IEC 61892-2:2012
(Main)Mobile and fixed offshore units - Electrical installations - Part 2: System design
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.
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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
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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
...
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