SIST-TS IEC/TS 62257-7-3:2008

SLOVENSKI STANDARD
01-november-2008
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Recommendations for small renewable energy and hybrid systems for rural electrification
- Part 7-3: Generator set - Selection of generator sets for rural electrification systems
Ta slovenski standard je istoveten z: IEC/TS 62257-7-3
ICS:
27.190 Biološki viri in drugi Biological sources and
alternativni viri energije alternative sources of energy
29.160.40 (OHNWULþQLDJUHJDWL Generating sets
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

Edition 1.0 2008-04
TECHNICAL
SPECIFICATION
Recommendations for small renewable energy and hybrid systems for rural
electrification –
Part 7-3: Generator set – Selection of generator sets for rural electrification
systems
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
W
ICS 27.160; 27.180 ISBN 2-8318-9672-X

– 2 – TS 62257-7-3 © IEC:2008(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references .8
3 Terms and definitions .9
4 Introduction to generator sets .11
4.1 Generator set system .11
4.2 Generator set application in rural electrification systems .11
4.3 Resource assessment .11
5 Selection and erection .12
5.1 General .12
5.2 Selection requirements.12
5.2.1 Power quality.12
5.2.2 Generator set sizing .12
5.2.3 Generator set type.14
5.2.4 Derating factors.14
5.2.5 Starting system.15
5.2.6 Control systems.15
5.2.7 Noise issues.15
5.2.8 Environmental issues .15
5.3 Erection.15
5.3.1 Shipping .15
5.3.2 Design of the erection site .16
5.3.3 Installation requirements .17
6 Safety.20
6.1 General .20
6.2 Electrical issues .20
6.2.1 General requirements .20
6.2.2 Connection system to the application.20
6.2.3 Power cables.21
6.2.4 Neutral system .21
6.2.5 Earthing.21
6.2.6 Overcurrent protection.21
6.2.7 Residual Current protection Device (RCD).22
6.2.8 Isolating devices.22
6.3 Mechanical issues .22
6.3.1 Vibration.22
6.3.2 Protection from mechanical damage .22
6.3.3 Protection from moving parts .22
6.4 Thermal issues.23
6.5 Fire risk.23
7 Acceptance .23
7.1 General .23
7.2 Conformity of the generator set to the identification file .23
7.3 Conformity of the generator set system to the GS.23
7.4 Acceptance process .23

TS 62257-7-3 © IEC:2008(E) – 3 –
7.4.1 Preparation of the generator set for commissioning .23
7.4.2 Commissioning inspection of the generator set system .24
7.4.3 Commissioning tests of the generator set system .24
7.4.4 Test file .25
8 Operation and maintenance.25
8.1 Access to the generator set.25
8.2 Operation process .25
8.3 Monitoring .26
8.4 Maintenance schedule.26
9 Replacement .26
10 Marking .27
10.1 Generator set .27
10.2 Engine.27
10.3 Alternator .27
10.4 Shutdown apparatus.28
11 Documentation .28
11.1 General .28
11.2 Installation .28
11.3 Operation .29
11.4 Inspection and maintenance .29
Annex A (informative) Generator set classification criteria .30
Annex B (informative) Identification file.34
Annex C (informative) Maintenance schedule .35
Annex D (informative) Example of commissioning records sheet.36
Bibliography.38

Figure 1 – General functional configuration of a generator set powered system .7

Table 1 – Examples of derating factors for generator sets.14
Table 2 – Generator set permitted noise levels .15
Table 3 – Cross-section of power cables.21
Table A.1 – Classification of generator set services .30
Table A.2 – Common lifespan values .31
Table C.1 – Example of maintenance schedule.35

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

Part 7-3: Generator set –
Selection of generator sets for rural electrification systems

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
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 62257-7-3, which is a technical specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.

TS 62257-7-3 © IEC:2008(E) – 5 –
This document is based on IEC/PAS 62111; it cancels and replaces the relevant parts of
IEC/PAS 62111.
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
82/493/DTS 82/508/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.

