IEC TS 62257-7:2017

Recommendations for renewable energy and hybrid systems for rural electrification - Part 7: Generators

IEC TS 62257-7:2017 specifies the general requirements for the generators in decentralized rural electrification systems. This document is a general introduction followed by more specific documents dedicated to the generation technologies which are the most currently used in rural electrification projects. This new edition includes the following significant technical changes with respect to the previous edition: removed the word "small" from the description of the PV systems, and removed the power limit (100 kVA); increased the relevant voltage levels to 1 000 V (AC) and 1 500 V (DC).

General Information

• Status: Published
• Publication Date: 21-Sep-2017
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 27.160 - Solar energy engineering
• Technical Committee: TC 82 - Solar photovoltaic energy systems
• Drafting Committee: JWG 1 - TC 82/JWG 1
• Current Stage: PPUB - Publication issued
• Start Date: 26-Oct-2017
• Completion Date: 22-Sep-2017

Relations

• Revises: IEC TS 62257-7:2008 - Recommendations for small renewable energy and hybrid systems for rural electrification - Part 7: Generators
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC TS 62257-7 ®
Edition 2.0 2017-09
TECHNICAL
SPECIFICATION
Recommendations for renewable energy and hybrid systems for rural
electrification –
Part 7: Generators
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 Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
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 corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 20 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 65 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
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details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: [e-mail].
IEC TS 62257-7 ®
Edition 2.0 2017-09
TECHNICAL
SPECIFICATION
Recommendations for renewable energy and hybrid systems for rural

electrification –
Part 7: Generators
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-4844-7

– 2 – IEC TS 62257-7:2017  IEC 2017
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General . 8
5 Generator boundaries . 8
6 Generators requirements . 9
6.1 General requirements . 9
6.2 Specific requirements for the different technologies . 9
6.2.1 Input requirements . 9
6.2.2 Output requirements . 11
6.2.3 Specific requirements for different generator technologies . 11
7 Generator design and sizing . 12
8 Hybrid generation . 12
Bibliography . 13

Figure 1 – General electrical configuration of a collective electrification system . 8

Table 1 – General inputs and outputs to be considered for generator specification . 9
Table 2 – Input requirements relative to the generator technology . 10
Table 3 – Output requirements relative to the generator technology . 11
Table 4 – Specific generators requirements considered in the IEC 62257 series . 12

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RECOMMENDATIONS FOR RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 7: Generators
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 62257-7, which is a technical specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.

– 4 – IEC TS 62257-7:2017  IEC 2017

This second edition cancels and replaces the first edition published in 2008. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Removed the word "small" from the description of the PV systems, and removed the power
limit (100 kVA).
b) Increased the relevant voltage levels to 1 000 V (AC) and 1 500 V (DC).
This technical specification is to be used in conjunction with other parts of this series.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
82/1201/DTS 82/1258/RVDTS
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 document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 62257 series, under the general title: Recommendations for
renewable energy and hybrid systems for rural electrification, can be found on the IEC
website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.

INTRODUCTION
The IEC 62257 series of documents intends to provide to different players involved in rural
electrification projects (such as project implementers, project contractors, project supervisors,
installers, etc.) documents for the setting-up of renewable energy and hybrid systems with AC
voltage below 1 000 V and DC voltage below 1 500 V.
These documents are recommendations:
– to choose the right system for the right place;
– to design the system;
– to operate and maintain the system.
These documents are focused only on rural electrification, concentrating on but not specific
to, developing countries. They must not be considered as all-inclusive to rural electrification.
The documents try to promote the use of renewable energies in rural electrification; they do
not deal with clean development mechanisms at this time (CO emission, carbon credit, etc.).
Further developments in this field could be introduced in future steps.
This consistent set of documents is best considered as a whole with different parts
corresponding to items for safety, sustainability of systems and at the lowest life-cycle cost as
possible. One of the main objectives is to provide the minimum sufficient requirements,
relevant to the field of application, that is, renewable energy and hybrid off-grid systems.
The purpose of this part of IEC 62257 is to provide project implementers with general
information about generators and to highlight the main characteristics relative to the different
technologies that can be used.

