IEC 61892-2:2012

Mobile and fixed offshore units - Electrical installations - Part 2: System design

IEC 61892-2:2012(E) contains provisions for system design of electrical installations in mobile and fixed units used in the offshore petroleum industry for drilling, production, processing and for storage purposes, including pipeline, pumping or 'pigging' stations, compressor stations and exposed location single buoy moorings. It applies to 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 1 500 V. (a.c. and d.c. voltages are nominal values). This standard does not apply either to fixed equipment used for medical purposes or to the electrical installations of tankers. This edition includes the following significant technical changes with respect to the previous edition:
- the d.c. voltage given in clause 1 has been updated to 1 500 V, to ensure consistency through all parts of the IEC 61892 series;
- Clause 4 has been rewritten, such that all requirements to emergency power are now given in 4.3;
- the tables for nominal a.c. voltages have been updated in accordance with the last revision of IEC 60038;
- the requirement to cross sectional area for earthing conductors has been made dependent on the system earthing arrangement;
- requirement for emergency stop for motor-driven fuel-oil transfer and fuel-oil pressure pumps has been added. The contents of the corrigendum of March 2013 have been included in this copy.

General Information

• Status: Published
• Publication Date: 14-Mar-2012
• ICS: 47.020.60 - Electrical equipment of ships and of marine structures
• Technical Committee: TC 18 - Electrical installations of ships and of mobile and fixed offshore units
• Drafting Committee: MT 18 - TC 18/MT 18
• Current Stage: DELPUB - Deleted Publication
• Start Date: 09-Apr-2019
• Completion Date: 26-Oct-2025

Relations

• Corrected By: IEC 61892-2:2012/COR1:2013 - Corrigendum 1 - Mobile and fixed offshore units - Electrical installations - Part 2: System design
• Effective Date: 05-Sep-2023
• Revised: IEC 61892-2:2019 - Mobile and fixed offshore units - Electrical installations - Part 2: System design
• Effective Date: 05-Sep-2023
• Revises: IEC 61892-2:2005 - Mobile and fixed offshore units - Electrical installations - Part 2: System design
• Effective Date: 05-Sep-2023

Overview

IEC 61892-2:2012 - "Mobile and fixed offshore units - Electrical installations - Part 2: System design" is an international standard for the system design of electrical installations on offshore petroleum units. It covers mobile and fixed units used for drilling, production, processing and storage, including pipeline/pumping (pigging) stations, compressor stations and exposed single buoy moorings. The standard applies to permanent, temporary, transportable and hand‑held installations for a.c. systems up to 35 000 V and d.c. systems up to 1 500 V (nominal). It excludes fixed medical equipment and the electrical installations of tankers.

Key topics and technical requirements

IEC 61892-2 focuses on practical system design elements for offshore electrical installations. Major technical topics include:

• Sources of electrical power - requirements for main and emergency power, starting arrangements for emergency generators and provisions for renewable sources (photovoltaic, eolic). (See Clause 4; emergency power consolidated in Clause 4.3.)
• System earthing - neutral earthing methods, earthing for systems up to/above 1 000 V, earthing resistors and connection to the hull/structure. (Clause 5)
• Distribution systems - AC and DC distribution topologies (TN, IT), DC system types, specified AC/DC voltages and control voltages. (Clause 6)
• Distribution design requirements - final circuits, lighting circuits, socket‑outlets, shore connections, motor circuits and starting arrangements. (Clause 7)
• Load modelling and studies - load/demand factors, load flow, short‑circuit, protection coordination and harmonic/power quality studies. (Clauses 8–9)
• Protection - selection and coordination of protective devices, generator/transformer/motor protection, undervoltage/overvoltage measures and rated breaking/making capacities. (Clause 10)
• Lighting and emergency lighting - general, emergency and escape lighting, navigation/obstruction signals and luminaires. (Clause 11)
• Control and instrumentation - safety, segregation, EMC, monitoring and design for safety‑critical and fire/gas protection control systems. (Clause 12)

Notable technical updates in this edition: d.c. voltage updated to 1 500 V for series consistency; nominal a.c. volt tables aligned with IEC 60038; earthing conductor cross‑sectional requirements depend on earthing arrangement; emergency stop requirement added for motor‑driven fuel‑oil pumps.

