Section 1 General Requirements
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Construction & Classification of Submersibles & Diving Systems, July 2022 - Part 6 Electrical Installations and Control Engineering Systems - Chapter 1 Electrical Installations - Section 1 General Requirements

Section 1 General Requirements

Parent topic: Chapter 1 Electrical Installations

1.1 General

1.1.1 The requirements of this Chapter apply to submersibles, diving systems and deck decompression chambers. Attention should also be given to any relevant Statutory Regulations of the country in which the unit is to be operated.

1.1.2 The Committee will be prepared to give consideration to special cases or to arrangements which are equivalent to the Rules.

1.2 Plans

1.2.1 At least three copies of the plans and particulars Pt 6, Ch 1, 1.2 Plans 1.2.2 to Pt 6, Ch 1, 1.2 Plans 1.2.12 are to be submitted for consideration. Single copies only are required of plans in Pt 6, Ch 1, 1.2 Plans 1.2.13 to Pt 6, Ch 1, 1.2 Plans 1.2.16. Additional copies are to be submitted when requested.

1.2.2 Single line diagrams of main and emergency power systems and lighting which is to include:
  1. Ratings of electrical machines, transformers, batteries and semiconductor converters;
  2. All feeders connected to the main and emergency switchboards;
  3. Distribution boards;
  4. Insulation type, size and current loadings of cables;
  5. Make, type and rating of circuit breakers and fuses.
1.2.3 Simplified diagrams of interconnector circuits and feeder circuits showing:
  1. Protective devices, e.g. short-circuit, overload, reverse power protection;
  2. Instrumentation and synchronizing devices;
  3. Preference tripping;
  4. Remote stops;
  5. Earth fault indication/protection.
1.2.4 A general arrangement drawing of the electrical equipment containing at least the following information:
  1. Voltage rating of the system;
  2. Power or current ratings of electrical consumers;
  3. Switchgear, indicating settings for short-circuit and overload protection; fuses with details or current ratings;
  4. Cable types and cross-sections.

1.2.5 Calculations of short circuit current at main and emergency switchboards and, where requested, distribution boards, together with details of circuit-breaker and fuse operating times and discrimination curves showing compliance with the requirements of the Rules and Regulations for the Classification of Ships, July 2022 Pt 6, Ch 2, 6.1 General and Pt 6, Ch 2, 11.6 Conductor size 11.6.2.

1.2.6 For a diving system installed in a location where explosive gas atmospheres can occur, a drawing of the ship showing hazardous zones and spaces in and close to that location.

1.2.7 Details of electrical equipment for use in explosive gas atmospheres, including:
  1. Type of equipment;
  2. Type of protection, e.g. Ex ‘d’;
  3. Apparatus group, e.g. IIB;
  4. Temperature class, e.g. T3;
  5. Enclosure ingress protection, e.g. IP55;
  6. Certifying authority;
  7. Certificate number;
  8. Location of equipment Where uncertified equipment is permitted by the Rules and Regulations for the Classification of Ships, July 2022, Pt 6, Ch 2, 14 Electrical equipment for use in explosive gas atmospheres or in the presence of combustible dusts, details of other documentation confirming (b) to (d) may be submitted in place of those listed under (f) and (g).

1.2.8 For battery installations, arrangement plans and calculations are to show compliance with the performance requirements of Pt 6, Ch 1, 2.2 Sources of power 2.2.2, Pt 6, Ch 1, 2.2 Sources of power 2.2.5, Pt 6, Ch 1, 4 Batteries and Pt 6, Ch 1, 9.5 Batteries and the ventilation requirements of the Rules and Regulations for the Classification of Ships, July 2022, Pt 6, Ch 2, 12.5 Thermal management and ventilation.

1.2.9 A schedule of batteries fitted for use for emergency and essential services, giving details of:
  1. Type and manufacturer's type designation;
  2. Voltage and ampere-hour rating;
  3. Location;
  4. Equipment and/or system(s) served;
  5. Maintenance/replacement cycle dates;
  6. Date(s) of maintenance and/or replacement; and
  7. For replacement batteries in storage, the date of manufacture and shelf life; with accompanying battery replacement procedure documentation to show compliance with the Rules and Regulations for the Classification of Ships, July 2022, Pt 6, Ch 2, 12.7 Recording of batteries for emergency and essential services.

1.2.10 In order to establish compliance with Pt 6, Ch 1, 2.4 Emergency power 2.4.2, a general arrangement plan showing the location of major items of electrical equipment, and cable or wiring routes between these items.

1.2.11 Arrangement plans of main and emergency switchboards.

1.2.12 Schedule of normal and emergency operating loads on the system estimated for the different operating conditions expected.

1.2.13 In order to establish compliance with the relevant requirements of Pt 6, Ch 1, 1.5 Design and construction 1.5.2 evidence is to be submitted to demonstrate the suitability of electrical equipment for its intended purpose in the conditions in which it is expected to operate.

1.2.14 The energy balance of the main emergency power supply systems for diving systems having their own generating plant.

