IEC 61892-3:2007

IEC 61892-3
Edition 2.0 2007-11
INTERNATIONAL
STANDARD
Mobile and fixed offshore units – Electrical installations –
Part 3: Equipment
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IEC 61892-3
Edition 2.0 2007-11
INTERNATIONAL
STANDARD
Mobile and fixed offshore units – Electrical installations –
Part 3: Equipment
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XA
ICS 47.020.60 ISBN 2-8318-9391-7

– 2 – 61892-3 © IEC:2007(E)
CONTENTS
FOREWORD.5
INTRODUCTION.7

1 Scope.8
2 Normative references .8
3 Terms and definitions .10
4 General requirements .13
4.1 Degree of protection.13
4.2 Service conditions .13
4.3 Temperature rise.13
4.4 Nameplates and labels .13
5 Generators and motors.13
5.1 General .13
5.2 Voltage regulation of generators.14
5.3 Generators for special purposes.15
5.4 Parallel operation of general service generators – AC generators.15
5.5 Mechanical features (generators and motors).16
5.6 Lubrication (generators and motors) .17
5.7 Prime movers .17
5.8 Cyclic irregularity .17
5.9 Lubrication (prime movers).18
5.10 Running speed .18
5.11 Testing .18
6 Transformers for power and lighting .18
6.1 General .18
6.2 Winding arrangement .18
6.3 Terminals .19
6.4 Cooling arrangement .19
6.5 Voltage regulation .19
6.6 Parallel operation .19
6.7 Tests.20
7 Switchgear and controlgear assemblies.20
7.1 Service conditions .20
7.2 Definitions .20
7.3 Low-voltage switchgear and controlgear assemblies .20
7.4 Switchgear and controlgear in the range above 1 kV up to and including

35 kV .25
7.5 Instruments for assemblies.26
8 Semiconductor convertors .28
8.1 General .28
8.2 Internal wiring .28
8.3 Cooling arrangements .28
8.4 Accessibility .28
8.5 Service conditions .29
8.6 Application .29
8.7 Diagrams.29

61892-3 © IEC:2007(E) – 3 –
8.8 Convertor transformers.29
9 Secondary cells and batteries.30
9.1 General .30
9.2 Types of batteries.30
9.3 Charging facilities.30
9.4 Ventilation of secondary battery compartments .30
10 Luminaires .31
10.1 General .31
10.2 Construction.31
10.3 Temperature and temperature rise .31
10.4 Exposure to mechanical damage .31
10.5 Discharge lamp luminaires operating at voltages below 250 V.31
10.6 Discharge lamp luminaires operating at voltages above 250 V .32
10.7 Searchlights and arc lamps .32
10.8 Portable luminaires .32
11 Heating and cooking appliances .33
11.1 General .33
11.2 General requirements.33
11.3 Special requirements for galley appliances.35
11.4 Special requirements for space-heating appliances .35
12 Trace and surface heating .35
12.1 General .35
12.2 Construction.36
13 Communication.36
13.1 General .36
13.2 Safety requirements .36
13.3 External communication systems.36
13.4 Internal communication .36
13.5 Safety and maintenance .37
14 Underwater systems and appliances.37
14.1 General .37
14.2 Fixed diving systems .38
14.3 Temporary diving systems.38
15 Control and instrumentation.38
15.1 General .38
15.2 General requirements .38
15.3 Environmental and supply conditions and testing.38
15.4 Adjustments .46
15.5 Accessibility .46
15.6 Replacement .46
15.7 Non-interchangeability.46
15.8 Cooling air.47
15.9 Mechanical load on connectors.47
15.10 Mechanical features of cabinets .47
15.11 Shock and vibration absorbers .47
15.12 Internal wiring.47
15.13 Cable connections .47
15.14 Rodent protection .47

– 4 – 61892-3 © IEC:2007(E)
15.15 Sensors.47
15.16 Computer-based systems .48
16 Accessories.51
16.1 General .51
16.2 Enclosures .51
16.3 Switches .51
16.4 Socket outlets and plugs .51

