IEC 61892-2:2019

IEC 61892-2 ®
Edition 3.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Mobile and fixed offshore units – Electrical installations –
Part 2: System design
Unités mobiles et fixes en mer – Installations électriques –
Partie 2: Conception du système
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IEC 61892-2 ®
Edition 3.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Mobile and fixed offshore units – Electrical installations –

Part 2: System design
Unités mobiles et fixes en mer – Installations électriques –

Partie 2: Conception du système

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 47.020.60 ISBN 978-2-8322-6667-0

– 2 – IEC 61892-2:2019 © IEC 2019
CONTENTS
FOREWORD . 8
INTRODUCTION . 10
1 Scope . 11
2 Normative references . 12
3 Terms, definitions and abbreviated terms . 13
3.1 Terms and definitions . 13
3.2 Abbreviated terms . 20
4 Sources of electrical power for manned units . 20
4.1 General . 20
4.2 Main sources of electrical power . 21
4.2.1 Common requirements . 21
4.2.2 Capacity of main and essential power source . 22
4.2.3 Load shedding arrangement . 22
4.3 Essential source of electrical power . 23
4.4 Emergency source of electrical power . 23
4.5 Starting arrangements for emergency generators . 26
4.6 Additional requirements for periodically unattended machinery spaces . 27
4.7 Uninterruptible power system (UPS) source of power . 27
4.7.1 General . 27
4.7.2 UPS functionality – Uninterruptible source of power for critical/sensitive
loads . 28
4.7.3 UPS – Design planning issues . 28
4.8 Transmission systems including main power from shore . 30
4.9 Alternative sources of power . 31
5 Sources of electrical power for unmanned units . 32
5.1 General . 32
5.2 Power sources . 32
5.2.1 Sources to be evaluated . 32
5.2.2 Cable from other unit or from shore . 32
5.2.3 Local generator (gas or diesel) . 32
5.2.4 Alternative sources of power . 32
5.2.5 UPS . 33
5.3 Factors affecting power supply requirements . 33
6 System earthing . 33
6.1 General requirements . 33
6.2 Neutral earthing for systems up to and including 1 000 V AC . 34
6.3 Neutral earthing for systems above 1 000 V AC . 34
6.4 Parallel operated power sources . 35
6.5 Earthing resistors, connection to hull/structure . 35
7 Distribution systems . 36
7.1 DC distribution systems . 36
7.1.1 Types of distribution systems . 36
7.1.2 TN DC systems. 37
7.1.3 IT DC systems . 40
7.1.4 DC voltages . 41
7.2 AC distribution systems . 42

7.2.1 Primary AC distribution systems . 42
7.2.2 Secondary AC distribution systems . 42
7.2.3 TN AC systems . 42
7.2.4 IT AC systems . 44
7.2.5 AC voltages and frequencies . 44
7.2.6 Earthing systems . 46
8 Distribution system requirements . 46
8.1 Methods of distribution . 46
8.2 Balance of loads . 47
8.2.1 Balance of load on three-wire DC systems . 47
8.2.2 Balance of loads in three- or four-wire AC systems . 47
8.3 Final circuits . 47
8.3.1 General . 47
8.3.2 Final circuits for lighting . 47
8.3.3 Final circuits for heating . 47
8.3.4 Final circuits for sockets . 47
8.4 Control circuits . 48
8.4.1 Supply systems and nominal voltages. 48
8.4.2 Circuit design . 48
8.4.3 Protection . 48
8.4.4 Arrangement of circuits . 49
8.5 Motor circuits . 49
8.5.1 Starting of motors . 49
8.5.2 Means of disconnection . 50
8.5.3 Starters remote from motors . 50
8.6 Isolation of supply to galley . 50
9 Cables and wiring systems . 50
9.1 Cables . 50
9.2 Voltage drop . 51
9.3 Demand factors . 51
9.3.1 Final circuits . 51
9.3.2 Circuits other than final circuits . 51
9.3.3 Application of diversity and demand factors . 51
9.4 Motor circuits . 51
9.5 Cross-sectional areas of conductors . 52
9.6 Correction factors for cable grouping . 52
9.7 Separation of circuits . 52
10 System study and calculations . 53
10.1 Electrical studies – General . 53
10.2 Electrical load study . 54
10.3 Load flow calculations . 55
10.4 Short-circuit calculations . 56
10.5 Protection and discrimination study . 58
10.6 Power system dynamic calculations . 59
10.7 Calculation of harmonic currents and voltages . 61
11 Protection . 61
11.1 General . 61
11.2 Characteristics and choice of protective devices with reference to short-
circuit rating . 62

