IEC TS 62257-7:2008

IEC/TS 62257-7
Edition 1.0 2008-04
TECHNICAL
SPECIFICATION
Recommendations for small renewable energy and hybrid systems for rural
electrification –
Part 7: Generators
IEC/TS 62257-7:2008(E)
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IEC/TS 62257-7
Edition 1.0 2008-04
TECHNICAL
SPECIFICATION
Recommendations for small renewable energy and hybrid systems for rural
electrification –
Part 7: Generators
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
M
ICS 27.160; 27.180 ISBN 2-8318-9671-1

– 2 – TS 62257-7 © IEC:2008(E)
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 .9
Table 3 – Output requirements relative to the generator technology.11
Table 4 – Specific generators requirements considered in the IEC 62257 series.12

TS 62257-7 © IEC:2008(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RECOMMENDATIONS FOR SMALL RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 7: Generators
FOREWORD
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international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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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 document is based on IEC/PAS 62111; it cancels and replaces the relevant parts of
IEC/PAS 62111.
– 4 – TS 62257-7 © IEC:2008(E)
This technical specification is to be used in conjunction with the future parts of this series as
and when they are published.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
82/492/DTS 82/507/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.
A list of all parts of IEC 62257 series, under the general title: Recommendations for small
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 maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• 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 62257-7 © IEC:2008(E) – 5 –
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
a.c. voltage below 500 V, d.c. voltage below 750 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.

– 6 – TS 62257-7 © IEC:2008(E)
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 point out the main items that must be considered when selecting, sizing,
installing, operating and maintaining this equipment.
This technical specification 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 referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC/TS 62257-2:2004, Recommendations for small renewable energy and hybrid systems for
rural electrification – Part 2: From requirements to a range of electrification systems
IEC/TS 62257-4, Recommendations for small renewable energy and hybrid systems for rural
electrification – Part 4: System selection and design
IEC/TS 62257-5, Recommendations for small renewable energy and hybrid systems for rural
electrification – Part 5: Protection against electric hazards
IEC/TS 62257-7-1, Recommendations for small renewable energy and hybrid systems for
rural electrification – Part 7-1: Generators – Photovoltaic arrays
IEC/TS 62257-7-3, Recommendations for small renewable energy and hybrid systems for
rural electrification – Part 7-3: Generating set – Selection of generating sets for rural
electrification systems
IEC/TS 62257-9-1 , Recommendations for small renewable energy and hybrid systems for
rural electrification – Part 9-1: Micropower systems
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
___________
To be published.
TS 62257-7 © IEC:2008(E) – 7 –
3.1
generator
apparatus that converts one form of energy into electricity
[IEC 61836, 3.3.25, modified]
3.2
dispatchable power system
power system where delivered electr
...