Section
1 General requirements
1.1 General
1.1.1 The requirements of this Chapter apply to all offshore units defined in
Pt 1, Ch 2 Classification Regulations except where otherwise
stated. Where applicable, the relevant requirements for electrical services
necessary to maintain the unit in a normal sea-going, operational and habitable
condition, for electrical services essential for safety and for the safety of crew
and unit from electrical hazards as stated in Pt 6, Ch 2 Electrical Engineering of the Rules and Regulations for the
Classification of Ships (hereinafter referred to as the Rules for Ships) are
to be complied with.
1.1.2 Attention is also to be given to any relevant statutory regulation of
the National Administration in the country in which the unit is to operate and/or be
registered.
1.1.3 Where reference is made to the requirements of the Rules for Ships,
references therein to ship(s) are to be understood to refer to unit(s).
1.2 Documentation required for design
review
1.2.2 Electrical system study and calculations are to be in accordance with the
IEC 61892-2:2012, Mobile and fixed offshore units Electrical installations
Part 2: System design, Section 9, or an alternative relevant International
or National Standard.
1.2.3 The general arrangement of the unit, showing the hazardous zones and
spaces, is to include details on the permitted temperature class and gas group of
the electrical equipment. The temperature class and apparatus group of the
electrical equipment are associated with the ignition temperature and energy
required for ignition of the hazardous substances.
1.3 Documentation required for supporting
evidence
1.3.2 A description of the philosophy of the systems of power generation and
distribution, describing their modes of operation under normal and emergency
conditions, is to be submitted.
1.3.3 Arrangement plans of main and emergency switchboards, section boards,
and documentation that demonstrates that creepage and clearance distances are in
accordance withPt 6, Ch 2, 7.5 Creepage and clearance distances . The form factor of internal separation of low
voltage switchgear and control gear assemblies is to be in accordance with IEC
61439-2, Low-voltage switchgear and control gear assemblies Part 2: Power
switchgear and control gear assemblies, or alternative relevant
International or National Standards. The form factor is to be stated, and the
arrangement plans are to show how the form factor has been achieved.
1.4 Surveys
1.4.1 The equipment required to be surveyed is given in Pt 6, Ch 2, 1.4 Surveys of the Rules for Ships, which are to be complied
with.
1.5 Additions or alterations
1.6 Definitions
1.6.2 Essential services are those necessary for the propulsion and safety of
the unit, such as the following:
1.6.4 Services such as the following, which are additional to those in Pt 6, Ch 2, 1.6 Definitions 1.6.2 and Pt 6, Ch 2, 1.6 Definitions 1.6.3, are considered necessary to maintain the unit
in a normal and sea-going operation and habitable condition:
- Drilling plant equipment;
- Processing and production equipment;
- Hotel services, other than those required for habitable
conditions;
- Thrusters, other than those for essential services; and
- Lifting appliances for the transfer of material, equipment or
personnel; and
- Pipe-laying systems.
1.7 Design and construction of
equipment
1.7.1 The requirements for design and construction are given in Pt 6, Ch 2, 1.7 Design and construction of the Rules for Ships, which are to be complied
with. Additions or amendments to these requirements are given in the following
paragraph(s) of this sub-Section.
1.7.2 Equipment or apparatus required to be suitable for use in an explosive
gas atmosphere shall comply with the requirements of Pt 7, Ch 2 Hazardous Areas and Ventilation, Pt 6, Ch 2, 8 Protection from electric arc hazards within electrical equipment, Pt 6, Ch 2, 9 Rotating machines, Pt 6, Ch 2, 10 Converter equipment and Pt 6, Ch 2, 11 Electrical cables and busbar trunking systems (busways), IEC 60092-502, Electrical installations in
ships Part 502: Tankers Special features, IEC 61892-7, Mobile and fixed
offshore units Electrical installations Part 7: Hazardous areas or
alternative relevant International or National Standard. Such equipment shall be
constructed and tested in accordance with the requirements of the IEC 60079 series,
Explosive atmospheres (or alternative relevant International or National
Standard) and be fit for purpose for the actual ambient temperature and other
environmental conditions.