Annex A (informative) Alternative method of power generation .53

Bibliography.59

Figure A.1 – PV Power generating system – Major functional elements, sub-systems
and power flow diagram .54
Figure A.2 – Power generating system – Major functional elements .55
Figure A.3 – CCVT Operating principle block diagram.57
Figure A.4 – Micro turbine Typical block diagram .58

Table 1 – Limits of cyclic irregularity .18
Table 2 – Clearance and creepage distances for non type-tested assemblies .22
Table 3 – Temperature limits of exposed parts.34
Table 4 – Type tests, test procedures and severities.40

61892-3 © IEC:2007(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MOBILE AND FIXED OFFSHORE UNITS –
ELECTRICAL INSTALLATIONS –
Part 3: Equipment
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.
International Standard IEC 61892-3 has been prepared by IEC technical committee 18:
Electrical installations of ships and of mobile and fixed offshore units.
This second edition cancels and replaces the first edition published in 1999. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the requirement to d.c. generators has been deleted;
b) detailed requirements to testing of machines have been deleted. Reference is made to the
IEC 60034 series;
c) requirement to switchgear and controlgear has been rewritten, based on updated
IEC 60439 and the IEC 62271 series;
d) requirement to Control and instrumentation has been rewritten, based on updated
IEC 60092-504.
– 6 – 61892-3 © IEC:2007(E)
The text of this standard is based on the following documents:
FDIS Report on voting
18/1064/FDIS 18/1070/RVD
Full information on the voting for the approval of this standard 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 the IEC 61892 series, under the general title Mobile and fixed offshore
units – Electrical installations, 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
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

61892-3 © IEC:2007(E) – 7 –
INTRODUCTION
IEC 61892 forms a series of International Standards intended to enable safety in the design,
selection, installation, maintenance and use of electrical equipment for the generation,
storage, distribution and utilisation of electrical energy for all purposes in offshore units which
are being used for the purpose of exploration or exploitation of petroleum resources.
This part of IEC 61892 also incorporates and co-ordinates, as far as possible, existing rules
and forms a code of interpretation, where applicable, of the requirements of the International
Maritime Organisation, a guide for future regulations which may be prepared and a statement
of practice for offshore unit owners, constructors and appropriate organisations.
This standard is based on equipment and practices which are in current use but it is not
intended in any way to impede development of new or improved techniques.
The ultimate aim has been to produce a set of International Standards exclusively for the
offshore petroleum industry.
– 8 – 61892-3 © IEC:2007(E)
MOBILE AND FIXED OFFSHORE UNITS –
ELECTRICAL INSTALLATIONS –
Part 3: Equipment
1 Scope
This part of IEC 61892 contains provisions for electrical equipment in mobile and fixed
offshore units including pipeline, pumping or 'pigging' stations, compressor stations and
exposed location single buoy moorings, used in the offshore petroleum industry for drilling,
processing and for storage purposes.
This standard applies to equipment in all installations, whether permanent, temporary,
transportable or hand-held, to a.c. installations up to and including 35 000 V and d.c.
installations up to and including 750 V (a.c. and d.c. voltages are nominal values).
This standard gives requirements to equipment, which is additional to the requirement given
in the product standard for the relevant equipment.
This standard does not apply to the electrical installations in rooms used for medical purposes
or in tankers.
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.
CISPR 16 (all parts), Specification for radio disturbance and immunity measuring apparatus
and methods
IEC 60034 (all parts), Rotating electrical machines
IEC 60044-1:1996, Instrument transformers – Part 1: Current transformers
IEC 60044-2:1997, Instrument transformers – Part 2: Inductive voltage transformers
IEC 60065:2001, Audio, video and similar electronic apparatus – Safety requirements
IEC 60068 (all parts) Environmental testing
IEC 60076 (all parts), Power transformers
IEC 60076-1:2000, Power transformers – Part 1: General
IEC 60076-5:2006, Power transformers – Part 5: Ability to withstand short circuit
IEC 60076-11:2004, Power transformers – Part 11: Dry-type transformers
IEC 60092 (all parts), Electrical installations in ships
IEC 60146-1-1:1991, Semiconductor converters – General requirements and line commutated
convertors – Part 1-1: Specifications of basic requirements
IEC 60146-1-2:1991, Semiconductor converters – General requirements and line commutated
convertors – Part 1-2: Application guide
IEC 60146-1-3:1991, Semiconductor converters – General requirements and line commutated
convertors – Part 1-3: Transformers and reactors
IEC 60146-2:1999, Semiconductor converters – Part 2: Self-commutated semicondutor
converters including direct d.c. converters

