converter which is aligned parallel to the predominant direction of wave incidence
2.8
availability (marine energy converter)
ability of a marine energy conversion system to be in a state to perform a necessary function
under given conditions at a given instant of time or over a given duration, assuming that the
necessary external resources are provided
NOTE 1 For continuously running equipment availability equates to: uptime/(uptime + downtime).
NOTE 2 Where reliability is specified in Mean Time Between Failures (MTBF) and maintainability in Mean Time
To Repair (MTTR), availability also equates to: MTBF/(MTBF + MTTR).
[IEC 60050-191:1990, 191-02-05, modified]
2.9
capture area (tidal)
equal to the power captured by the hydrodynamically functional part of a TEC divided by
power per square metre of the incident tidal stream
2.10
capture length (wave)
capture width
equal to the power captured by the hydrodynamically functional part of a WEC divided by
power per metre of the incident wave field
2.11
centre of buoyancy
centroid of the submerged volume
2.12
centre of flotation
point coinciding with the centroid of the water-plane area
NOTE The water-plane area is the cross-sectional area of the floating body at mean water level in calm water.
2.13
chart datum
reference level of water, typically from a selected phase of the tide at a specific location
NOTE Different hydrographic organizations have differing conventions for defining chart datum.

– 8 – TS 62600-1 © IEC:2011(E)
2.14
conversion efficiency (resource to wire)
measure of the overall effectiveness of a marine energy converter calculated as the ratio of
electrical power output in relation to the incident power in the water resource
NOTE 1 For WECs, conversion efficiency (resource to wire) is sometimes referred to as wave-to-wire conversion
efficiency.
NOTE 2 Conversion efficiency (resource to wire) is normally calculated over extended periods (e.g. tidal cycle,
years, etc.).
2.15
current profile
variation in velocity throughout the water column, typically displayed as a function of height
above the sea bed
2.16
deep water (offshore)
spatial location where the depth of the water is greater than or equal to half the wave length
NOTE The deep water (offshore) spatial location is based on the kinematic properties of waves. The dispersion
equation is
gT 2πd
L = tanh
2π L
where
L is the wave length;
d is the water depth;
T is the period;
g is the gravitation acceleration.
In deep water, the dispersion equation may be simplified to
gT
L = = 1,56T
2π
2.17
degree of freedom
independent displacements and/or rotations that specify the orientation of a body or system
NOTE 1 A marine body may experience three linear and three rotational motions as depicted in Figures 1 and 2.
NOTE 2 The principal axis is parallel to the mean water surface and aligned with the direction of incident energy,
and the rotations act about the centre of gravity.

TS 62600-1 © IEC:2011(E) – 9 –
+A
+B
+E +C
H
A
+D +F
E
C
F
D
G
IEC  2653/11
B
Key
A Heave D Surge G Centre of gravity
B Yaw E Roll H Incident energy
C Pitch F Sway
Figure 1 – Six degrees of freedom – Floating device

A
H
+A
E
C
+B
G
+E +C
+D +F D
F
B
I
IEC  2654/11
Key
A Heave D Surge G Centre of gravity
B Yaw E Roll H Incident energy
C Pitch F Sway I Seabed
Figure 2 – Six degrees of freedom – Submerged device

– 10 – TS 62600-1 © IEC:2011(E)
2.17.1
heave
motion in a direction perpendicular to the mean water surface
2.17.2
pitch
rotation about the sway axis
2.17.3
roll
rotation about the surge axis
2.17.4
surge
motion parallel to the principal axis
2.17.5
sway
motion perpendicular to the principal axis and parallel to the mean water surface
2.17.6
yaw
rotation about the heave axis
2.18
directionally resolved power (wave)
distribution of wave power in a given sea state as a function of the angle of incidence
2.19
directional spreading function
normalized distribution of wave energy, D, for a given frequency, f, over the angle of
incidence, θ
2π
NOTE Since D(θ, f )dθ =1 it may be considered to be a probability density function over direction.
∫
2.20
directional wave spectrum
distribution of the spectral density as a function of incident wave frequency and direction

NOTE The directional wave spectrum is calculated as the product of the spectral density, as a function of incident
wave frequency, multiplied with the directional spreading function.
2.21
diurnal tides
occurrence of only one high water and one low water in each tidal day
NOTE A tidal day is equal to 24,8 h.
2.22
energy period (wave)
T
e
characteristic wave period associated with energy propagation expressed as the group
velocity weighted mean period of the frequency spectrum
NOTE 1 A monochromatic wave in deep water, whose variance and period match the variance and energy period
of a specified polychromatic sea state, will also have the same wave power.

TS 62600-1 © IEC:2011(E) – 11 –
NOTE 2 In accordance with IAHR, the spectral estimate of the energy period is preferred.
m
−1
, where m and m are the minus-one and zero spectral moments.
T =
–1 0
e
m
2.23
energy storage capacity
measure of the amount of energy a storage device can store and deliver, within established
design limits and maintenance interval conditions
NOTE The energy storage capacity is specified in terms of energy units such as kJ, MJ, kWh or MWh (i.e. the
kinetic energy stored in a flywheel, the hydraulic energy stored in accumulators or potential energy stored in a
water reservoir).
2.24
excitation force (wave)
force which an incident wave exerts on a static body
2.25
extreme significant wave height
significant wave height (H ) of the most severe sea state expected at a site over a specific
m0
return period or design life
NOTE This definition provides for extreme wave heights to be defined in terms of a 50/100 year storm condition.
2.26
farm
group of similar marine energy converters of the same type (either WECs or TECs) sharing a
connection to the electric grid
NOTE Farm spacing will normally be dictated by installation, mooring and access requirements.
2.27
fast tuning
adaptive control of a device over a typical wave period
NOTE Adaptive tuning, real-time control, or complex conjugate control is examples of fast tuning.
2.28
fetch
unobstructed distance of water surface over which the wind has acted
2.29
focusing absorber device
energy converter that uses a method to concentrate waves onto a central converter to
enhance energy production
2.30
free surface
interface between the air and a body of water
2.31
group velocity (wave)
propagation velocity of water wave groups and the wave energy
NOTE The group velocity of a water wave is the velocity that the energy associated with the wave disturbance
travels in the direction of wave propagation. In deep water using linear wave theory this is one half the wave phase
velocity. In shallow water it is equal to the wave phase velocity.