– 6 – TS 62257-7-3 © IEC:2008(E)
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
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.
TS 62257-7-3 © IEC:2008(E) – 7 –
RECOMMENDATIONS FOR SMALL RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 7-3: Generator set –
Selection of generator sets for rural electrification systems

1 Scope
The purpose of this part of IEC 62257 is to specify the general requirements for the selection,
sizing, erection and operation of generator sets in decentralized rural electrification systems.
It applies to all low voltage combustion engine electricity generator sets with a rated power up
to 100 kVA, and designed for supplying electrical power to isolated sites used in systems as
described in IEC/TS 62257-2.
This technical specification is not an exhaustive resource for the design, installation,
operation or maintenance of generator sets but is more focused on recommendations to
provide strategies on selection and criteria which may affect the use of such generation
systems in a rural electrification project.
Two cases will be considered as illustrated by Figure 1 to power a collective electrification
system (microgrid) or an individual electrification system.
• the micropowersystem is composed of one generator set
• the micropowersystem is a hybrid one and the generator set is only part of it. This case is
addressed in the document dedicated to micropower system (IEC/TS 62257-9-1).

Generating set alone
• Individual electrification
system (IES)
Generating
Or
set
• Collective electrification
system (CES)
Main switch
Generating set in an hybrid system
• Individual electrification
Secondary
system (IES)
switch
Generating
Or
set
• Collective electrification
system (CES)
Main switch
Other power
sources
IEC  444/08
Figure 1 – General functional configuration of a generator set powered system

– 8 – TS 62257-7-3 © IEC:2008(E)
The aim of this technical specification is to provide users with the appropriate levels of
reliability and safety of the equipment during its estimated service lifespan.
It describes the minimum safety requirements and does not claim to be an exhaustive
instruction manual or design specification.
Compliance with this technical specification does not exempt any person, organization or
corporation from the responsibility to comply with all other relevant regulations.
This technical specification gives recommendations for the following types of generator sets:
a) single phase;
b) three phase;
c) LV range up to 500 V - 50/60 Hz (see IEC/TS 62257-9-2).
2 Normative references
The following referenced documents are essential 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 60034-1, Rotating electrical machines – Part 1: Rating and performance
IEC 60034-9, Rotating electrical machines – Part 9: Noise limits
IEC 60034-22, Rotating electrical machines – Part 22: AC generators for reciprocating internal
combustion (RIC) engine driven generating sets
IEC 60529, Degrees of protection provided by enclosures (IP code)
IEC 61009-1, Residual current operated circuit-breakers with integral overcurrent protection
for household and similar uses (RCBOs) – Part 1: General rules
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 62257-5, Recommendations for small renewable energy and hybrid systems for rural
electrification – Part 5: Protection against electric hazards
IEC/TS 62257-6, Recommendations for small renewable energy and hybrid systems for rural
electrification – Part 6: Acceptance, operation, maintenance and replacement
, Recommendations for small renewable energy and hybrid systems for
IEC/TS 62257-9-1
rural electrification – Part 9-1: Micropower systems
IEC/TS 62257-9-2, Recommendations for small renewable energy and hybrid systems for
rural electrification – Part 9-2: Microgrid
ISO 8528-1:2005, Reciprocating internal combustion engine driven alternating current
generating sets – Part 1: Application, ratings and performance
ISO 8528-3:2005, Reciprocating internal combustion engine driven alternating current
generating sets – Part 3: Alternating current generators for generating sets
___________
To be published.
TS 62257-7-3 © IEC:2008(E) – 9 –
ISO 8528-5, Reciprocating internal combustion engine driven alternating current generating
sets – Part 5: Generating sets
ISO 8528-7:1994, Reciprocating internal combustion engine driven alternating current
generating sets – Part 7: Technical declarations for specification and design
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
environmental conditions
environment characteristics (altitude, temperature, humidity, etc.) which may affect the
performance
3.2
generator set
equipment producing electricity from a fossil fuel; it consists basically of an internal
combustion engine producing mechanical energy and a generator which converts the
mechanical energy into electrical energy and mechanical transmission, support and assembly
components
3.3
identification file
IF
document provided by the manufacturer which guarantees the conformity of the equipment
supplied with that which has undergone the type tests
3.4
lifespan
effective period of functioning taking into account the probability of a catastrophic failure
3.5
non-routine maintenance
maintenance necessary in addition to that pre-planned
3.6
rated frequency
frequency at which the generator set is designed to operate
3.7
routine maintenance
preventive maintenance carried out to an established plan
3.8
rated electrical power (nominal power or rated capacity)
maximum continuous power supplied by a generator set in compliance with its specifications,
and under standard operating conditions. This is expressed in VA (volt-ampere) or more
usually in kVA
3.9
rated rotation speed
alternator rotation speed necessary to produce the voltage at the rated frequency
3.10
rated voltage
voltage between phases on the alternator terminals at the rated frequency and rated power