61892-3 © IEC:2007(E) – 9 –
IEC 60282 (all parts), High-voltage fuses
IEC 60309 (all parts), Plugs, socket-outlets and couplers for industrial purposes
IEC 60331 (all parts), Tests for electric cables under fire conditions – Circuit integrity
IEC 60332-1-2:2004, Tests on electric and optical fibre cables under fire conditions –
Part 1-2: Test for vertical flame propagation for a single insulated wire or cable – Procedure
for 1 kW premixed flame
IEC 60439 (all parts), Low-voltage switchgear and controlgear assemblies
IEC 60439-1:2004, Low-voltage switchgear and controlgear assemblies – Part 1: Type-tested
and partially type-tested assemblies
IEC 60529:2001, Degrees of protection provided by enclosures (IP Code)
IEC 60533:1999, Electromagnetic compatibility – Electrical and electronic installations in
ships
IEC 60865-1:1993, Short-circuit currents – Calculation of effects – Part 1: Definitions and
calculation methods
IEC 60884 (all parts), Plugs and socket-outlets for household and similar purposes
IEC 60896-11:2002, Stationary lead-acid batteries – Part 11: Vented types – General
requirements and methods of tests
IEC 60896-21:2004, Stationary lead-acid batteries – Part 21: Valve regulated types – Methods
of test
IEC 60896-22:2004, Stationary lead-acid batteries – Part 22: Valve regulated types –
Requirements
IEC 60906 (all parts), IEC system of plugs and socket-outlets for household and similar purposes
IEC 60945:2002, Maritime navigation and radiocommunication equipment and systems – General
requirements – Methods of testing and required test results
IEC 60947-3:1999, Low-voltage switchgear and controlgear – Part 3: Switches, disconnectors,
switch-disconnectors and fuse-combination units
IEC 61000-4-2:1995, Electromagnetic compatibility (EMC) – Part 4-2: Testing and measurement
techniques – Electrostatic discharge immunity test
IEC 61000-4-3:2006, Electromagnetic compatibility (EMC) – Part 4-3: Testing and measurement
techniques – Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4:2004, Electromagnetic compatibility (EMC) – Part 4-4: Testing and measurement
techniques – Electrical fast transient/burst immunity test
IEC 61000-4-5:2005, Electromagnetic compatibility (EMC) – Part 4-5: Testing and measurement
techniques – Surge immunity test
IEC 61000-4-6:2003, Electromagnetic compatibility (EMC) – Part 4-6: Testing and measurement
techniques – Immunity to conducted disturbances, induced by radio-frequency fields
IEC 61000-4-11:2004, Electromagnetic compatibility (EMC) – Part 4-11: Testing and measurement
techniques – Voltage dips, short interruptions and voltage variations immunuty tests
IEC 61097 (all parts), Global maritime distress and safety system (GMDSS)
IEC 61131 (all parts), Programmable controllers
___________
A consolidated edition (1.2), published in 2001, exists including IEC 61000-4-2 (1995), its Amendment 1 (1998)
and its Amendment 2 (2000).
A consolidated edition (2.2), published in 2006, exists including IEC 61000-4-2 (2003), its Amendment 1 (2004)
and its Amendment 2 (2005).
– 10 – 61892-3 © IEC:2007(E)
IEC 61800 (all parts), Adjustable speed electrical power drive systems
IEC 61892-1, Mobile and fixed offshore units – Electrical installations – Part 1: General
requirements and conditions
IEC 61892-2, Mobile and fixed offshore units – Electrical installations – Part 2: System design
IEC 61892-4, Mobile and fixed offshore units – Electrical installations – Part 4: Cables
IEC 61892-5, Mobile and fixed offshore units – Electrical installations – Part 5: Mobile units
IEC 61892-6, Mobile and fixed offshore units – Electrical installations – Part 6: Installation
IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous
areas
IEC 62040 (all parts), Uninterruptible power systems (UPS)
IEC 62271 (all parts), High-voltage switchgear and controlgear
IEC 62271-100:2001, High-voltage switchgear and controlgear – Part 100: High-voltage
alternating-current circuit-breakers
IEC 62271-102:2005, High-voltage switchgear and controlgear – Part 102: Alternating-current
disconnectors and earthing switches
IEC 62271-200:2003, High-voltage switchgear and controlgear – Part 200: AC metal-enclosed
switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV
IEC 62271-201, High-voltage switchgear and controlgear – Part 201: AC insulation-enclosed
switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV
ISO 6592:2000, Information technology – Guidelines for the documentation of computer-
based application systems
IMO Code of Safety for Diving Systems
3 Terms and definitions
For the purposes of this document the terms and definitions given in IEC 61892-1 through
IEC 61892-7 and the following apply:
3.1
appropriate authority
governmental body and/or classification society with whose rules a unit is required to comply
3.2
computer-based system
system that consists of one or more programmable electronic devices with the connections,
peripherals and software necessary to automatically carry out specified functions
NOTE The following types of programmable devices could form part of a computer system: mainframe, mini-
computer, micro-computer, programmable logic controller.
3.3
convertor
a set of equipment, static or rotating, to convert one type of electric current to another type,
different in nature, voltage and/or frequency
3.4
distribution board
switchgear or controlgear assembly for the control and distribution of electrical power to final
subcircuits
3.5
double insulation
insulation comprising both basic insulation and supplementary insulation