– 12 – TS 62600-1 © IEC:2011(E)
2.32
harmonic analysis of tides
representation of tidal elevations and velocities by the summation of components whose
amplitudes and periods describe astronomical processes
2.33
highest astronomical tide
HAT
highest sea level due to an astronomical tide that can be expected to occur under average
meteorological conditions and under any combination of astronomical conditions
NOTE The highest astronomical tide is not an extreme sea level, as certain meteorological conditions can cause a
higher sea level. The sea level under these circumstances is known as a storm surge. HAT is determined by
inspecting predicted sea levels over a number of years.
[National Oceanography Centre – Natural Environment Resource Council (NERC), 2011]
2.34
in-stream generation
capture and conversion of the energy of flowing water
NOTE In-stream generation includes tidal, ocean current, and flowing river environments.
2.35
intermediate depth water
spatial location where the kinematics properties of the waves are such that the water depth is
less than half the wave length but equal to or greater than a twentieth of the wave length
NOTE In intermediate water, the dispersion equation is
gT 2πd
, where L = wave length, d = water depth, T = period and g = gravitation acceleration
L = tanh
2π L
2.36
latching
restraining the motion of the primary interface at the extremes of its range of motion to
improve power capture
NOTE Latching is sometimes referred to as phase control because latching is often used to align the excitation
(force or pressure) and response (velocity or flow rate), and this can be understood as reducing the phase
difference between the principal frequency components of these parameters.
2.37
lowest astronomical tide
LAT
lowest sea level due to an astronomical tide that can be expected to occur under average
meteorological conditions and under any combination of astronomical conditions
NOTE The lowest astronomical tide is not an extreme sea level, as certain meteorological conditions can cause a
lower sea level. The sea level under these circumstances is known as a negative surge. LAT is determined by
inspecting predicted sea levels over a number of years. LAT is commonly used as the datum point from which sea
level is measured.
[National Oceanography Centre – NERC, 2011]
2.38
maintainability
probability that a given active maintenance action, for an item under given conditions of use,
can be carried out within a given duration, when the maintenance is performed under stated
conditions and using stated procedures and resources
[IEC 60050-191:1990, 191-13-01, modified]

TS 62600-1 © IEC:2011(E) – 13 –
2.39
marine current
persistent flow of seawater produced by natural physical processes, including the gravitational
pull of celestial bodies
2.40
maximum average power
time-averaged power produced by a device under peak operating conditions over a given
interval
NOTE 1 For a wave device, peak operating conditions represent the maximum operating sea conditions.
NOTE 2 For a tidal device, peak operating conditions would be the maximum flow rates.
2.41
maximum individual wave height
H
max
statistical measure of the largest individual wave heights which can be observed or expected
in a given sea state for a stated probability of exceedance
NOTE Maximum individual wave height is normally calculated from a Rayleigh distribution for wave heights in
deep water for an exceedance probability of one per thousand, for which a H = 1,86 H .
max m0
2.42
mean annual wave power
long-term average of the directionally unresolved wave energy flux per unit width, calculated
as an arithmetic mean over all sea states occurring at a given location
NOTE Typically mean annual wave power units are expressed in kilowatts per metre.
2.43
mean high water neaps
MHWN
annual average height (when the average maximum declination of the moon is 23,5 degrees)
of two successive high waters during those time intervals of 24 h when the range of the
astronomical tide is at its least
NOTE The values of mean high water neaps vary from year to year with a cycle of approximately 18,6 years.
[National Oceanography Centre – NERC, 2011, modified]
2.44
mean high water springs
MHWS
annual average height (when the average maximum declination of the moon is 23,5 degrees)
of two successive high waters during those time intervals of 24 h when the range of the
astronomical tide is at its greatest
NOTE Th
...

IEC/TS 62600-1 ®
Edition 1.0 2011-12
TECHNICAL
SPECIFICATION
Marine energy – Wave, tidal and other water current converters –
Part 1: Terminology
IEC/TS 62600-1:2011(E)
All rights reserved. Unless otherwise specified, 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 either IEC or

IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.

Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette

publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: [e-mail]
Web: www.iec.ch
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
 Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
 IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
 Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
 Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: [e-mail]
Tel.: [phone]
Fax: [phone]
IEC/TS 62600-1 ®
Edition 1.0 2011-12
TECHNICAL
SPECIFICATION
Marine energy – Wave, tidal and other water current converters –
Part 1: Terminology
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 27.140 ISBN 978-2-88912-829-7

– 2 – TS 62600-1 © IEC:2011(E)

CONTENTS
FOREWORD . 3

INTRODUCTION . 5

1 Scope . 6

2 Terms and definitions . 6

Bibliography . 26

Figure 1 – Six degrees of freedom – Floating device . 9

Figure 2 – Six degrees of freedom – Submerged device . 9
Figure 3 – Wave height and wave period . 23

TS 62600-1 © IEC:2011(E) – 3 –

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 1: Terminology
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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.

The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC 62600-1, which is a technical specification, has been prepared by IEC technical
committee 114: Marine energy – Wave, tidal and other water current converters.

– 4 – TS 62600-1 © IEC:2011(E)

The text of this technical specification is based on the following documents:

Enquiry draft Report on voting

114/65/DTS 114/76/RVC
Full information on the voting for the approval of this technical specification 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 stability 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
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

TS 62600-1 © IEC:2011(E) – 5 –

INTRODUCTION
This Technical Specification has been developed as a tool for the international marine energy

community, to assist in creating clarity and understanding. The wave, tidal and water current

energy industry has recently experienced a period of rapid growth and sector development.

With this expansion, it became apparent that a glossary of terms for the sector was required.

The aim of this Technical Specification is to present clear and consistent language that will

aid the development of programs, projects, and future standards.

This Technical Specification lists the terms that the marine energy industry commonly uses. It

is an evolving document that will change as new terms and symbols are added. The

terminologies herein have been harmonized with IEC 60050 and other IEC documents as far
as possible.
– 6 – TS 62600-1 © IEC:2011(E)

MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 1: Terminology
1 Scope
This part of IEC 62600 defines the terms relevant to ocean and marine renewable energy. For
the purposes of this Technical Specification, sources of ocean and marine renewable energy
are taken to include wave, tidal current, and other water current energy converters.
Terms relating to conventional dam and tidal barrage, offshore wind, marine biomass, ocean
thermal and salinity gradient energy conversion are not included in the scope of this Technical
Specification.
This Technical Specification is intended to provide uniform terminology to facilitate
communication between organizations and individuals in the marine renewable energy
industry and those who interact with them.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
added mass
extra mass associated with the additional force necessary to accelerate a body through a fluid
compared to the same acceleration in a vacuum
NOTE 1 In general, added mass is a variable that depends on the state of the unsteady motion and is not a
constant.
NOTE 2 In a viscous (real) fluid, the added mass would include kinetic energy of a fluid layer entrained by the
accelerating body.
2.2
added mass at infinity
limit of the mass corresponding to the added mass as the frequency tends to infinity

NOTE The value of added mass at infinity is normally necessary for time domain modelling of wave-body
interaction.
2.3
added mass coefficient
ratio between added mass and the mass of the water displaced by the submerged body
2.4
amplitude control
method to obtain the optimum oscillatory motion amplitude to capture a maximum of wave
energy
NOTE For a simple oscillating system, the object of amplitude control is to obtain a given oscillatory velocity
amplitude that should be related with the wave excitation force.