1.8 Quality of power supplies
1.8.1 The requirements for quality of power supplies are given in Pt 6, Ch 2, 1.8 Quality of power supplies of the Rules for Ships and IEC 61892- 1:2010,
Mobile and fixed offshore units Electrical installations Part 1: General
requirements and conditions, Section 4.7, which are to be complied with.
1.9 Ambient reference and operating
conditions
1.9.1 The requirements for ambient reference and operating conditions are given
in Pt 6, Ch 2, 1.9 Ambient reference and operating conditions of the Rules for Ships, which are to be complied
with where applicable. Additions or amendments to these requirements are given in
the following paragraph(s) of this sub-Section.
1.9.2 The rating for classification purposes of essential electrical equipment
is to be based on the maximum ambient air and water temperatures expected at the
location of the unit. In the absence of precise temperatures, the following
temperatures are to be assumed:
- For units intended to operate within the
tropical belt (i.e. between latitudes 35°N and 20°S):
- Primary cooling water supply 32°C
- Cooling air temperature 45°C.
- For units intended to operate in northern or
southern waters outside the tropical belt:
- Primary cooling water supply 25°C
- Cooling air temperature 40°C.
1.9.3 The air temperature range considered with respect to the selection of
equipment, the safe operation of which may be subject to limitations on ambient
temperature (e.g. safe type electrical equipment), is to be that expected at the
location of the equipment, taking into account local sources of heat and the range
of ambient air temperature expected at the location of the unit. In the absence of
precise information, the maximum air temperature is to be assumed to be that of the
cooling air temperature given in Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2.(a) or Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2.(b), as appropriate, and the minimum is to
be assumed to be minus 20°C, or as determined by reference to Annex B of IEC
61892-1, Mobile and fixed offshore units Electrical installations Part 1:
General requirements and conditions.
1.9.4 Where electrical equipment is installed within environmentally controlled
spaces, the ambient temperature for which the equipment is suitable for operation at
its rated capacity may be reduced to a value not more than 10°C below that
determined by reference to Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2 or Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.3, provided:
- the equipment is not for use for emergency services and is
located outside of machinery space(s);
- temperature control is achieved by an independent and redundant
cooling unit(s) so arranged that, in the event of loss of one cooling unit,
for any reason, the remaining unit(s) will be capable of satisfactorily
maintaining the design temperature;
- the equipment is able to be initially set to work safely within
the cooling temperature (see
Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2.(a) and Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2.(b)) until such a time that the
lesser ambient temperature may be achieved; the cooling equipment is to be
rated for an ambient temperature of not less than the cooling temperature
(see
Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2.(a) and Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2.(b)); and
- alarms are provided, at a continuously attended control
station, to indicate any malfunction of the cooling units. See also
Pt 6, Ch 1, 1.3 Control, alarm and safety equipment 1.3.3.
1.10 Inclination of the unit
1.10.1 The requirements for inclination of the unit are given in Pt 6, Ch 2, 1.10 Inclination of ship of the Rules for Ships, which are to be complied
with where applicable. Additions or amendments to these requirements are given in
the following paragraph(s) of this sub-Section.
1.10.2 Essential and emergency electrical equipment is to operate satisfactorily
under the conditions as shown in Table 2.1.1 Inclination of other
units for column-stabilised,
tension-leg and self-elevating units. For buoy and deep draught caisson units, the
angles of inclination will be specially considered in each case.
Table 2.1.1 Inclination of other
units
Installations,components
|
Angle of inclination, degrees in any
direction
|
Column-stabilised units
|
Self-elevating units
|
Static
|
Dynamic
|
Static
|
Dynamic
|
Essential electrical
equipment
|
15
|
22,5
|
10
|
15
|
Electrical equipment for
emergency services
|
25
|
25
|
15
|
15
|
1.11 Location and construction of
equipment
1.11.1 The requirements for location and construction are given in IEC
61892-1:2010, Mobile and fixed offshore units Electrical installations Part
1: General requirements and conditions, Sections 4.15 to 4.20 and Pt 6, Ch 2, 1.11 Location and construction of the Rules for Ships, which are to be complied
with. Additions or amendments to these requirements are given in the following
paragraph(s) of this sub-Section.