61892-3 © IEC:2007(E) – 11 –
3.6
electric surface heating
heat generated in the surface layer of a body to be heated by electrical means in order to
raise or maintain its temperature
3.7
electric surface heating device
resistive or skin effect device designed to produce a defined output at a declared voltage and
temperature, and terminated in a manner suitable for connection to the electricity supply
3.8
electric surface heating systems
system of electric surface heating devices together with any controls, thermal insulation and
protective cladding designed to meet a specified electric surface heating requirement
3.9
electromagnetic compatibility EMC
ability of an equipment or system to function satisfactorily in its electromagnetic environment
without introducing intolerable electromagnetic disturbances to anything in that environment
3.10
emergency switchboard
switchgear and controlgear assembly which is normally supplied by the main switchboard but
which, in the event of failure of the main electrical power supply system, is directly supplied
by the emergency source of electrical power or the transitional source of emergency power
and is intended to distribute and control electrical energy to the emergency services for all
electrical consumers essential to the safety of the crew, contractors, visitors and the unit
under emergency conditions
3.11
expert system
intelligent knowledge-based system that is designed to solve a problem using information that
has been compiled from some form of human expertise
3.12
extra-low voltage ELV
voltage which does not exceed 50 V a.c. r.m.s. between conductors, or between any
conductor and earth, in a circuit isolated from the supply by means such as safety isolating
transformers, or convertors with separate windings; a voltage which does not exceed 50 V
d.c. between conductors, or between any conductor and earth, in a circuit which is isolated
from higher voltage circuits.
NOTE 1 Consideration should be given to the reduction of the limit of 50 V under certain conditions, such as wet
surroundings, exposure to heavy seas or powerful water jets where direct contact with live parts is involved.
NOTE 2 The voltage limit should not be exceeded, either at full load or no load, but it is assumed, for the purpose
of this definition, that any transformer or convertor is operated at its rated supply voltage.
NOTE 3 Information about protection by extra-low voltage is given in IEC 60364-4-41.
3.13
heating cable
cable, with or without a shield or a metallic sheath, intended to give off heat for heating
purposes
3.14
invertor
convertor for conversion from d.c. to a.c.
3.15
low-voltage switchgear and controlgear assemblies
combination of one or more low-voltage switching devices together with associated control,
measuring, signalling, protective, regulation equipment, etc., completely assembled under the
responsibility of the manufacturer with all the internal electrical and mechanical inter-
connections and structural parts