TS 62600-1 © IEC:2011(E) – 7 –

2.5
annual energy production (marine energy converter)

estimate of total energy production of a marine energy converter system during a one-year

period obtained by applying its power performance assessment to a prospective marine

energy resource characterization and assuming 100 % availability

NOTE Actual annual energy production is unlikely to exceed this estimate.

[IEC 60050-415:1999, 415-05-09, modified]

2.6
array (marine energy)
farm of marine energy converters arranged specifically so as to enhance energy capture
NOTE Array spacing is dictated by hydrodynamic considerations and may be very closely packed so as to
constitute a single platform or an arrangement of identical devices.
2.7
attenuator device
energy converter which is aligned parallel to the predominant direction of wave incidence
2.8
availability (marine energy converter)
ability of a marine energy conversion system to be in a state to perform a necessary function
under given conditions at a given instant of time or over a given duration, assuming that the
necessary external resources are provided
NOTE 1 For continuously running equipment availability equates to: uptime/(uptime + downtime).
NOTE 2 Where reliability is specified in Mean Time Between Failures (MTBF) and maintainability in Mean Time
To Repair (MTTR), availability also equates to: MTBF/(MTBF + MTTR).
[IEC 60050-191:1990, 191-02-05, modified]
2.9
capture area (tidal)
equal to the power captured by the hydrodynamically functional part of a TEC divided by
power per square metre of the incident tidal stream
2.10
capture length (wave)
capture width
equal to the power captured by the hydrodynamically functional part of a WEC divided by
power per metre of the incident wave field

2.11
centre of buoyancy
centroid of the submerged volume
2.12
centre of flotation
point coinciding with the centroid of the water-plane area
NOTE The water-plane area is the cross-sectional area of the floating body at mean water level in calm water.
2.13
chart datum
reference level of water, typically from a selected phase of the tide at a specific location
NOTE Different hydrographic organizations have differing conventions for defining chart datum.

– 8 – TS 62600-1 © IEC:2011(E)

2.14
conversion efficiency (resource to wire)

measure of the overall effectiveness of a marine energy converter calculated as the ratio of

electrical power output in relation to the incident power in the water resource

NOTE 1 For WECs, conversion efficiency (resource to wire) is sometimes referred to as wave-to-wire conversion
efficiency.
NOTE 2 Conversion efficiency (resource to wire) is normally calculated over extended periods (e.g. tidal cycle,

years, etc.).
2.15
current profile
variation in velocity throughout the water column, typically displayed as a function of height
above the sea bed
2.16
deep water (offshore)
spatial location where the depth of the water is greater than or equal to half the wave length
NOTE The deep water (offshore) spatial location is based on the kinematic properties of waves. The dispersion
equation is
gT 2πd
L = tanh
2π L
where
L is the wave length;
d is the water depth;
T is the period;
g is the gravitation acceleration.
In deep water, the dispersion equation may be simplified to
gT
L = = 1,56T
2π
2.17
degree of freedom
independent displacements and/or rotations that specify the orientation of a body or system
NOTE 1 A marine body may experience three linear and three rotational motions as depicted in Figures 1 and 2.
NOTE 2 The principal axis is parallel to the mean water surface and aligned with the direction of incident energy,

and the rotations act about the centre of gravity.

TS 62600-1 © IEC:2011(E) – 9 –

+A
+B
+E +C
H
A
+D +F
E
C
F
D
G
IEC  2653/11
B
Key
A Heave D Surge G Centre of gravity
B Yaw E Roll H Incident energy
C Pitch F Sway
Figure 1 – Six degrees of freedom – Floating device

A
H
+A
E
C
+B
G
+E +C
+D +F D
F
B
I
IEC  2654/11
Key
A Heave D Surge G Centre of gravity
B Yaw E Roll H Incident energy
C Pitch F Sway I Seabed
Figure 2 – Six degrees of freedom – Submerged device

– 10 – TS 62600-1 © IEC:2011(E)

2.17.1
heave
motion in a direction perpendicular to the mean water surface

2.17.2
pitch
rotation about the sway axis
2.17.3
roll
rotation about the surge axis
2.17.4
surge
motion parallel to the principal axis
2.17.5
sway
motion perpendicular to the principal axis and parallel to the mean water surface
2.17.6
yaw
rotation about the heave axis
2.18
directionally resolved power (wave)
distribution of wave power in a given sea state as a function of the angle of incidence
2.19
directional spreading function
normalized distribution of wave energy, D, for a given frequency, f, over the angle of
incidence, θ
2π
NOTE Since D(θ, f )dθ =1 it may be considered to be a probability density function over direction.
∫
2.20
directional wave spectrum
distribution of the spectral density as a function of incident wave frequency and direction

NOTE The directional wave spectrum is calculated as the product of the spectral density, as a function of incident
wave frequency, multiplied with the directional spreading function.
2.21
diurnal tides
occurrence of only one high water and one low water in each tidal day
NOTE A tidal day is equal to 24,8 h.
2.22
energy period (wave)
T
e
characteristic wave period associated with energy propagation expressed as the group
velocity weighted mean period of the frequency spectrum
NOTE 1 A monochromatic wave in deep water, whose variance and period match the variance and energy period
of a specified polychromatic sea state, will also have the same wave power.

TS 62600-1 © IEC:2011(E) – 11 –

NOTE 2 In accordance with IAHR, the spectral estimate of the energy period is preferred.

m
−1
, where m and m are the minus-one and zero spectral moments.
T =
–1 0
e
m
2.23
energy storage capacity
measure of the amount of energy a storage device can store and deliver, within established
design limits and maintenance interval conditions

NOTE The energy storage capacity is specified in terms of energy units such as kJ, MJ, kWh or MWh (i.e. the

kinetic energy stored in a flywheel, the hydraulic energy stored in accumulators or potential energy stored in a

water reservoir).
2.24
excitation force (wave)
force which an incident wave exerts on a static body
2.25
extreme significant wave height
significant wave height (H ) of the most severe sea state expected at a site over a specific
m0
return period or design life
NOTE This definition provides for extreme wave heights to be defined in terms of a 50/100 year storm condition.
2.26
farm
group of similar marine energy converters of the same type (either WECs or TECs) sharing a
connection to the electric grid
NOTE Farm spacing will normally be dictated by installation, mooring and access requirements.
2.27
fast tuning
adaptive control of a device over a typical wave period
NOTE Adaptive tuning, real-time control, or complex conjugate control is examples of fast tuning.
2.28
fetch
unobstructed distance of water surface over which the wind has acted
2.29
focusing absorber device
energy converter that uses a method to concentrate waves onto a central converter to
enhance energy production
2.30
free surface
interface between the air and a body of water
2.31
group velocity (wave)
propagation velocity of water wave groups and the wave energy
NOTE The group velocity of a water wave is the velocity that the energy associated with the wave disturbance
travels in the direction of wave propagation. In deep water using linear wave theory this is one half the wave phase
velocity. In shallow water it is equal to the wave phase velocity.