– 4 – IEC 61892-2:2019 © IEC 2019
11.2.1 General . 62
11.2.2 Protective devices . 62
11.2.3 Backup protection . 63
11.2.4 Rated short-circuit breaking capacity . 63
11.2.5 Rated short-circuit making capacity . 64
11.2.6 Co-ordinated choice of protective devices with regard to discrimination
requirements . 65
11.3 Choice of protective devices with reference to overload . 65
11.3.1 Protective devices . 65
11.3.2 Fuses for overload protection . 65
11.4 Choice of protective devices with regard to their application . 65
11.4.1 General . 65
11.4.2 Generator protection . 65
11.4.3 Protection of UPS . 66
11.4.4 Protection of transformers . 67
11.4.5 Transformers – Isolation of windings. 67
11.4.6 Circuit protection . 67
11.4.7 Motor protection . 67
11.4.8 Protection of lighting circuits . 68
11.4.9 Protection of power from external sources . 68
11.4.10 Secondary cells and battery protection . 68
11.4.11 Protection of static or solid-state devices . 68
11.4.12 Protection for heat tracing systems . 69
11.5 Undervoltage protection . 69
11.5.1 Generators . 69
11.5.2 AC and DC motors . 69
11.6 Overvoltage protection . 69
11.6.1 General . 69
11.6.2 AC machines . 69
11.6.3 DC networks . 69
12 Lighting . 70
12.1 General . 70
12.2 General lighting system . 70
12.3 Emergency lighting system . 70
12.4 Escape lighting system . 71
12.5 Lighting circuits in machinery spaces, accommodation spaces, open deck
spaces, etc. . 71
12.6 Navigation and obstruction signals and lights . 71
13 Energy control, monitoring and alarm system . 72
13.1 General . 72
13.2 Alarm system . 72
13.3 Network topology . 72
13.4 Router communication . 72
13.5 Communication protocols . 72
13.6 Monitoring and fault diagnosis . 73
13.7 Cybersecurity . 73
13.8 Energy management and control systems (EMCS) . 73
13.8.1 General . 73
13.8.2 EMCS architecture . 73

13.8.3 Interaction with protection system . 74
13.8.4 Performance . 74
13.9 Electromagnetic compatibility . 74
13.10 Time identification and event logs . 75
13.11 Remote controls . 75
13.11.1 Continuous status information. 75
13.11.2 Independent control . 75
13.11.3 Exclusive control . 75
13.11.4 Interlocks in operative command. 75
13.12 Human-machine interface . 75
13.13 Emergency stop . 75
13.14 Automatic control of electrical power sources . 75
13.14.1 Initiation of starting commands . 75
13.14.2 Pre-starting conditions . 76
13.14.3 Standby indication . 76
13.15 Automatic connecting onto a dead busbar . 76
13.15.1 Connection at blackout . 76
13.15.2 Short-circuit . 76
13.16 Delayed disconnection . 76
13.17 Automatic starting arrangements for electrical motor-driven auxiliaries . 76
13.17.1 Prevention of overload via sequential restart . 76
13.17.2 Start inhibit . 76
13.18 General alarm systems . 76
13.18.1 Audibility. 76
13.18.2 Minimum sound level . 77
13.18.3 Fault tolerance. 77
13.18.4 Power supplies . 77
13.19 System integration . 77
13.19.1 Alarm functions . 77
13.19.2 Essential and emergency control functions . 77
13.20 Software . 78
13.20.1 Version control of software . 78
13.20.2 Configuration – Support functions . 78
13.20.3 Documentation . 78
13.21 Tests . 79
13.21.1 General . 79
13.21.2 Hardware . 79
13.21.3 Software . 79
13.21.4 System testing . 79
14 Special facilities – Swivel/turret . 80
14.1 Standards, codes and regulations . 80
14.2 Bonding and protective earthing of power swivel . 80
Annex A (informative) Essential source of electrical power . 81
Annex B (informative) Emergency source of electrical power . 82
Annex C (informative) Applicable examples of HVDC VSC technologies . 83
Annex D (informative) Swivel/turret . 87
D.1 General . 87
D.2 Swivel design and service location . 87

– 6 – IEC 61892-2:2019 © IEC 2019
D.3 Fault exposure of high-voltage electrical swivels . 88
D.4 Enclosure and purging system . 88
D.5 Ingress protection . 88
D.6 Anti-condensation . 89
D.7 Inspection and functional testing of swivel unit . 89
Annex E (informative) Guidelines for design of unmanned units . 90
E.1 Factors affecting power supply requirements . 90
E.2 Guideline for defining power sources requirement . 90
E.2.1 One main power supply and UPS. 90
E.2.2 One emergency power supply and UPS . 91
E.2.3 One main power supply, one emergency power supply and UPS . 91
E.2.4 Renewable sources of energy . 91
E.3 Layout. 92
E.4 Switchboard arrangements . 92
E.5 High-voltage equipment . 94
E.6 Lighting system . 95
Annex F (informative) Alternative sources of electrical power . 96
F.1 General . 96
F.2 Photovoltaic system . 96
F.3 Wind turbine system . 97
F.4 Microturbines . 100
F.5 Closed cycle vapour turbines (CCVT). 101
F.6 Thermoelectric generators (TEG) . 102
Annex G (informative) Illumination level . 104
G.1 General illumination level . 104
G.2 Emergency lighting . 104
G.3 Escape lighting . 104
G.4 Verification of lighting level . 105
Annex H (informative) Enhanced software simulation . 106
H.1 General . 106
H.2 Scope of HiL testing . 106
H.3 Schedule and work process . 106
H.4 Requirements relating to the control system vendor or system integrator . 106
H.5 Documentation and approval . 107
Annex I (informative) Architecture for energy control, monitoring and alarm system –
Level reference and segmentation architecture . 108
Bibliography . 109