– 12 – 61892-3 © IEC:2007(E)
3.16
main switchboard
switchgear and controlgear assembly which is directly supplied by the main source of
electrical power and is intended to distribute and control electrical energy to the unit’s
services
3.17
non-type-tested low-voltage switchgear and controlgear assemblies NTTA
low-voltage switchgear and controlgear assembly which does not belong to 3.18 or 3.27
3.18
partially type-tested low-voltage switchgear and controlgear assemblies PTTA
low-voltage switchgear and controlgear assembly, containing both type-tested and non-type-
tested arrangements provided that the latter are derived (e.g. by calculation) from type-tested
arrangements which have complied with the relevant tests
3.19
rectifier
convertor for conversion of a.c. to d.c.
3.20
reinforced insulation
single insulation system applied to live parts, which provides a degree of protection against
electric shock equivalent to double insulation under the conditions specified in the relevant
IEC standard
NOTE The term ”insulation system” does not imply that the insulation must be one homogeneous piece. It may
comprise several layers which cannot be tested singly as supplementary or basic insulation
3.21
resistive device
electric surface heating device of either the trace heating unit type or the surface heating unit type
3.22
(secondary) cell (Syn. (rechargeable) cell)
an assembly of electrodes and electrolyte which constitutes the basic unit of a secondary battery
3.23
section boards
switchgear and controlgear assembly for controlling and distributing the supply of electrical
power to other section boards, distribution boards or final subcircuits
3.24
semiconductor device
device whose essential characteristics are due to the flow of charge carriers within a semi-
conductor
3.25
skin effect device
electric surface heating device of the skin effect heater type
3.26
software
program, procedures and associated documentation pertaining to the operation of a computer
system and including both the application (user) program and the operating system (firmware)
program
3.27
type-tested low-voltage switchgear and controlgear assembly TTA
low-voltage switchgear and controlgear assembly conforming to an established type or system
without deviations likely to significantly influence the performance from the typical assembly
verified to be in accordance with this standard

61892-3 © IEC:2007(E) – 13 –
3.28
valve-regulated battery cell
a secondary cell which is closed under normal conditions but which has an arrangement
which allows the escape of gas if the internal pressure exceeds a predetermined value. The
cell cannot normally receive addition to the electrolyte
3.29
vented (secondary) battery cell (Syn. open (secondary) cell)
a secondary cell having a cover provided with an opening through which gaseous products
may escape
NOTE The opening may be fitted with a venting system.
3.30
gastight sealed (secondary) cell
a secondary cell which remains closed and does not release either gas or liquid when
operated within the limits and temperature specified by the manufacturer. The cell may be
equipped with a safety device to prevent dangerously high internal pressure. The cell does
not require addition to the electrolyte and is designed to operate during its life in its original
sealed state
4 General requirements
4.1 Degree of protection
Degree of protection for electrical equipment shall be as specified in IEC 61892-2.
4.2 Service conditions
The normal environmental conditions shall be as stated in IEC 61892-1. Other environmental
conditions shall be agreed between the manufacturer and the user if required, for example for
use in arctic or tropical climates.
4.3 Temperature rise
Temperature rise shall be in accordance with the relevant product standard, taking into
consideration the ambient temperatures referred to in IEC 61892-1.
NOTE When a rotating machine is connected to a supply system with harmonic distortion, the rating of the
machine must allow for the increased heating effect of the harmonic loading.
4.4 Nameplates and labels
Each unit and main subassembly shall have nameplates clearly and indelibly marked with
the data specified in the appropriate IEC standard.
Warning labels shall be provided in all location where necessary to warn personal of
potentially dangerous situations.
All nameplates and labels shall be engraved on plastic-laminated material and secured with
non-corrodible screws or rivets. Adhesive or self-tapping screws are unacceptable.
5 Generators and motors
5.1 General
The provisions of this clause are applicable to all rotating machines rated at 750 W or more
for use in offshore units. It also applies to excitation machines and includes relevant
requirements for prime-mover driving generators. Requirements particular to electrical
propulsion machines are given in IEC 61892-5.
All electrical machines shall comply with the relevant requirements of IEC 60034-1 and also
with the additional requirements included in this standard.
The duty types shall be in accordance with 60034-1.
When the duty is not declared, the manufacturer shall assume that duty shall be type S1
(continuous running duty) for generators and motors.