– 12 – TS 62600-1 © IEC:2011(E)

2.32
harmonic analysis of tides
representation of tidal elevations and velocities by the summation of components whose

amplitudes and periods describe astronomical processes

2.33
highest astronomical tide
HAT
highest sea level due to an astronomical tide that can be expected to occur under average

meteorological conditions and under any combination of astronomical conditions

NOTE The highest astronomical tide is not an extreme sea level, as certain meteorological conditions can cause a
higher sea level. The sea level under these circumstances is known as a storm surge. HAT is determined by
inspecting predicted sea levels over a number of years.
[National Oceanography Centre – Natural Environment Resource Council (NERC), 2011]
2.34
in-stream generation
capture and conversion of the energy of flowing water
NOTE In-stream generation includes tidal, ocean current, and flowing river environments.
2.35
intermediate depth water
spatial location where the kinematics properties of the waves are such that the water depth is
less than half the wave length but equal to or greater than a twentieth of the wave length
NOTE In intermediate water, the dispersion equation is
gT 2πd
, where L = wave length, d = water depth, T = period and g = gravitation acceleration
L = tanh
2π L
2.36
latching
restraining the motion of the primary interface at the extremes of its range of motion to
improve power capture
NOTE Latching is sometimes referred to as phase control because latching is often used to align the excitation
(force or pressure) and response (velocity or flow rate), and this can be understood as reducing the phase
difference between the principal frequency components of these parameters.
2.37
lowest astronomical tide
LAT
lowest sea level due to an astronomical tide that can be expected to occur under average
meteorological conditions and under any combination of astronomical conditions
NOTE The lowest astronomical tide is not an extreme sea level, as certain meteorological conditions can cause a
lower sea level. The sea level under these circumstances is known as a negative surge. LAT is determined by
inspecting predicted sea levels over a number of years. LAT is commonly used as the datum point from which sea
level is measured.
[National Oceanography Centre – NERC, 2011]
2.38
maintainability
probability that a given active maintenance action, for an item under given conditions of use,
can be carried out within a given duration, when the maintenance is performed under stated
conditions and using stated procedures and resources
[IEC 60050-191:1990, 191-13-01, modified]

TS 62600-1 © IEC:2011(E) – 13 –

2.39
marine current
persistent flow of seawater produced by natural physical processes, including the gravitational

pull of celestial bodies
2.40
maximum average power
time-averaged power produced by a device under peak operating conditions over a given

interval
NOTE 1 For a wave device, peak operating conditions represent the maximum operating sea conditions.

NOTE 2 For a tidal device, peak operating conditions would be the maximum flow rates.
2.41
maximum individual wave height
H
max
statistical measure of the largest individual wave heights which can be observed or expected
in a given sea state for a stated probability of exceedance
NOTE Maximum individual wave height is normally calculated from a Rayleigh distribution for wave heights in
deep water for an exceedance probability of one per thousand, for which a H = 1,86 H .
max m0
2.42
mean annual wave power
long-term average of the directionally unresolved wave energy flux per unit width, calculated
as an arithmetic mean over all sea states occurring at a given location
NOTE Typically mean annual wave power units are expressed in kilowatts per metre.
2.43
mean high water neaps
MHWN
annual average height (when the average maximum declination of the moon is 23,5 degrees)
of two successive high waters during those time intervals of 24 h when the range of the
astronomical tide is at its least
NOTE The values of mean high water neaps vary from year to year with a cycle of approximately 18,6 years.
[National Oceanography Centre – NERC, 2011, modified]
2.44
mean high water springs
MHWS
annual average height (when the average maximum declination of the moon is 23,5 degrees)
of two successive high waters during those time intervals of 24 h when the range of the
astronomical tide is at i
...

IEC TS 62600-1 ®
Edition 1.1 2019-03
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Marine energy – Wave, tidal and other water current converters –
Part 1: Terminology
All rights reserved. Unless otherwise specified, 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
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.

need further assistance, please contact the Customer Service

Centre: [e-mail].
IEC TS 62600-1 ®
Edition 1.1 2019-03
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Marine energy – Wave, tidal and other water current converters –
Part 1: Terminology
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.140 ISBN 978-2-8322-6740-0

IEC TS 62600-1 ®
Edition 1.1 2019-03
CONSOLIDATED VERSION
REDLINE VERSION
colour
inside
Marine energy – Wave, tidal and other water current converters –
Part 1: Terminology
– 2 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Terms and definitions . 6
Bibliography . 27
Figure 1 – Six degrees of freedom – Floating device . 9
Figure 2 – Six degrees of freedom – Submerged device . 9
Figure 3 – Wave height and wave period . 23

© IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –
Part 1: Terminology
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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.
This consolidated version of the official IEC Standard and its amendment has been
prepared for user convenience.
IEC TS 62600-1 edition 1.1 contains the first edition (2011-12) [documents 114/65/DTS
and 114/76/RVC] and its amendment 1 (2019-03) [documents 114/289/DTS and 114/302/
RVDTS].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendment 1. Additions are in green text, deletions are in strikethrough
red text. A separate Final version with all changes accepted is available in this
publication.
– 4 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC 62600-1, which is a technical specification, has been prepared by IEC technical
committee 114: Marine energy – Wave, tidal and other water current converters.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication and its amendment will
remain unchanged until the stability 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
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.