– 10 – TS 62257-7-3 © IEC:2008(E)

3.11
extra low voltage
ELV
voltage not exceeding a limit which is generally accepted to be 50 V a.c. and 120 V d.c. ripple
free
3.12
live conductive part
conductor or conductive part intended to be energized in normal operation, including a neutral
conductor, but by convention not a PE or a PEN conductor
3.13
protected extra-low voltage
PELV
extra-low voltage system which is not electrically separated from earth, but which otherwise
satisfies all the requirements for SELV
3.14
power factor
ratio of real power to apparent power in an a.c. circuit
3.15
real power
for a.c. circuits, the product of voltage, current and power factor, also equal to the rate of flow
of electrical energy. Real power is measured in watt (W)
3.16
apparent power
for a.c. circuits, the product of voltage by current, measured in volt-ampere (VA)
3.17
nominal power of the generator set
maximum apparent power that can be provided by the generator set according to the
manufacturer’s specification
3.18
safety extra-low voltage
SELV
extra-low voltage system which is electrically separated from earth and from other systems in
such a way that a single fault cannot give rise to the risk of electric shock
3.19
minor fuel storage
fuel storage located in the generator set room
3.20
main fuel storage
fuel storage located outside the generator set room and able to provide fuel filling the minor
fuel storage
TS 62257-7-3 © IEC:2008(E) – 11 –

3.21
voltage
differences of potential normally existing between conductors and between conductors and
earth as follows:
a) Extra-low voltage: not exceeding 50 V a.c. or 120 V ripple-free d.c.
b) Low voltage: exceeding upper limits of extra-low voltage, but not exceeding 1 000 V
a.c. or 1 500 V d.c.
c) High voltage: exceeding upper limits of low voltage
3.22
protective conductor (identification: PE)
conductor provided for purposes of safety, for example protection against electric shock
[IEV 195-02-09]
3.23
PEN conductor
conductor combining the functions of both a protective earthing conductor and a neutral
conductor
[IEV 195-02-12]
4 Introduction to generator sets
4.1 Generator set system
In the present document a generator set system includes the installed generator set itself, the
related civil works or prefabricated enclosure if any and all relative ancillaries such as fuel
tank, pipes, earthing systems, etc. necessary for the operation of the generator set.
4.2 Generator set application in rural electrification systems
The usage of generator sets in rural electrification systems application, are described in
IEC/TS 62257-2 for T3, T4, T5 and T6 categories of systems.
In these system categories the generator sets are used to recharge batteries and/or provide a
backup power supply to all or part of the a.c. distribution system, or to supply a.c. dedicated
equipment.
The type of use of the generator set shall be clearly identified by the project developer and
notified to the supplier.
4.3 Resource assessment
Before choosing a generator set as the generator in an electrification system, it is important to
check the availability of the fuel supply on the installation site. It is important to check if the
supply is possible all throughout the year. For example in some countries it could be
impossible to deliver fuel to the site during the rainy season.
The project implementer also shall take into account that the cost of fuel may vary with the
price of the oil market and also with changes in local subsidies.