1.11.2 Electrical equipment, as far as is practicable, is to be located:
- Such that it is accessible for the purpose of maintenance and
survey;
- Clear of flammable material;
- In spaces adequately ventilated to remove the waste heat
liberated by the equipment under full load conditions, at the ambient
conditions specified in Pt 6, Ch 2, 1.9 Ambient reference and operating conditions;
- Where flammable gases cannot accumulate. If this is not
practicable, electrical equipment is to comply with the relevant
requirements of Pt 7, Ch 2, 8 Electrical equipment for use in explosive gas atmospheres;
- Where it is not exposed to the risk of mechanical injury or
damage from water, steam or oil; and
- Clear of areas at risk of cryogenic spills.
1.12 Earthing of non-current-carrying
parts
1.12.1 The requirements for earthing of non-current-carrying parts are given in
Pt 6, Ch 2, 1.12 Earthing of non-current carrying parts of the Rules for Ships and IEC 61892-6:2007
Section 4 Mobile and fixed offshore units Electrical installations Part 6:
Installation which are to be complied with. Additions or amendments to these
requirements are given in the following paragraph(s) of this sub-Section.
1.12.2 Where the current-carrying conductor exceeds 120 mm2, a 70
mm2 earthing conductor is permitted, provided that the circuit
protection arrangements are such as will prevent an excessive temperature rise under
fault conditions.
1.13 Bonding for the control of static
electricity
1.13.1 The requirements for bonding for the control of static electricity are
given in Pt 6, Ch 2, 1.13 Bonding for the control of static electricity of the Rules for Ships, IEC 60092-502:1999,
Electrical installations in ships Part 502: Tankers Special features,
Section 5.5 and IEC 61892-6:2007, Mobile and fixed offshore units Electrical
installations Part 6: Installation, Section 4, which are to be complied
with where applicable. Additions or amendments to these requirements are given in
the following paragraph(s) of this sub-Section.
1.13.2 Bonding straps for the control of static electricity are required for
storage tanks, process plant and piping systems located in hazardous areas, or for
flammable products and solids liable to release flammable gas and/or combustible
dust, which are not permanently connected to the structure of the unit either
directly or via their bolted or welded supports and where the resistance between
them and the structure exceeds 1MΩ.
1.14 Alarms
1.14.1 The requirements for alarms are given in IEC 61892-2:2012, Mobile and
fixed offshore units Electrical installations Part 2: System design,
Section 12.12.2.4 and Pt 6, Ch 2, 1.14 Alarms of the Rules for Ships which are to
be complied with. Additions or amendments to these requirements are given in the
following paragraph(s) of this sub-Section.
1.14.3 Electrical equipment and cables for emergency alarms are to be so
arranged that the loss of alarms in any one area due to localised fire, cryogenic
spill, collision, flooding or similar damage is minimised, see
Pt 6, Ch 2, 1.16 Operation under fire conditions, Pt 6, Ch 2, 1.17 Operation under flooding conditions and Pt 11, Ch 5, 7 Cryogenic releases.
1.15 Labels, signs and notices
1.16 Operation under fire conditions
1.16.1 The requirements for operation under fire conditions are given in Pt 6, Ch 2, 1.16 Operation under fire conditions of the Rules for Ships, which are to be
complied with. Additions or amendments to these requirements are given in the
following paragraph(s) of this sub-Section.
1.16.2 The following emergency services and their emergency power supplies are
also required to be capable of being operated under fire conditions:
1.17 Operation under flooding
conditions
1.18 Protection of electrical equipment against
the effects of lightning strikes
1.19 Programmable electronic systems
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