© IEC 2019
INTRODUCTION
This Technical Specification has been developed as a tool for the international marine energy
community, to assist in creating clarity and understanding. The wave, tidal and water current
energy industry has recently experienced a period of rapid growth and sector development.
With this expansion, it became apparent that a glossary of terms for the sector was required.
The aim of this Technical Specification is to present clear and consistent language that will
aid the development of programs, projects, and future standards.
This Technical Specification lists the terms that the marine energy industry commonly uses. It
is an evolving document that will change as new terms and symbols are added. The
terminologies herein have been harmonized with IEC 60050 and other IEC documents as far
as possible.
– 6 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 1: Terminology
1 Scope
This part of IEC 62600 defines the terms relevant to ocean and marine renewable energy. For
the purposes of this Technical Specification, sources of ocean and marine renewable energy
are taken to include wave, tidal current, and other water current energy converters.
Terms relating to conventional dam and tidal barrage, offshore wind, marine biomass, ocean
thermal and salinity gradient energy conversion are not included in the scope of this Technical
Specification.
This Technical Specification is intended to provide uniform terminology to facilitate
communication between organizations and individuals in the marine renewable energy
industry and those who interact with them.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
added mass
extra mass associated with the additional force necessary to accelerate a body through a fluid
compared to the same acceleration in a vacuum
NOTE 1 In general, added mass is a variable that depends on the state of the unsteady motion and is not a
constant.
NOTE 2 In a viscous (real) fluid, the added mass would include kinetic energy of a fluid layer entrained by the
accelerating body.
2.2
added mass at infinity
limit of the mass corresponding to the added mass as the frequency tends to infinity
NOTE The value of added mass at infinity is normally necessary for time domain modelling of wave-body
interaction.
2.3
added mass coefficient
ratio between added mass and the mass of the water displaced by the submerged body
2.4
amplitude control
method to obtain the optimum oscillatory motion amplitude to capture a maximum of wave
energy
NOTE For a simple oscillating system, the object of amplitude control is to obtain a given oscillatory velocity
amplitude that should be related with the wave excitation force.

© IEC 2019
2.5
annual energy production (marine energy converter)
estimate of total energy production of a marine energy converter system during a one-year
period obtained by applying its power performance assessment to a prospective marine
energy resource characterization and assuming 100 % availability
NOTE Actual annual energy production is unlikely to exceed this estimate.
[IEC 60050-415:1999, 415-05-09, modified]
2.6
array (marine energy)
farm of marine energy converters arranged specifically so as to enhance energy capture
NOTE Array spacing is dictated by hydrodynamic considerations and may be very closely packed so as to
constitute a single platform or an arrangement of identical devices.
2.7
attenuator device
energy converter which is aligned parallel to the predominant direction of wave incidence
2.8
availability (marine energy converter)
ability of a marine energy conversion system to be in a state to perform a necessary function
under given conditions at a given instant of time or over a given duration, assuming that the
necessary external resources are provided
NOTE 1 For continuously running equipment availability equates to: uptime/(uptime + downtime).
NOTE 2 Where reliability is specified in Mean Time Between Failures (MTBF) and maintainability in Mean Time
To Repair (MTTR), availability also equates to: MTBF/(MTBF + MTTR).
[IEC 60050-191:1990, 191-02-05, modified]
2.9
capture area (tidal)
equal to the power captured by the hydrodynamically functional part of a TEC divided by
power per square metre of the incident tidal stream
2.10
capture length (wave)
capture width
equal to the power captured by the hydrodynamically functional part of a WEC divided by
power per metre of the incident wave field
2.11
centre of buoyancy
centroid of the submerged volume
2.12
centre of flotation
point coinciding with the centroid of the water-plane area
NOTE The water-plane area is the cross-sectional area of the floating body at mean water level in calm water.
2.13
chart datum
reference level of water, typically from a selected phase of the tide at a specific location
NOTE Different hydrographic organizations have differing conventions for defining chart datum.

– 8 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
2.14
conversion efficiency (resource to wire)
measure of the overall effectiveness of a marine energy converter calculated as the ratio of
electrical power output in relation to the incident power in the water resource
NOTE 1 For WECs, conversion efficiency (resource to wire) is sometimes referred to as wave-to-wire conversion
efficiency.
NOTE 2 Conversion efficiency (resource to wire) is normally calculated over extended periods (e.g. tidal cycle,
years, etc.).
2.15
current profile
variation in velocity throughout the water column, typically displayed as a function of height
above the sea bed
2.16
deep water (offshore)
spatial location where the depth of the water is greater than or equal to half the wave length
NOTE The deep water (offshore) spatial location is based on the kinematic properties of waves. The dispersion
equation is
gT 2πd
L = tanh
2π L
where
L is the wave length;
d is the water depth;
T is the period;
g is the gravitation acceleration.
In deep water, the dispersion equation may be simplified to
gT
L = = 1,56T
2π
2.17
degree of freedom
independent displacements and/or rotations that specify the orientation of a body or system
NOTE 1 A marine body may experience three linear and three rotational motions as depicted in Figures 1 and 2.
NOTE 2 The principal axis is parallel to the mean water surface and aligned with the direction of incident energy,
and the rotations act about the centre of gravity.

© IEC 2019
+A
+B
+E +C
H
A
+D +F
E
C
F
D
G
IEC  2653/11
B
Key
A Heave D Surge G Centre of gravity
B Yaw E Roll H Incident energy
C Pitch F Sway
Figure 1 – Six degrees of freedom – Floating device

A
H
+A
E
C
+B
G
+E +C
+D +F D
F
B
I
IEC  2654/11
Key
A Heave D Surge G Centre of gravity
B Yaw E Roll H Incident energy
C Pitch F Sway I Seabed
Figure 2 – Six degrees of freedom – Submerged device

– 10 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
2.17.1
heave
motion in a direction perpendicular to the mean water surface
2.17.2
pitch
rotation about the sway axis
2.17.3
roll
rotation about the surge axis
2.17.4
surge
motion parallel to the principal axis
2.17.5
sway
motion perpendicular to the principal axis and parallel to the mean water surface
2.17.6
yaw
rotation about the heave axis
2.18
directionally resolved power (wave)
distribution of wave power in a given sea state as a function of the angle of incidence
2.19
directional spreading function
normalized distribution of wave energy, D, for a given frequency, f, over the angle of
incidence, θ
2π
NOTE Since D(θ, f )dθ =1 it may be considered to be a probability density function over direction.
∫
2.20
directional wave spectrum
distribution of the spectral density as a function of incident wave frequency and direction

NOTE The directional wave spectrum is calculated as the product of the spectral density, as a function of incident
wave frequency, multiplied with the directional spreading function.
2.21
diurnal tides
occurrence of only one high water and one low water in each tidal day
NOTE A tidal day is equal to 24,8 h.
2.22
energy period (wave)
T
e
characteristic wave period associated with energy propagation expressed as the group
velocity weighted mean period of the frequency spectrum
NOTE 1 A monochromatic wave in deep water, whose variance and period match the variance and energy period
of a specified polychromatic sea state, will also have the same wave power.