– 12 – TS 62257-7-3 © IEC:2008(E)
5 Selection and erection
5.1 General
A lot of technologies are available on the market for engines, from the most simple to the
most sophisticated.
For small size (~below 5 kVA) the most commonly used technology is gasoline engines.
For larger size, the most commonly used technology is diesel engines.
Other fuels can be used such as oil, or ethanol.
The engines are designed either for 3 000 rpm (generally for small machines) or 1 500 rpm
(generally for larger machines) at 50 Hz case.
Other technologies like small fuel turbines may be also available.
The project implementer shall select the appropriate technology corresponding to the required
level of quality of the service, the skill of the maintenance staff, the level of equipment
available at the maintenance centre, the spare parts than can be easily sourced, and all
specific constraints of the project. Annex A provides some information about the classification
of different types of generator sets as they are available on the market.
5.2 Selection requirements
5.2.1 Power quality
Type and configuration of generator set shall be selected in relation with the requirements of
the power supply to the end user as given in the General Specification (GS) of the project.
These requirements shall refer to the different figures expressed in IEC/TS 62257-2, Annex C.
The control system of the generator set shall be able to provide information necessary to
assess that the level of quality of service provided is in accordance with the requirements of
the GS (at least voltage, current and frequency).
5.2.2 Generator set sizing
Generator set sizing has two primary requirements:
a) that the alternator is capable of supplying the continuous and surge load apparent power
(VA);
b) that the engine is capable of providing the power requirements of the alternator and the
mechanical losses of the whole system (alternator + coupling system).
It is for the project developer to precisely define the generator set minimum operating
conditions:
• the environmental conditions;
• the maximum nominal outputs, the corresponding durations and load factor;
• the electrical load characteristics (power factor, permitted voltage range, current harmonic
content, high starting currents, etc.).
The selection and sizing of generator set should be done with consideration of the supplied
electrical load and the structure of the microgrid (single phase / three phase, see
IEC/TS 62257-9-2).
TS 62257-7-3 © IEC:2008(E) – 13 –
Important rating of the generator set shall be considered:
• rated voltage;
• rated frequency;
• rated power and corresponding operating speed in conformity with ISO 8528-1;
• the application class, as defined in ISO 8528-1, Clause 7) (see Annex A);
• rated current;
• rated power factor.
NOTE When considering the power rating it is important to consider the application Class and the service to be
provided. Refer to ANNEX A.
Care needs to be taken with respect to application classes defined in ISO 8528-1 as these
classes of operation take into account only predominantly linear loads. In many microgrid and
hybrid system applications, considerable harmonic current flows (particularly in battery
charger loads) may cause excessive voltage distortion if not taken into account early in the
design and specification.
The sizing of the generator set shall be made such as the engine works between 50 % and
80 % of its maximum nominal power in normal operating conditions. Functioning at maximum
nominal power shall not exceed manufacturer’s recommendations as well as overload periods
of functioning.
The project implementer shall draw the daily load curve and its variation along the year in
order to determine the maximum and minimum power. This makes it possible to determine the
nominal power of the engine to ensure that it operates between 50 % and 80 % of its
maximum nominal power.
The project implementer shall also assess if there is any peak power or very low power period
during the year which duration may affect the generator set lifespan. A solution could be to
install two generator sets:
– a main generator set;
– a secondary generator set.
In this configuration, if there is a peak period, it is possible to use the secondary generator set
in order to provide the additional necessary power. This second generator set shall be sized
according to this additional necessary power. In the same way, if there is a low power period,
the secondary generator set can be used.
Local conditions shall be taken into account to size the generator set (altitude, humidity,
temperature, etc.) according to 5.2.3.
The local conditions shall be checked by the project developer and indicated in the call for
tender to manufacturers.
Technical declarations for the specification and design of the generator sets recommended by
ISO 8528-7 are to be carried out as follows:
– the project implementer expresses his requirements in a technical questionnaire in
conformity with Annex A of ISO 8528-7;
– the specifications approved by the generator set manufacturer and the project
implementer shall be set out in a technical form as per Annex C of ISO 8528-7.