Practical applications and who uses it

IEC 61892-2 is used by:

• Offshore electrical and systems engineers designing platform and floater distribution systems
• EPCI contractors and integrators responsible for power system layouts and protection coordination
• Asset owners/operators planning upgrades, shore connections and emergency power schemes
• Classification societies and regulatory authorities reviewing compliance for offshore units
• Control, instrumentation and lighting designers ensuring EMC, safety and emergency requirements

Typical applications: design of power generation and distribution on drilling rigs, FPSOs, production platforms, compressor/pumping stations and single buoy moorings.

Related standards

• IEC 61892 series (other parts covering installation, selection of equipment and verification)
• IEC 60038 (standard voltages) - used to align nominal a.c. voltage tables

Keywords: IEC 61892-2, offshore electrical installations, system design, mobile and fixed offshore units, emergency power, system earthing, distribution systems, offshore petroleum industry.

Standards Content (Sample)

IEC 61892-2 ®
Edition 2.0 2012-03
INTERNATIONAL
STANDARD
Mobile and fixed offshore units – Electrical installations –
Part 2: System design
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IEC 61892-2 ®
Edition 2.0 2012-03
INTERNATIONAL
STANDARD
Mobile and fixed offshore units – Electrical installations –

Part 2: System design
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 47.020.60 ISBN 978-2-88912-993-5

– 2 – 61892-2 © IEC:2012(E)
CONTENTS
FOREWORD . 7

INTRODUCTION . 9

1 Scope . 10

2 Normative references . 10

3 Terms and definitions . 11

4 Sources of electrical power . 16

4.1 General . 16
4.2 Main source of electrical power . 17
4.3 Emergency source of electrical power . 18
4.4 Starting arrangements for emergency generators . 21
4.5 Additional requirements for periodically unattended machinery spaces . 22
4.6 General requirements for renewable sources of electrical power . 22
4.6.1 Photovoltaic system . 22
4.6.2 Eolic system . 23
5 System earthing . 23
5.1 General . 23
5.2 General requirements . 23
5.3 Neutral earthing methods . 24
5.4 Neutral earthing for systems up to and including 1 000 V a.c. . 24
5.5 Neutral earthing for systems above 1 000 V . 25
5.6 Generators operated in parallel with source transformers . 25
5.7 Earthing resistors, connection to hull/structure . 25
6 Distribution systems . 27
6.1 DC distribution systems . 27
6.1.1 Types of distribution systems . 27
6.1.2 TN d.c. systems . 28
6.1.3 IT d.c. systems . 31
6.1.4 DC voltages . 31
6.2 AC distribution systems . 32
6.2.1 Primary a.c. distribution systems . 32
6.2.2 Secondary a.c. distribution systems . 32

6.2.3 TN a.c. systems . 32
6.2.4 IT a.c. systems . 34
6.2.5 AC voltages and frequencies . 34
6.2.6 Control voltage . 36
7 Distribution system requirements . 37
7.1 Earthed distribution systems . 37
7.2 Methods of distribution . 37
7.3 Balance of loads . 37
7.3.1 Balance of load on three-wire d.c. systems . 37
7.3.2 Balance of loads in three- or four-wire a.c. systems . 37
7.4 Final circuits . 37
7.4.1 General . 37
7.4.2 Final circuits for lighting . 37
7.4.3 Final circuit for lighting in accommodation spaces . 38