© IEC 2019
NOTE 2 In accordance with IAHR, the spectral estimate of the energy period is preferred.
m
−1
, where m and m are the minus-one and zero spectral moments.
T =
–1 0
e
m
2.23
energy storage capacity
measure of the amount of energy a storage device can store and deliver, within established
design limits and maintenance interval conditions
NOTE The energy storage capacity is specified in terms of energy units such as kJ, MJ, kWh or MWh (i.e. the
kinetic energy stored in a flywheel, the hydraulic energy stored in accumulators or potential energy stored in a
water reservoir).
2.24
excitation force (wave)
force which an incident wave exerts on a static body
2.25
extreme significant wave height
significant wave height (H ) of the most severe sea state expected at a site over a specific
m0
return period or design life
NOTE This definition provides for extreme wave heights to be defined in terms of a 50/100 year storm condition.
2.26
farm
group of similar marine energy converters of the same type (either WECs or TECs) sharing a
connection to the electric grid
NOTE Farm spacing will normally be dictated by installation, mooring and access requirements.
2.27
fast tuning
adaptive control of a device over a typical wave period
NOTE Adaptive tuning, real-time control, or complex conjugate control is examples of fast tuning.
2.28
fetch
unobstructed distance of water surface over which the wind has acted
2.29
focusing absorber device
energy converter that uses a method to concentrate waves onto a central converter to
enhance energy production
2.30
free surface
interface between the air and a body of water
2.31
group velocity (wave)
propagation velocity of water wave groups and the wave energy
NOTE The group velocity of a water wave is the velocity that the energy associated with the wave disturbance
travels in the direction of wave propagation. In deep water using linear wave theory this is one half the wave phase
velocity. In shallow water it is equal to the wave phase velocity.

– 12 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
2.32
harmonic analysis of tides
representation of tidal elevations and velocities by the summation of components whose
amplitudes and periods describe astronomical processes
2.33
highest astronomical tide
HAT
highest sea level due to an astronomical tide that can be expected to occur under average
meteorological conditions and under any combination of astronomical conditions
NOTE The highest astronomical tide is not an extreme sea level, as certain meteorological conditions can cause a
higher sea level. The sea level under these circumstances is known as a storm surge. HAT is determined by
inspecting predicted sea levels over a number of years.
[National Oceanography Centre – Natural Environment Resource Council (NERC), 2011]
2.34
in-stream generation
capture and conversion of the energy of flowing water
NOTE In-stream generation includes tidal, ocean current, and flowing river environments.
2.35
intermediate depth water
spatial location where the kinematics properties of the waves are such that the water depth is
less than half the wave length but equal to or greater than a twentieth of the wave length
NOTE In intermediate water, the dispersion equation is
gT 2πd
, where L = wave length, d = water depth, T = period and g = gravitation acceleration
L = tanh
2π L
2.36
latching
restraining the motion of the primary interface at the extremes of its range of motion to
improve power capture
NOTE Latching is sometimes referred to as phase control because latching is often used to align the excitation
(force or pressure) and response (velocity or flow rate), and this can be understood as reducing the phase
difference between the principal frequency components of these parameters.
2.37
lowest astronomical tide
LAT
lowest sea level due to an astronomical tide that can be expected to occur under average
meteorological conditions and under any combination of astronomical conditions
NOTE The lowest astronomical tide is not an extreme sea level, as certain meteorological conditions can cause a
lower sea level. The sea level under these circumstances is known as a negative surge. LAT is determined by
inspecting predicted sea levels over a number of years. LAT is commonly used as the datum point from which sea
level is measured.
[National Oceanography Centre – NERC, 2011]
2.38
maintainability
probability that a given active maintenance action, for an item under given conditions of use,
can be carried out within a given duration, when the maintenance is performed under stated
conditions and using stated procedures and resources
[IEC 60050-191:1990, 191-13-01, modified]

© IEC 2019
2.39
marine current
persistent flow of seawater produced by natural physical processes, including the gravitational
pull of celestial bodies
2.40
maximum average power
time-averaged power produced by a device under peak operating conditions over a given
interval
NOTE 1 For a wave device, peak operating conditions represent the maximum operating sea conditions.
NOTE 2 For a tidal device, peak operating conditions would be the maximum flow rates.
2.41
maximum individual wave height
H
max
statistical measure of the largest individual wave heights which can be observed or expected
in a given sea state for a stated probability of exceedance
NOTE Maximum individual wave height is normally calculated from a Rayleigh distribution for wave heights in
deep water for an exceedance probability of one per thousand, for which a H = 1,86 H .
max m0
2.42
mean annual wave power
long-term average of the directionally unresolved wave energy flux per unit width, calculated
as an arithmetic mean over all sea states occurring at a given location
NOTE Typically mean annual wave power units are expressed in kilowatts per metre.
2.43
mean high water neaps
MHWN
annual average height (when the average maximum declination of the moon is 23,5 degrees)
of two successive high waters during those time intervals of 24 h when the range of the
astronomical tide is at its least
NOTE The values of mean high water neaps vary from year to year with a cycle of approximately 18,6 years.
[National Oceanography Centre – NERC, 2011, modified]
2.44
mean high water springs
MHWS
annual average height (when the average maximum declination of the moon is 23,5 degrees)
of two successive high waters during those time intervals of 24 h when the range of the
astronomical tide is at its greatest
NOTE The values of mean high water springs vary from year to year with a cycle of approximately 18,6 years.
[National Oceanography Centre – NERC, 2011, modified]
2.45
mean low water neaps
MLWN
annual average height (when the average maximum declination of the moon is 23,5 degrees)
of two successive low waters during those time intervals of 24 h when the range of the
astronomical tide is at its least
NOTE The values of mean low water neaps vary from year to year with a cycle of approximately 18,6 years.
[National Oceanography Centre – NERC, 2011, modified]

– 14 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
2.46
mean low water springs
MLWS
annual average height (when the average maximum declination of the moon is 23,5 degrees)
of two successive low waters during those time intervals of 24 h when the range of the
astronomical tide is at its greatest
NOTE The values of mean low water springs vary from year to year with a cycle of approximately 18,6 years.
[National Oceanography Centre – NERC, 2011, modified]
2.47
mean neap range
difference between mean high water neaps (MHWN) and mean low water neaps (MLWN)
[National Oceanography Centre – NERC, 2011]
2.48
mean spring peak velocity
Vmsp
annual average (when the average maximum declination of the moon is 23,5 degrees) of four
successive maximum flow speeds during those time intervals of 24 h when the range of the
astronomical tide is at its greatest
NOTE Mean spring peak velocity should be calculated at a depth 5 m below the surface as the average over 30
min of the four peak speeds occurring during the two ebb and the two flood tides, associated with the largest spring
tide.
2.49
mean spring range
difference between mean high water springs (MHWS) and mean low water springs (MLWS)
[National Oceanography Centre – NERC, 2011]
2.50
mean water level
surface level of a body of water with motions such as wind waves and/or changes due to the
tides averaged out
NOTE When considering tides, the mean water level is normally measured at a tidal gauging station over a period
of several years. When considering waves, the sea level is generally averaged over a much shorter time period
(e.g. 1 h).
2.51
mean zero crossing period (see Figure 3)
average time interval between down crossings of the mean water level during a given sea
state
NOTE The spectral estimate of the mean zero crossing period, T , is calculated as
m
T =
m
2.52
met-ocean
meteorological and oceanographic environment typically described using wind, wave, tidal
characteristics, etc.
2.53
mixed tides
occurrence of relatively large diurnal inequality in the high or low waters or both