– 14 – TS 62257-7-3 © IEC:2008(E)
5.2.3 Generator set type
There are different kinds of generator sets available on the market. Annex A gives the main
guidelines to choose the right type of generator set according to the type of use which is
expected, in conformity with ISO 8528-1:
– indoor or outdoor use;
– service duration;
– noise level;
– etc.
5.2.4 Derating factors
The site conditions under which the generator set is called upon to operate, whatever be its
mode of installation, may affect certain of its characteristics. They shall be taken into account
by the project implementer and the manufacturer.
When the site conditions are unknown and unless otherwise specified, the following nominal
conditions shall be used according to ISO 8528-1.
– total barometric pressure 89,9 kPa;
– air temperature 25 °C;
– relative humidity 30 %;
– temperature coolant for the supercharging air 25 °C.
As the generator set magnitudes are usually defined for the standard reference conditions, it
is therefore necessary to clearly define and to take into account climatic conditions at the
intended site.
The generator set shall be rated to operate over:
– the range of expected temperatures, and
– humidity conditions, and
– altitude prevailing at the application site.
Table 1 provides some examples of derating factors taking into account local conditions.
Table 1 – Examples of derating factors for generator sets
Air temperature Derate 2,5 % for every 5 °C above 25 °C
Altitude Derate 3 % for every additional 300 m above 300 m altitude
Air temperature
between 30 °C and Derate 0,5 % for every 10 % above 60 % humidity
40 °C
Air temperature
Humidity
Derate 1,0 % for every 10 % above 60 % humidity
between 40 °C and
50 °C
Air temperature
Derate 1,5 % for every 10 % above 60 % humidity
above 50 °C
NOTE when performing genset sizing calculations, the derating factors should be added to the required size
specification.
In particular, it should be noted that beyond the reference conditions (temperature 25 °C and
pressure < 89,9 kPa) engine power oversizing should be considered. Special attention shall
be paid to the cooling system in relation with the environmental conditions.

TS 62257-7-3 © IEC:2008(E) – 15 –
5.2.5 Starting system
The GS shall define the starting system of the generator set: manual or automatic, remote or
not. The choice of the starting system impacts the design of the generator set site and the
operating conditions.
The starting battery shall be installed as close as possible to the engine. The cables shall be
sized according to the starting current but also according to the distance between the battery
and the engine.
Where the generator set is seldom used (back-up systems) attention shall be paid that the
starting battery is kept at an acceptable state of charge.
5.2.6 Control systems
The GS shall define the parameters to be surveyed during operation; voltage, frequency,
output power, temperature of air, water, engine, etc.
Frequency and voltage adjustments can be either automatic or manual. This shall be defined
by the GS.
5.2.7 Noise issues
The generator set shall be rated appropriately taking into consideration the noise level
produced under worst case operating conditions.
The generator sets shall be in conformity, with regard to noise emitted, with the airborne
noise level limits as set out in Table 2.
Table 2 – Generator set permitted noise levels
Generator electrical output Permitted noise level
P dBA
P ≤ 2 kVA 102
2 kVA < P < 240 kVA
Compliance with these limits may require the use of a soundproofing casing.
The generator set alternator noise levels shall be in conformity with IEC 60034-9, depending
on its cooling methods and its rated rotation speed.
5.2.8 Environmental issues
The project implementer shall inform the manufacturer of the environmental conditions that
may affect the design and maintenance of the generator set:
– presence of sand, dust or other physical pollutants of the atmosphere of the generator set;
– marine environment (generator set operating on costal sites);
– shock and vibrations (earth tremors, presence of another rotating machine, etc.);
– presence of chemical pollution.
5.3 Erection
5.3.1 Shipping
Shipping to the site, installation and commissioning of the generator set are carried out in
conformity with the generator set supplier's recommendations.

– 16 – TS 62257-7-3 © IEC:2008(E)
Access and transport to the site shall be taken into consideration:
– quality of roads;
– maximum size for trucks;
– local available handling devices;
– on-board-the-truck handling devices.
Attention shall be paid to the fact that it is sometimes necessary to move the generator set to
another site when heavy maintenance is required. It is thus sometimes more efficient to install
several smaller generator sets than a single large generator set.
Before handling, the attachment points and handling devices shall be inspected to ensure that
they are adequate for the weight and size of the generator set to be handled. Built-in
attachment points and handling gear of the generator set shall be used wherever possible for
this purpose.
Position and angle of slings shall conform to correct handling rules. Special attention shall be
paid to the condition of the slings.
5.3.2 Design of the erection site
5.3.2.1 General
The generator set can be installed either in the open air or in a dedicated building.
In case of use as an individual electrification system (see IEC/TS 62257-2), the generator set
shall be installed outside the house.
In all situations the floor of the site shall allow the generator sets to be restrained from
movement during normal operation.
5.3.2.2 Civil works (if any)
The civil works may be conventional masonry work, or pre-fabricated. Its lifespan shall be at
least equal to the generator set lifespan.
– The floor shall be able to bear the weight of the generator set and its accessories.
– Provision shall be made to avoid any pollution of the soil by oil or fuel leaks.
– It shall enable easy installation and removal of the equipment.
– The wiring trays (cables) and mechanical trays (fluids) shall be separate.
– Metal frameworks shall be connected to the earth.
– A water supply point and drain shall be provided if necessary.
– The genset premises shall not be used for storage of fuel or spare parts.
5.3.2.3 Safety provisions
5.3.2.3.1 Access space for generator sets
Adequate space shall be provided around a generator set on all sides where persons are to
pass, to enable all equipment to be safely and effectively operated and adjusted.
NOTE Attention is drawn to additional requirements that may be specified by relevant regulatory authorities.
5.3.2.3.2 Setting up of the generator set
All generator sets shall be restrained from movement during normal operation.