61892-2 © IEC:2012(E) – 3 –
7.4.4 Final circuits in offices and workshops . 38

7.4.5 Final circuits for heating . 38

7.5 Control circuits . 38

7.5.1 Supply systems and nominal voltages . 38

7.5.2 Circuit design . 38

7.5.3 Motor control . 38

7.5.4 Protection . 38

7.5.5 Arrangement of circuits . 39

7.6 Socket-outlets . 39

7.7 Shore connections for mobile units . 39

7.8 Motor circuits . 39
7.8.1 Starting of motors . 39
7.8.2 Means of disconnection . 40
7.8.3 Starters remote from motors . 40
7.8.4 Master-starter system . 40
8 Diversity (demand) factors . 40
8.1 Final circuits . 40
8.2 Circuits other than final circuits . 40
8.3 Application of diversity (demand) factors . 40
8.4 Motive power circuits – General . 40
9 System study and calculations . 41
9.1 General . 41
9.2 Electrical load study . 42
9.3 Load flow calculations . 42
9.4 Short-circuit calculations . 43
9.5 Protection and discrimination study . 44
9.6 Power system dynamic calculations. 45
9.7 Calculation of harmonic currents and voltages. 47
10 Protection . 47
10.1 General . 47
10.2 Characteristic and choice of protective devices with reference to short-circuit
rating . 48
10.2.1 General . 48
10.2.2 Protective devices . 48
10.2.3 Backup protection . 48

10.2.4 Rated short-circuit breaking capacity . 49
10.2.5 Rated short-circuit making capacity . 49
10.2.6 Co-ordinated choice of protective devices with regard to
discrimination requirements . 49
10.3 Choice of protective devices with reference to overload . 49
10.3.1 Mechanical switching devices . 49
10.3.2 Fuses for overload protection . 49
10.4 Choice of protective devices with regard to their application . 50
10.4.1 General . 50
10.4.2 Generator protection . 50
10.4.3 Protection of essential services . 51
10.4.4 Protection of transformers . 51
10.4.5 Circuit protection . 51
10.4.6 Motor protection . 51

– 4 – 61892-2 © IEC:2012(E)
10.4.7 Protection of lighting circuits . 52

10.4.8 Protection of power from external sources . 52

10.4.9 Secondary cells and battery protection . 52

10.4.10 Protection of meters, pilot lamps and control circuits . 52

10.4.11 Protection of static or solid state devices . 52

10.4.12 Protection for heat tracing systems . 53

10.5 Undervoltage protection . 53

10.5.1 Generators . 53

10.5.2 AC and DC motors . 53

10.6 Overvoltage protection . 53

10.6.1 General . 53
10.6.2 AC machines . 53
10.6.3 DC networks . 54
11 Lighting . 54
11.1 General . 54
11.2 General lighting system . 54
11.3 Emergency lighting system . 55
11.4 Escape lighting system . 56
11.5 Lighting circuits in machinery spaces, accommodation spaces, open deck
spaces, etc. . 57
11.6 Navigation and obstruction signals and lights . 58
11.7 Luminaires . 58
11.7.1 Discharge lamp luminaires of voltages above 250 V . 58
11.7.2 Searchlights . 58
12 Control and instrumentation . 58
12.1 Safeguarding . 58
12.2 Supply arrangement . 58
12.3 Dependability . 58
12.4 Safety . 59
12.5 Segregation . 59
12.6 Performance . 59
12.7 Integration . 59
12.8 Development activities . 59
12.9 Electromagnetic compatibility . 59
12.10 Design . 59

12.10.1 Environmental and supply conditions . 59
12.10.2 Circuit design . 60
12.10.3 Monitoring equipment . 60
12.10.4 Time delays . 60
12.10.5 Closed circuits . 60
12.10.6 Earth faults . 60
12.11 Installation and ergonomics . 60
12.11.1 General . 60
12.11.2 Remote controls . 60
12.12 Specific installations . 61
12.12.1 Safety critical systems . 61
12.12.2 Fire and gas protection control installations and other control
systems . 62
12.13 Automatic control installations for electrical power supply . 63