1.2.15 Drawings of switchgear and generating plant.

1.2.16 Complete documentation for electric motor drives with details of control, measuring and monitoring systems.

1.2.17 Battery installation drawings with details of battery types, chargers and, as applicable, battery room ventilation or, for example for a submersible, where batteries are installed inside a pressure vessel or other container mounted on the outside of the pressure hull.

1.2.18 Details of electrical penetrations through compression chamber walls, see Pt 6, Ch 1, 7 Electrical Pressure Hull Penetrators and Cable Connectors.

1.2.19 Drawings and descriptions of all electrical components installed in compression chambers.

1.3 Surveys

1.3.1 Equipment is to be selected and installed in accordance with the relevant requirements of this Chapter and surveyed by the Surveyors.

1.3.2 Electrical equipment, essential for the safety of the unit and personnel, is to be supplied with a manufacturer's works test certificate showing compliance with the constructional standard(s) as referenced by the relevant requirements.

1.4 Additions or alterations

1.4.1 No addition, temporary or permanent, is to be made to the approved load of an existing installation until it has been ascertained that the current carrying capacity and the condition of the existing equipment are adequate for the increased load.

1.4.2 Plans are to be submitted for consideration, and the alterations or additions are to be carried out under the survey, and to the satisfaction, of the Surveyors.

1.4.3 When it is proposed to replace permanently installed batteries with batteries of a different type, details are to be submitted for consideration to ensure continued compliance with the relevant requirements of this Chapter.

1.5 Design and construction

1.5.1 Services essential for safety of the unit and personnel are to be maintained under emergency conditions and the safety of personnel from electrical hazards is to be assured.

1.5.2 The design and installation of all electrical equipment is to be compatible with the special conditions pertaining to marine service. In particular, equipment is to be suitable for operation under conditions of:
  1. High humidity;
  2. Hyperbaric pressure;
  3. Salt laden temperature;
  4. Vibration;
  5. Possible oxygen enrichment.
  6. Inclination of the facility.

For environmental conditions and inclination requirements pertaining to diving systems refer to Pt 5, Ch 1, 2 Principles for design and construction of diving systems.

1.5.3 Additional requirements for the location, installation and construction of electrical equipment are given in the Rules and Regulations for the Classification of Ships, July 2022,Pt 6, Ch 2, 1.1 General to Pt 6, Ch 2, 1.17 Operation under flooding conditions, which are to be complied with where applicable.

1.5.4 Equipment for services essential for the safety of the unit, and, in the case of submersibles, electrical propelling machinery and associated equipment together with services essential for propulsion, are to be constructed in accordance with the relevant requirements of this Chapter.

1.5.5 The design and installation of other equipment is to be such that risk of fire due to its failure is minimized. It is, as a minimum, to comply with a National or International Standard revised where necessary for ambient conditions.

1.5.6 Electrical equipment is to be suitable for its intended purpose and accordingly, whenever practicable, be selected from the List of Type Approved Products published by LR. A copy of the Procedure for LR Type Approval System will be supplied on application.

1.5.7 Electrical equipment for use underwater is to operate safely at the maximum design depth of the unit. Refer to IMCA D 045 “Code of Practice for The Safe Use of Electricity Under Water” for additional guidance.

1.5.8 Electrical equipment providing essential services is to be of a continuous rating.

1.5.9 All electrical equipment supplied from the main and emergency sources of electrical power and electrical equipment for essential and emergency services supplied from D.C. sources of electrical power is to be so designed and manufactured that it is capable of operating satisfactorily under normally occurring variations of voltage and frequency.

1.5.10 Unless specified otherwise, a.c. electrical equipment is to operate satisfactorily with the following simultaneous variations, from their nominal value, when measured at the consumer input terminals:
  1. Voltage:
    • Permanent variations +6%, –10%
    • Transient variations due to step changes in load ±20%
    • Recovery time 1,5 seconds
  2. Frequency:
    • Permanent variations ±5%
    • Transient variations due to step changes in load ±10%
    • Recovery time 5 seconds
    A maximum rate of change of frequency not exceeding ±1,5 Hz per second during cyclic frequency fluctuations.

1.5.11 Unless specified otherwise, the total harmonic distortion (THD) of the voltage waveform at any a.c. switchboard is not to exceed 8 per cent of the fundamental for all frequencies up to 50 times the supply frequency and no voltage at a frequency above 25 times supply frequency is to exceed 1,5 per cent of the fundamental of the supply voltage. THD is the ratio of the r.m.s. value of the harmonic content to the r.m.s. value of the fundamental, expressed in per cent and may be calculated using the expression:

Where:
Vh = r.m.s. amplitude of a harmonic voltage of order h
V1 = r.m.s. amplitude of the fundamental voltage.
1.5.12 Unless specified otherwise, d.c. electrical equipment is to operate satisfactorily with the following simultaneous variations, from their nominal value, when measured at the consumer input terminals:
  1. When supplied by d.c. generator(s) or a rectified a.c. supply:
    • Voltage tolerance (continuous) ±10%
    • Voltage cyclic variation deviation 5%
    • Voltage ripple 10%
    • (a.c. R.M.S. over steady state D.C. voltage);
  2. When supplied by batteries:
    1. Equipment connected to the batteries during charging: Voltage tolerance +30%, –25%;
    2. Equipment not connected to batteries during charging: Voltage tolerance +20%, –25%.
    Different voltage variations as determined by the charging/discharging characteristics, including ripple voltage from the charging device, may be considered. When battery charger/battery combinations are used as d.c. power supply systems adequate measures are to be taken to keep the voltage within the specified limits during charging, boost charging and discharging of the battery.