– 14 – 61892-3 © IEC:2007(E)
5.2 Voltage regulation of generators
5.2.1 General
The inherent voltage regulation of a general service generator shall be designed in relation to
the speed regulation and governing of the prime movers as outlined below.
NOTE "General service" means that supplying motors and other consumers are a part of the normal distribution
system of the unit. Consumers such as propulsion motors and other special consumers, for which other governing
characteristics can be accepted or are required, are not considered part of the general service.
5.2.2 DC generators
The use of standard pattern of DC generators in mobile and fixed offshore unit is very limited,
general reference is made to the 60092 series.
5.2.3 AC generators
The excitation system of a.c. generators rated 50 kW and above, and complying with 5.5,
shall also comply with the requirements given below.
5.2.3.1 Steady conditions: tolerance of voltage and waveform
Each a.c. generator for general service driven by its prime-mover, whose governor charac-
teristics comply with 5.8.2, shall be provided with an excitation system capable of maintaining
the voltage under steady conditions within ±2,5 % of the rated voltage for all loads between
zero and rated load at the rated power factor. These limits may be increased to ±3,5 % for
emergency sets (see 5.2.3.4).
When the generator is driven at rated speed, giving its rated voltage and rated symmetrical
load, the tolerance of waveform shall not exceed the values listed below:
• total harmonic distortion: 5 %
• single harmonic: 3 %
NOTE Attention is drawn to the possibility that under certain operating conditions the power factor may be less
than the rated value, and that this can affect the voltage regulation.
5.2.3.2 Transient conditions
When the generator is driven at rated speed, giving its rated voltage, and is subject to a
sudden change of symmetrical load within the limits of a specified current and power factor,
the voltage shall not fall below 80 % nor exceed 120 % of the rated voltage.
The voltage of the generator shall then be restored to within ±3 % of the rated voltage, for the
main generator set in not more than 1,5 s. For emergency sets these values may be
increased to ±4 % in not more than 5 s respectively (see 5.2.3.4).
In the absence of precise information concerning the maximum values of the sudden loads,
the following conditions shall be assumed: 60 % of the rated current with a power factor of
between 0,4 lagging and 0 to be thrown on with the generator running at no load, and then
withdrawn after steady-state conditions have been reached.
NOTE 1 Voltage regulation under transient conditions should be verified with all components as in normal
operation (e.g. prime mover, generator and voltage regulator).
NOTE 2 To achieve satisfactory performance on board a unit, the governor of the prime-mover must restore the
speed to a steady state within the limits specified in 5.8.2 in not more than 3 s.
5.2.3.3 Steady short-circuit conditions
Under short circuit conditions on the generator, it may be necessary to sustain a minimum
value of current (after the transient disturbance has ceased ) for a sufficient time to ensure
operation of the system’s protecting devices. Sustained short circuit current is attained by an
excitation system designed to provide a specific value of short circuit current. The value of
sustained short circuit current shall be decided in agreement between purchaser and
manufacturer.
61892-3 © IEC:2007(E) – 15 –
NOTE 1 For instance a current of at least three times its rated value for a duration of up to 2 s, unless protection
selectivity conditions exist which allow a shorter duration and provided that, in any case, the safety of the
installation is ensured, is acceptable.
NOTE 2 Sustained short circuit current is not necessary in cases where special relaying or other designs or
means are employed to otherwise achieve selective protection.
5.2.3.4 Emergency generators
Emergency generator sets which are required to meet the same general requirements as in
5.2.3.2 need only maintain the steady-state voltage within 3,5 %, and during transient
conditions to recover their voltage within 4 % in not more than 5 s.
5.3 Generators for special purposes
5.3.1 DC generators
Special purpose d.c. generators, together with their excitation system, shall have such voltage
characteristics as are required.
5.3.2 AC generators
Special purpose a.c. generators and general service generators rated less than 50 kVA,
together with their excitation system, shall have the voltage characteristics agreed upon
between manufacturer and purchaser.
5.4 Parallel operation of general service generators – AC generators
5.4.1 Reactive load sharing
When a.c. generators are operated in parallel, the reactive load of the individual generating
sets shall not differ from their proportionate share of the total reactive load by more than 10 %
of the rated output of the largest machine, or more than 25 % of the smallest machine where
this v
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