TS 62257-7-3 © IEC:2008(E) – 17 –
5.3.2.3.3 Automatic starting
Where a generator set is capable of automatic or remote manual starting, a warning notice
shall be clearly visible on approach to, and located within 1 m of the generator set, bearing
the words “danger; this equipment starts automatically”. The generator engine shall be
provided with a device to prevent the starting of the generator when inspection, repair or
maintenance is carried out.
5.3.2.3.4 Exit from generator set area
5.3.2.3.4.1 Number of opening
At least one door or opening shall be provided to enable a person to leave the vicinity of
a generator set. However, where any generator set
a) has a rated power exceeding 25 kVA; or
b) is driven by a petrol engine;
not less than two opening generator set or doorways, spaced well apart, shall be provided.
5.3.2.3.4.2 Opening and locking of doors
All barriers or doors provided to prevent the entry of unauthorized persons to any room
or enclosure containing a generator set shall open outwards away from the generator
set without the use of a key or tool on the generator set side of the door, and shall be capable
of being locked from the outside.
5.3.2.3.4.3 Size of doors and opening
Doors and opening providing entrance to and exit from a generator set area shall have
a height of not less than 1,98 m from the floor or walked-on surface and a width of not
less than 0,75 m.
5.3.2.3.5 Lighting
Adequate lighting shall be provided to enable equipment and controls to be effectively
and safely operated.
5.3.2.3.6 Earthing
The earth connection shall be in conformity with the requirements of IEC/TS 62257-5.
All metal assemblies are to be connected to the installation earthing terminal:
– the generator set;
– its cabinet, if any;
– the tanks and piping;
– the cable trays, metal roof decking;
– hardware.
5.3.3 Installation requirements
5.3.3.1 General
Means shall be provided to prevent the entrance of, or interference by, unauthorized (see
IEC/TS 62257-6) persons by the erection of suitable fences, screens, partitions, walls or
similar barriers. Such barriers shall not impede the access required for authorized persons for
maintenance, testing or inspection.

– 18 – TS 62257-7-3 © IEC:2008(E)
This shall not preclude the installation of a generator set in an enclosure or room with other
equipment for which access is similarly restricted to authorized persons.
5.3.3.2 Ventilation
Ventilation shall be as far as possible from the gas exhaust of the engine, especially the fresh
air admission. The extraction of hot air shall be made through the upper ventilation and the
fresh air admission through the lower one.
Ventilation grates shall be kept clean.
For a generator set installed in an enclosed and soundproofed room, the room should enable
proper supply to the engine of combustion and cooling air and also maintain the generator set
within the ambient temperature limits for which it was specified.
The generator set air consumption is notified by the manufacturer. If not, the following values
may be used as a reference.
The air intake cross-section shall be the same as that of delivery and determined as follows:
– radiator or air cooler 80 m /h per kVA,
– additional fan 40 m /h per kVA,
–1
– speed in ducting 4 m s ,
3 3 –1
EXAMPLE Generator set of 30 kVA: flow 30 × 80 = 2 400 m /h = 0,67 m s ,
3 –1 –1 2
cross-section = 0,67 m s / 4 m s = 0,17 m .
Ventilation of the generator set installation room shall be dimensioned in order to comply with
the limit ambient temperatures permitted by the generator set, engine and alternator, under
the specified operating and environment conditions.
For this, the generator set supplier shall provide
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