1.5.13 Electrical conductors are to be of sufficient size for the purposes for which they are to be used. The requirements for construction, selection and testing of electrical cables are given in the Rules and Regulations for the Classification of Ships, July 2022, Pt 6, Ch 2, 11.1 General to Pt 6, Ch 2, 11.16 Joints and branch circuits in cable systems, which are to be complied with where applicable.

1.5.14 Effective means are to be provided so that all voltages may be cut-off from every circuit and sub-circuit, and from all equipment, as may be necessary to minimize danger.

1.5.15 Conductors and equipment exposed to a flammable or explosive atmosphere are to be constructed or protected and such special protection taken, as may be necessary to minimize danger. Compliance with IEC 60092-502: Electrical Installations in Ships – Tankers – Special Features, Clauses 5, 6 and 7, Electrical systems, Electrical equipment, and Installation, respectively, will, in general, be accepted. Where equipment can be subjected to air pressure or oxygen concentration significantly differing from normal atmospheric conditions, the suitability of that equipment for those pressures and oxygen concentrations is to be confirmed by a competent authority. Where requirements are imposed by the rules or regulations applicable to the vessel on which a diving system or deck decompression chamber can be located, the equipment is, in addition, to comply with those requirements.

1.5.16 Electrical devices in a hyperbaric chamber should not cause a risk of ignition. Information regarding this area is available in NFPA 99, section 20 and NFPA 53. In addition consideration is to be given to:
  1. Using low energy (low voltage and low current) devices;
  2. Placing the power source of the device outside the chamber or within a sealed unit;
  3. Placing the power switches of the device outside the chamber or the use of reed switches.

If in any doubt, the electrical device should not be installed in the hyperbaric chamber.

1.5.17 All electrical equipment including motor rotors and stators should meet a T5 rating (surface temperature not to exceed 100°C).

1.5.18 The quantity of material which can emit toxic fumes on overheating is to be minimized. As far as is practicable, materials used for electrical equipment, cables and accessories are not to be capable of producing excessive quantities of smoke and toxic products.
Note Compliance with IEC 60695: Fire hazard testing, or an alternative and acceptable Standard, will satisfy this requirement.

1.5.19 Each compression chamber compartment and each diving bell is to be equipped with a suitable normal and emergency lighting system.

1.5.20 The normal lighting system is to be so designed and installed that the intensity of the lighting inside the chamber is at least 300 lux. As far as possible, interior lighting should be free from glare. In all chambers and diving bells the normal lighting shall have a colour rendering index (CRI) of not less than 50 (to facilitate a change in skin tone).

1.5.21 The emergency lighting system is to be designed and installed in such a way that a diver inside the chamber is fully able to take readings and operate controls in every compartment.

1.5.22 Safeguards against the bursting of light fittings are to be agreed with LR in each case. Light fittings and lamps should be rated to withstand 1.3 times maximum working pressure, the use of LED lamps should be considered.

1.5.23 All electrical equipment necessary to the safe completion of the mission, including equipment that may be need during an emergency, is to be suitable for 100 per cent relative humidity, or the conditions anticipated on board the unit.

1.5.24 Electronic automation systems should comprise easily replaceable assemblies, of the plug-in type wherever possible. Standardization of units is to be encouraged and the number of assembly types is to be kept small in order to minimize the spare parts inventory.

1.5.25 Plug-in cards must be clearly marked or coded to prevent inadvertent confusion.

1.5.26 Measures must be taken to prevent condensation inside electronic units, even when switched off. Shutdown heating is recommended.

1.5.27 Wherever possible, automation equipment should be capable of operation without forced ventilation. Any cooling system used is to be monitored.

1.5.28 Components must be effectively secured. Any mechanical loading of wires and soldered connections due to vibration or jolting is to be mitigated.

1.5.29 The construction of systems and units is to be simple and straightforward. Good accessibility is to be ensured to facilitate measurements and repairs.

1.6 Bonding

1.6.1 Exposed non-current-carrying metallic parts of equipment are to be connected together and earthed to the metallic structure of the unit in such a way as to give a substantially equal potential and earth loop impedance sufficiently low to ensure correct operation of protective devices.

1.6.2 Further requirements for earthling of non-current carrying parts are given in the Rules and Regulations for the Classification of Ships, July 2022, Pt 6, Ch 2, 1.12 Earthing of non-current carrying parts, which are to be complied with where applicable.

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