61892-2 © IEC:2012(E) – 5 –
12.13.1 General . 63

12.13.2 Automatic starting . 63

12.13.3 Automatic disconnection . 64

12.13.4 Automatic starting installations for electrical motor-driven
auxiliaries . 64

12.13.5 Manual control . 65

12.14 Machinery control installations . 65

12.14.1 General . 65

12.14.2 General requirement . 65

12.15 Public address and general alarm systems . 65

12.15.1 Audibility . 65
12.15.2 Operation . 65
12.15.3 Emergency broadcast . 65
12.15.4 Minimum sound level . 65
12.15.5 Fault tolerance . 65
12.15.6 Redundancy . 66
12.15.7 Segregation . 66
12.15.8 Power supplies . 66
12.15.9 Cabling . 66
12.16 Computer-based systems . 66
12.16.1 General . 66
12.16.2 System integration . 66
12.16.3 Power supply . 66
12.16.4 Data communication links . 67
12.16.5 Alarm, control and safety functions . 67
12.17 Software . 68
12.17.1 General . 68
12.17.2 Configuration . 68
12.17.3 Documentation . 69
12.18 Tests . 70
12.18.1 General . 70
12.18.2 Hardware . 70
12.18.3 Software . 71
12.18.4 System testing . 71
12.19 Documentation . 71

12.19.1 Apparatus description . 71
12.19.2 Circuit diagrams. 71
13 Degrees of protection by enclosures . 72
Annex A (informative) Variable a.c. speed drives . 76
Bibliography . 77

Figure 1 – Continuity of supply/continuity of service . 16
Figure 2 – TN-S d.c. system . 28
Figure 3 – TN-C d.c. system . 29
Figure 4 – TN-C-S d.c. system . 30
Figure 5 – IT d.c. system . 31
Figure 6 – TN-S a.c. system . 33
Figure 7 – TN-C-S a.c. system . 33

– 6 – 61892-2 © IEC:2012(E)
Figure 8 – TN-C a.c. system . 34

Figure 9 – IT a.c. system . 34

Figure A.1 – Typical a.c. drilling system . 76

Table 1 – Recommended maximum earth fault currents . 25

Table 2 – Summary of principal features of the neutral earthing methods . 26

Table 3 – Voltages for d.c. systems . 32

Table 4 – AC systems having a nominal voltage between 100 V and 1 000 V inclusive

and related equipment . 35

Table 5 – AC three-phase systems having a nominal voltage above 1 kV and not
a
exceeding 35 kV and related equipment . 36
Table 6 – General lighting illumination levels . 55
Table 7 – Recommended measuring points for measuring illumination in an area . 55
Table 8 – Escape lighting illumination levels . 56
Table 9 – Minimum requirements for the degree of protection for mobile and fixed
offshore units (Degree of protection as defined in IEC 61892-1) . 73

61892-2 © IEC:2012(E) – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
MOBILE AND FIXED OFFSHORE UNITS –

ELECTRICAL INSTALLATIONS –
Part 2: System design
FOREWORD
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International Standard IEC 61892-2 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 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• the d.c. voltage given in clause 1 has been updated to 1 500 V, to ensure consistency
through all parts of the IEC 61892 series;
• Clause 4 has been rewritten, such that all requirements to emergency power are now
given in 4.3;
• the tables for nominal a.c. voltages have been updated in accordance with the last
revision of IEC 60038;
– 8 – 61892-2 © IEC:2012(E)
the requirement to cross sectional area for earthing conductors has been made dependent

on the system earthing arrangement;

requirement for emergency stop for motor-driven fuel-oil transfer and fuel-oil pressure

pumps has been added.
The text of this standard is based on the following documents:

FDIS Report on voting
18/1240/FDIS 18/1255/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 the parts in 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 stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
The contents of the corrigendum of March 2013 have been included in this copy.

61892-2 © IEC:2012(E) – 9 –
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 (IMO), 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 the development of new or improved techniques.
The ultimate aim has been to produce a set of International standards exclusively for the
offshore petroleum industry.
– 10 – 61892-2 © IEC:2012(E)
MOBILE AND FIXED OFFSHORE UNITS –