Figure 1 – Continuity of supply/continuity of service . 15
Figure 2 – Power system hierarchy in an offshore unit . 21
Figure 3 – TN-S DC system . 38
Figure 4 – TN-C DC system . 39
Figure 5 – TN-C-S DC system . 40
Figure 6 – IT DC system . 41
Figure 7 – TN-S AC system . 43
Figure 8 – TN-C-S AC system . 43
Figure 9 – TN-C AC system . 44

Figure 10 – IT AC system . 44
Figure 11 – Use of FCL in emergency switchboard . 64
Figure C.1 – Typical HVDC VSC transmission between onshore grid and offshore
petroleum unit; symmetric monopole . 84
Figure C.2 – Typical symmetric and asymmetric monopole and bipole HVDC VSC

arrangement . 84
Figure C.3 – Principle drawings of possible topology arrangements for two-level (left)
and multi-level (right) types with indication of corresponding filtered (blue) and
non-filtered (green) output voltage wave forms . 86
Figure E.1 – Example of electrical arrangement for an unmanned unit . 93
Figure E.2 – Example of electrical arrangement for an unmanned unit . 94
Figure E.3 – Example of electrical arrangement for an unmanned unit . 94
Figure F.1 – PV Power generating system – Major functional elements, subsystems

and power flow diagram . 97
Figure F.2 – Typical diagram for the island function of a wind generation system –
Unmanned unit . 98
Figure F.3 – Typical diagram for the island function of a wind generation system –
Manned unit . 99
Figure F.4 – Microturbine typical block diagram . 100
Figure F.5 – CCVT operating principle block diagram . 101
Figure F.6 – Typical diagram for the thermoelectric generation system (TEG) . 102
Figure I.1 – IEC 62443 reference architecture . 108

Table 1 – Summary of principal features of the neutral earthing methods . 36
Table 2 – Voltages for DC systems . 41
Table 3 – AC systems having a nominal voltage between 100 V and 1 000 V inclusive
and related equipment . 45
Table 4 – AC three-phase systems having a nominal voltage above 1 kV and not
exceeding 35 kV and related equipment . 46
Table G.1 – General lighting illumination levels . 104
Table G.2 – Recommended measuring points for measuring illumination in an area . 105

– 8 – IEC 61892-2:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MOBILE AND FIXED OFFSHORE UNITS –
ELECTRICAL INSTALLATIONS –
Part 2: System design
FOREWORD
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
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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 third edition cancels and replaces the second edition published in 2012. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the requirement for sources of electrical power has been rewritten. Requirements both for
manned and unmanned units are given. Requirements for essential services of electrical
power have been added;
b) the requirement in relation to dead start has been added;
c) the requirement for emergency stop for motor-driven fuel-oil transfer and fuel-oil pressure
pumps has been added;
d) general requirements regarding cables and wiring systems have been added;
e) the description of unit interfaces to electrical transmission systems has been included;
f) requirements in relation to energy control, monitoring and alarm system have been
rewritten;
g) new clauses regarding swivel/turret and unmanned facilities have been added;
h) informative annexes regarding the following have been added:
– essential source of electrical power;
– emergency source of electrical power;
– applicable examples of HVDC VSC technologies;
– swivel/turret;
– power sources for unmanned units, with separate or combined main and emergency
switchboard;
– alternative power sources of electrical power – general requirements;
– illumination level;
– enhanced software simulation;
– architecture for energy control, monitoring and alarm system.
The text of this International Standard is based on the following documents:
FDIS Report on voting
18/1650/FDIS 18/1661/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61892 series can be found, under the general title Mobile and
fixed offshore units – Electrical installations, on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 10 – IEC 61892-2:2019 © IEC 2019
INTRODUCTION
IEC 61892 forms a series of International Standards for safety in the design, selection,
installation, maintenance and use of electrical equipment for the generation, transmission,
storage, distribution and utilization of electrical energy for all purposes in offshore units which
are used for the purpose of exploration or exploitation of petroleum resources.
This part of IEC 61892 incorporates and coordinates, as far as possible, existing rules and
forms a code of interpretation, where applicable,
...