© IEC 2019
2.54
ocean current
large scale and persistent flow of seawater produced by mechanisms other than the
gravitational forces of celestial bodies
NOTE Ocean currents result from processes such as wind, density gradients, salinity gradients, Coriolis forces,
etc.
2.55
oscillating hydrofoil
energy converter in which force is induced due to a pressure difference on the foil section
caused by the relative motion of the fluid over the foil inducing oscillatory motion
[University of Strathclyde, Energy Systems Research Unit, 2011, modified]
2.56
oscillating water column device
OWC
energy converter with an enclosed air volume excited by waves causing reciprocating air to
flow through a turbine
2.57
oscillating wave surge converter
OWSC
device which responds to the predominantly horizontal fluid motions in shallow and
intermediate depth water
2.58
overtopping device
energy converter with a reservoir filled by wave overtopping, which typically discharges
through a low head turbine
2.59
park (marine energy)
designated geographical region containing one or more marine energy farms
2.60
peak operating conditions
met-ocean and/or river conditions under which a machine operates so as to generate its
maximum power output
2.61
peak period (wave)
T
p
inverse of the peak frequency (wave), T = 1 / f
p p
2.62
peak frequency (wave)
f
p
frequency corresponding to the maximum value of the omni-directional wave spectrum
2.63
phase velocity (water wave)
celerity
speed at which the shape of the wave propagates

– 16 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
2.64
point absorber device
WEC that is small relative to the wave length and typically absorbs wave energy independent
of the direction of wave incidence
2.65
power matrix
tabular description of power capture as a function of relevant met-ocean parameters
NOTE 1 For a wave energy converter, the power matrix should be described using at least wave height and
energy period.
NOTE 2 For a tidal energy converter, the power matrix should be described using at least flow speed and
direction.
2.66
power curve
power surface
graphical description of the power capture as a continuous function of relevant met-ocean
parameters
NOTE 1 For a wave energy converter, the power curve should be described using at least wave height and
energy period.
NOTE 2 For a tidal energy converter, the power curve should be described using at least the flow speed.
2.67
power take-off
PTO
mechanism that converts the motion of the prime mover into a useful form of energy such as
electricity
2.68
prime mover
physical component that acts as the interface between the marine resource and the energy
converter from which energy is captured
NOTE For wave energy converters the prime mover may be a heaving buoy, a hinged flap, an OWC runner, etc.,
and for tidal energy converters the prime mover is typically the runner.
2.69
rated capacity (system)
designated power output of a marine energy converter
NOTE The term capacity can refer to the output of a single device, an array of devices, or an entire marine farm.
2.70
reliability
probability that an item can perform a necessary function under given conditions for a given
time interval
[IEC 60050-191:1990,191-12-01, modified]
2.71
resource assessment (marine energy)
collection and processing of met-ocean data required for determining the performance of a
marine energy converter or farm
NOTE Resource assessment may be conducted in three distinct stages including theoretical resource
assessment, technical resource assessment, and practical resource assessment.