– 6 – IEC TS 62257-7:2017  IEC 2017
RECOMMENDATIONS FOR RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 7: Generators
1 Scope
This part of IEC 62257 specifies the general requirements for the generators in decentralized
rural electrification systems.
This document is a general introduction followed by more specific documents dedicated to the
generation technologies which are the most currently used in rural electrification projects.
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 TS 62257-2:2015, Recommendations for renewable energy and hybrid systems for rural
electrification – Part 2: From requirements to a range of electrification systems
IEC TS 62257-4, Recommendations for renewable energy and hybrid systems for rural
electrification – Part 4: System selection and design
IEC TS 62257-
...

IEC TS 62257-7 ®
Edition 2.0 2017-09
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Recommendations for small renewable energy and hybrid systems for rural
electrification –
Part 7: Generators
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 Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
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 corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 20 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 65 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: [e-mail].
IEC TS 62257-7 ®
Edition 2.0 2017-09
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Recommendations for small renewable energy and hybrid systems for rural

electrification –
Part 7: Generators
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-4859-1

– 2 – IEC TS 62257-7:2017 RLV  IEC 2017
CONTENTS
FOREWORD . 3
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 General . 9
5 Generator boundaries . 9
6 Generators requirements . 10
6.1 General requirements . 10
6.2 Specific requirements for the different technologies . 10
6.2.1 Input requirements . 10
6.2.2 Output requirements . 12
6.2.3 Specific requirements for different generator technologies . 12
7 Generator design and sizing . 13
8 Hybrid generation . 13
Bibliography . 14

Figure 1 – General electrical configuration of a collective electrification system . 9

Table 1 – General inputs and outputs to be considered for generator specification . 10
Table 2 – Input requirements relative to the generator technology . 11
Table 3 – Output requirements relative to the generator technology . 12
Table 4 – Specific generators requirements considered in the IEC 62257 series . 13

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RECOMMENDATIONS FOR SMALL RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 7: Generators
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 redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.

– 4 – IEC TS 62257-7:2017 RLV  IEC 2017
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 62257-7, which is a technical specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.

This second edition cancels and replaces the first edition published in 2008. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Removed the word "small" from the description of the PV systems, and removed the power
limit (100 kVA).
b) Increased the relevant voltage levels to 1 000 V (AC) and 1 500 V (DC).
This technical specification is to be used in conjunction with other parts of this series.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
82/1201/DTS 82/1258/RVDTS
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 document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 62257 series, under the general title: Recommendations for
renewable energy and hybrid systems for rural electrification, can be found on the IEC
website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.

– 6 – IEC TS 62257-7:2017 RLV  IEC 2017
INTRODUCTION
The IEC 62257 series of documents intends to provide to different players involved in rural
electrification projects (such as project implementers, project contractors, project supervisors,
installers, etc.) documents for the setting-up of renewable energy and hybrid systems with AC
voltage below 500 1 000 V and DC voltage below 750 1 500 V and power below 100 Kva.
These documents are recommendations:
– to choose the right system for the right place;
– to design the system;
– to operate and maintain the system.
These documents are focused only on rural electrification, concentrating on but not specific
to, developing countries. They must not be considered as all-inclusive to rural electrification.
The documents try to promote the use of renewable energies in rural electrification; they do
not deal with clean development mechanisms at this time (CO emission, carbon credit, etc.).
Further developments in this field could be introduced in future steps.
This consistent set of documents is best considered as a whole with different parts
corresponding to items for safety, sustainability of systems and at the lowest life-cycle cost as
possible. One of the main objectives is to provide the minimum sufficient requirements,
relevant to the field of application, that is, small renewable energy and hybrid off-grid
systems.
The purpose of this part of IEC 62257 is to provide project implementers with general
information about generators and to highlight the main characteristics relative to the different
technologies that can be used.

RECOMMENDATIONS FOR SMALL RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 7: Generators
1 Scope
The purpose of this part of IEC 62257 is to specify the general requirements for generators
(maximum power = 100 kVA) in decentralized rural electrification systems.
The aim is to poin
...