ELECTRICAL INSTALLATIONS –
Part 2: System design
1 Scope
This part of IEC 61892 contains provisions for system design of electrical installations in
mobile and fixed units used in the offshore petroleum industry for drilling, production,
processing and for storage purposes, including pipeline, pumping or 'pigging' stations,
compressor stations and exposed location single buoy moorings.
It applies to 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
1 500 V. (a.c. and d.c. voltages are nominal values). This standard does not apply either to
fixed equipment used for medical purposes or to the electrical installations of tankers.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60038:2009, IEC standard voltages
IEC 60092-101:1994, Electrical installations in ships – Part 101: Definitions and general
requirements
IEC 60092-504:2001, Electrical installations in ships – Part 504: Special features – Control
and instrumentation
IEC 60447, Basic and safety principles for man-machine interface, marking and identification
– Actuating principles
IEC 60533, Electrical and electronic installations in ships – Electromagnetic compatibility

IEC 60909-0, Short-circuit currents in three-phase a.c. systems – Part 0: Calculation of
currents
IEC 60909-1, Short-circuit currents in three-phase a.c. systems – Part 1: Factors for the
calculation of short-circuit currents according to IEC 60909-0
IEC 60947-2:2006, Low-voltage switchgear and controlgear – Part 2: Circuit-breakers
IEC 61363-1, Electrical installations of ships and mobile and fixed offshore units – Part 1:
Procedures for calculating short-circuit currents in three-phase a.c.
IEC 61511 (all parts), Functional safety – Safety instrumented systems for the process
industry sector
61892-2 © IEC:2012(E) – 11 –
IEC 61660-1, Short-circuit currents in d.c. auxiliary installations in power plants and

substations – Part 1: Calculation of short-circuit currents

IEC 61892-1:2010, Mobile and fixed offshore units – Electrical installations – Part 1: General

requirements and conditions
IEC 61892-3:2007, Mobile and fixed offshore units – Electrical installations – Part 3:

Equipment
IEC 61892-5, Mobile and fixed offshore units – Electrical installations – Part 5: Mobile units

IEC 61892-7:2007, Mobile and fixed offshore units – Electrical installations – Part 7:
Hazardous areas
IEC 62271-100:2008, High-voltage switchgear and controlgear – Part 100: Alternating-current
circuit-breakers
SOLAS, International Convention for the Safety of Life at Sea
IMO MODU Code, Code for the Construction and Equipment of Mobile Offshore Drilling Units
IMO COLREG Code:1972, Convention on the International Regulations for Preventing
Collisions at Sea
IALA Recommendation O-1239:2008, On The Marking of Man-Made Offshore Structures
ICAO, International Civil Aviation Organization, Annex 14, Aerodromes
3 Terms and definitions
For the purposes of this document the terms and definitions given in IEC 61892-1 and the
following apply.
3.1 AC systems of distribution
3.1.1
single-phase two-wire a.c. system
system comprising two conductors only, between which the load is connected
Note 1 to entry In some countries this is designated as a two-phase system.

3.1.2
three-phase three-wire a.c. system
system comprising three conductors connected to a three-phase supply
3.1.3
three-phase four-wire a.c. system
system comprising four conductors of which three are connected to a three-phase supply and
the fourth to a neutral point in the source of supply
3.2
arc-flash hazard
a dangerous condition associated with the release of energy caused by an electric arc
[SOURCE: IEEE 1584:2002, 3.1]
– 12 – 61892-2 © IEC:2012(E)
3.3
availability
the state of an item of being able to perform its required function

[SOURCE: IEC 60050-603:1986, 603-05-04]

3.4
backup protection
protection which is intended to operate when a system fault is not cleared in due time
because of:
– failure or inability of a protective device closest to the fault to operate, or

– failure of a protective device, other than the protective device closest to the fault, to
operate
[SOURCE: IEC 60050-448:1995, 448-11-14, modified]
3.5
centralized control
control of all operations of a controlled system from one central control position
3.6
computer-based system
system that consists of one or more programmable electronic devices with their connections,
peripherals and software necessary to carry out automatically specified functions
3.7
continuity of service
condition, that after a fault in a circuit has been cleared, the supply to the healthy circuits is
re-established
Note 1 to entry See circuit 3 in Figure 1.
3.8
continuity of supply
condition that during and after a fault in a circuit, the supply to the healthy circuits is
permanently ensured
Note 1 to entry See circuit 3 in Figure 1.
3.9
control functions
functions intended to regulate the behaviour of equipment or systems