© IEC 2019
2.71.1
practical resource assessment
proportion of the technical resource that is available after consideration of external constraints
NOTE 1 External constraints may include grid accessibility, competing use, environmental sensitivity, etc.
NOTE 2 Practical resource assessment is one of three distinct stages in a resource assessment. The remaining
two stages include theoretical resource assessment and technical resource assessment. The value of the
theoretical resource assessment is greater than the technical resource assessment, which in turn is greater than
the practical resource assessment.
[Legrand, 2009, modified]
2.71.2
technical resource assessment
proportion of the theoretical resource that can be captured using existing technology options
without consideration of external constraints
NOTE Technical resource assessment is one of three distinct stages in a resource assessment. The remaining
two stages include practical resource assessment and theoretical resource assessment. The value of the
theoretical resource assessment is greater than the technical resource assessment, which in turn is greater than
the practical resource assessment.
[Legrand, 2009, modified]
2.71.3
theoretical resource assessment
energy contained in the entire resource
NOTE Theoretical resource assessment is one of three distinct stages in a resource assessment. The remaining
two stages include practical resource assessment and technical resource assessment. The value of the theoretical
resource assessment is greater than the technical resource assessment, which in turn is greater than the practical
resource assessment.
[Legrand, 2009, modified]
2.72
resource characterization
parameterization of met-ocean data to enable determination of the performance of a marine
energy converter or farm
2.73
scatter diagram
tabular representation of the frequency of occurrence for given met-ocean conditions at a
specific site
NOTE 1 For wave energy converters, the met-ocean conditions typically used are significant wave height and a
characteristic wave period.
NOTE 2 A scatter diagram is sometimes referred to as a joint occurrence table.
2.74
sea state
stationary condition of the wind waves and swell at a site, characterized by relevant
parameters such as the significant wave height and energy period (wave)
2.75
sea trial
evaluation of a device’s performance and properties in the natural environment
2.76
semi-diurnal tides
occurrence of two high waters and two low waters of approximately equal height each tidal
day
– 18 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
NOTE A tidal day is equal to 24,8 h.
2.77
shallow water
spatial location defined by the kinematic properties of waves where the water depth is less
than a twentieth of the wave length
NOTE In shallow water, the dispersion equation is
gT 2πd
L = tanh
2π L
where
L is the wave length;
d is the water depth;
T is the period;
g is the gravitation acceleration.
In shallow water, the dispersion equation may be simplified to .
L = T gd
2.78
significant wave height
statistical measure of the average of the largest one-third of wave heights in an irregular sea
state
NOTE 1 From time domain analysis the significant wave height, H , is calculated based on zero down crossing
s
analysis.
NOTE 2 The spectral estimate of the significant wave height is to be preferred and is estimated by
where m is the zeroth spectral moment of the wave energy spectrum. m is the variance of the sea
H = 4 m
0 0
m 0
state and can be calculated directly from the surface elevation time series. If the individual wave heights are
Rayleigh distributed then H = H . In most realistic sea states this is not completely true and H is therefore
s m0 m0
often slightly larger than H .
s
2.79
spectral density
limit of the variance of the free surface elevation as the frequency bin width tends to zero
2.80
spectral moment
th
n spectral moment, m , about zero frequency, is given by
n
∞
n
m = f S( f )d f
n
∫
where S(f) is the spectral density.
NOTE For discrete data the following estimate may be used
n
m = f S ∆f
n ∑ i i i
i
2.81
submerged pressure differential device
immersed WEC which converts pressure variations into some other form of energy, typically
electricity
© IEC 2019
2.82
survivability (functional)
probability that a converter will continue to operate without a forced outage over the stated
operational life
[Legrand, 2009, modified]
2.83
survivability (safety)
probability that a converter will remain as installed over the stated operational life
[Legrand, 2009, modified]
2.84
survival mode
operation mode for a device that reduces the likelihood of damage being sustained during
extreme/uncommon environmental conditions such as storms
2.85
tank testing
evaluation of device performance and properties under controlled hydrodynamic conditions
NOTE Tank tests may be performed in wave flumes, towing tanks, wave basins, and other types of facilities.
2.86
terminator device
energy converter which is aligned perpendicular to the predominant direction of wave
incidence
2.87
tidal current
tidal stream
flow of water induced by the gravitational forces of celestial bodies
2.88
tidal current constituents
complex amplitudes and phases of the components of the harmonic description of tidal
velocities at a specified location
2.89
tidal current ellipse
polar plot of the tidal velocities at spring and neap tide
NOTE Typically the depth averaged velocities are used to create the plot.
2.90
tidal current turbulence
unsteady fluctuation of the flow velocity in a tidally induced current
2.91
tidal eddy
circular movement of water present in a tidally induced current
2.92
tidal energy
energy present in the movement of water created by the gravitational forces of celestial
bodies a tidal current
– 20 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
2.93
tidal energy converter
TEC
device which captures energy from tidal currents and converts it into another form
device that converts energy from a tidal current to electricity or other useful forms of energy
2.94
tidal height constituents
amplitudes and phases of the components of the harmonic description of tidal elevations at a
specified location
2.95
tidal range
difference between consecutive high and low tides
2.96
turbine
rotating device that converts kinetic energy of flowing fluid to mechanical energy
2.96.1
axial flow turbine
kinetic energy conversion device in which the fluid moves in a direction parallel to the axis of
rotation
[IEC 60050-811:1991, 811-22-04, modified]
2.96.2
bulb turbine
hydraulic reaction type kinetic energy conversion device set with its casing containing the
generator and turbine immersed in the water flow
[IEC 60050-602:1983, 602-02-16]
2.96.3
counter-rotating turbine; contra-rotating turbine
set of kinetic energy conversion devices placed close together with their blades rotating in
opposite directions
2.96.4
cross-flow turbine
kinetic energy conversion device in which the fluid moves in a direction perpendicular to the
axis of rotation
2.96.5
Darrieus turbine
type of cross-flow turbine with non-helical blades in line with the axis of rotation
2.96.6
Francis turbine
hydraulic reaction type kinetic energy conversion device with fixed runner blades usually
operating from a medium or low head source with medium flow rate
[IEC 60050-602:1983, 602-02-14, modified]
2.96.7
Gorlov turbine
type of cross-flow turbine with helical blades

© IEC 2019
2.96.8
horizontal axis tidal turbine
kinetic energy conversion device whose rotor axis is substantially parallel to the fluid flow
[IEC 60050-415:1999, 415-01-04, modified]
2.96.9
Kaplan turbine
axial hydraulic reaction type kinetic energy conversion device with adjustable runner blades
operated with a high flow rate
[IEC 60050-602:1983, 602-02-15, modified]
2.96.10
Pelton turbine
hydraulic impulse type kinetic energy conversion device usually operated from a high head
source with small flow rate
[IEC 60050-602:1983, 602-02-13, modified]
2.96.11
propeller turbine
kinetic energy conversion device with non-adjustable runner blades suitable for non-varying
head sources
[IEC 60050-602:1983, 602-02-17, modified]
2.96.12
pit turbine
type of bulb type kinetic energy conversion device in which the gearbox is used to reduce the
size of the generator and the bulb
2.96.13
rim turbine
type of axial flow type kinetic energy conversion device in which the power take-off is taken
from the perimeter of the turbine
2.96.14
Savonius turbine
type of cross-flow kinetic energy conversion device with S-shaped scoops, which have an
offset against each other so that a part of the fluid is diverted to the other concave blade
2.96.15
tubular turbine
type of axial flow kinetic energy conversion device in which the power take-off is taken from a
long shaft connected to the runner
[Wave Energy Centre, 2007]
2.96.16
Turgo turbine
hydraulic impulse type kinetic energy converter operated from a medium head source in which
the head range is where Pelton and Francis turbines overlap
2.96.17
vertical axis tidal turbine
kinetic energy conversion device whose rotor axis is vertical and perpendicular to the flow of
water
[IEC 60050-415:1999, 415-01-05, modified]

– 22 – IEC TS 62600-1:2011+AMD1:2019 CSV
© IEC 2019
2.96.18
Wells turbine
kinetic energy conversion device with symmetric fixed-pitch blades that rotates in a single
direction regardless of the direction of fluid flow
[Carbon Trust, 2005, modified]
2.97
Venturi device
convergent-divergent duct section used to create a pressure difference that drives a turbine
2.98
water current measuring instrument
device used to measure water current properties
2.98.1
Doppler current meter
acoustic device which measures water current at only one level in the water column
2.98.2
Doppler current profiler
DCP
acoustic device which measures current speed and direction in multiple layers throughout the
water column
2.98.3
Doppler velocimeter
acoustic device which produces high resolution measurement of the current speed and
direction at a single point
2.99
wave climate
long-term statistical characterization of the wave properties at a location
NOTE Wave climate is a subset of met-ocean.
2.100
wave energy
total kinetic and potential energy associated with the propagation of surface waves, integrated
from the sea floor to the surface
energy present in surface waves
2.101
wave energy converter
WEC
device which captures energy from surface waves and converts it into another form
device that converts energy from surface waves to electricity or other useful forms of energy
2.102
wave energy spectrum
wave energy per unit area as a function of frequency, expressed as ρgS(f), where S(f) is the
spectral density
NOTE The wave energy spectrum may be expressed as a function of frequency and direction, and other
parameters.
2.103
wave height
vertical distance between a consecutive wave trough and wave crest (see Figure 3)

© IEC 2019
A
B
...