3.10
control position
control station
group of control devices by which an operator can control the performance of a machine,
apparatus, process or assembly of machines and apparatus
3.11 DC systems of distribution
3.11.1
two-wire d.c. system
system comprising two conductors only, between which the load is connected

61892-2 © IEC:2012(E) – 13 –
3.11.2
three-wire d.c. system
system comprising two conductors and a middle wire, the supply being taken from the two

outer conductors or from the middle wire and either outer conductor, the middle wire carrying

only the difference-current
3.12
diversity factor
demand factor
ratio of the estimated total load of a group of consumers under their normal working
conditions to the sum of their nominal ratings

3.13
fail-to-safe
principle by which a failure or malfunction of a component of the system causes its output to
automatically adjust to a predetermined safe state
[SOURCE: IEC 60050-191:1990, 191-15-04, modified]
3.14
function
elementary operation performed by the system which, in conjunction with other elementary
operations (system functions), enables the system to perform a task
3.15
high voltage
the set of voltage levels in excess of low voltage
[SOURCE: IEC 60050-601:1985, 601-01-27 modified]
3.16
hull return system
system in which insulated conductors are provided for connection to one pole or phase of the
supply, the structure of the unit or other permanently earthed structure being used for
effecting connections to the other pole or phase
3.17
integrity
capability of a system to satisfactorily perform the required functions under all the stated
conditions within a stated period of time
[SOURCE: IEC 6005-191:1990, 191-19-07, modified]

3.18
low voltage
a set of voltage levels used for the distribution of electricity and whose upper limit is generally
accepted to be 1 000 V a.c.
[SOURCE: IEC 60050-601:1985, 601-01-26]
3.19
control room
room or spaces where centralized controls and measuring and monitoring equipment for main
equipment and essential auxiliary machinery are located together with the appropriate means
of communication
– 14 – 61892-2 © IEC:2012(E)
3.20
maintainability
ability of an item under given conditions of use, to be retained in, or restored to, a state in

which it can perform a required function, when maintenance is performed under given

conditions and using stated procedures and resources

[SOURCE: IEC 60050-191:1990, 191-02-07]

3.21
over-current
a current exceeding the rated current

[SOURCE: IEC 60050-441:1984, 441-11-06]
3.22
over-current discrimination
co-ordination of the operating characteristics of two or more over-current protective devices
such that, on the incidence of over-currents within stated limits, the device intended to
operate within these limits does so, while the other(s) does (do) not
[SOURCE: IEC 60050-441:1984, 441-17-15]
3.23
overload
operating conditions in an electrically undamaged circuit, which cause an over-current
[SOURCE: IEC 60050-441:1984, 441-11-08]
3.24
partial discrimination
partial selectivity
over-current discrimination where, in the presence of two or more over-current protective
devices in series, the protective device closest to the fault effects the protection up to a given
level of short-circuit current without causing the other protective devices to operate
3.25
primary distribution system
system having electrical connection with the main source of electrical power
3.26
reliability
the probability that an item can perform a required function under given conditions for a given
time interval
[SOURCE: IEC 60050-191:1990 191-12-01, modified]
3.27
safety functions
functions intended to prevent harm or danger to personnel
3.28
secondary distribution system
system having no electrical connection with the main source of electrical power, e.g. isolated
therefrom by a double-wound transformer or motor-generator
3.29
short-circuit
accidental or intentional conductive path between two or more conductive parts forcing the
electric potential differences between these conductive parts to be equal to or close to zero

61892-2 © IEC:2012(E) – 15 –
[SOURCE: IEC 60050-195:1998, 195-04-11]

3.30
software
programme, procedures and associated documentation pertaining to the operation of a

computer system and including application (user) programme, middleware and operating

system (firmware) programme
3.31 Sources of electrical power

3.31.1
emergency source of electrical power
source of electrical power intended to supply the emergency system in the event of failure of
the supply from the main source of electrical power
3.31.2
main source of electrical power
source of electrical power intended to supply all services necessary for maintaining the unit in
normal o
...