Section 3 Emergency source of electrical power
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Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Offshore Units, July 2022 - Part 6 Control and Electrical Engineering - Chapter 2 Electrical Engineering - Section 3 Emergency source of electrical power

Section 3 Emergency source of electrical power

Parent topic: Chapter 2 Electrical Engineering

3.1 General

3.1.1 The requirements of this Section apply to units to be classed for unrestricted service. They do not apply to units of less than 500 tons gross tonnage. Alternative arrangements in accordance with the requirements of the National Administration may also be acceptable.

3.1.2 Where it is proposed that a dedicated emergency source of electrical power and its associated transitional source of power will not be provided, the installation is to comply with the requirements of Pt 6, Ch 2, 3.7 Alternative sources of emergency electrical power.

3.1.3 The emergency source of power for units of less than 500 tons gross tonnage will be the subject of special consideration.

3.1.4 For emergency source of electrical power in accommodation units, see Pt 3, Ch 4, 4.2 Emergency source of electrical power.

3.2 Emergency source of electrical power

3.2.1 The general requirements for emergency source of electrical power are given in IEC 61892-2:2012, Mobile and fixed offshore units – Electrical installations – Part 2: System design, Pt 6, Ch 2, 4 External source of electrical power and Pt 6, Ch 2, 3.4 Emergency source of electrical power in cargo ships of the Rules and Regulations for the Classification of Ships, July 2022, 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.

3.2.2 The emergency source of electrical power, associated transforming equipment, if any, transitional source of emergency power, emergency switchboard and emergency lighting switchboard are to be located in a non-hazardous space above the uppermost continuous deck and above the worst damage waterline, inboard of the damage zones, see Pt 4, Ch 7, 2 Definitions and Pt 4, Ch 7, 3 Installation layout and stability. They are not to be located forward of the collision bulkhead, if any.

3.2.3 The space containing:
  • the emergency source of electrical power, associated transforming equipment, if any;
  • the transitional source of emergency electrical power; and
  • the emergency switchboard;
is not to be contiguous to the boundaries of hazardous areas or machinery spaces of Category A or those spaces containing:
  • the main source of electrical power, associated transforming equipment, if any; or
  • the main switchboard.

3.2.4 The electrical power available is to be sufficient to supply all those services that are essential for safety in an emergency, due regard being paid to such services as may have to be operated simultaneously.

Where emergency sources of electrical power such as Uninterruptible Power Systems (UPS) systems are required to support sequential depressurisation systems, the location and integrity of the systems are to meet the requirements of Pt 3, Ch 8, 3.7 Depressurising system 3.7.8. The performance of the sequential depressurisation system shall not be impacted due to the location of UPS or routing of cables in the event of a fire or explosion in the room.

The emergency source of electrical power is to be capable, having regard to starting currents and the transitory nature of certain loads, of supplying simultaneously at least the following services for the periods specified hereinafter, if they depend upon an electrical source of power for their operation:

  1. For a period of 18 hours, emergency lighting:
    1. in alleyways, stairways and exits, giving access to the muster and embarkation stations:
    2. in all service and accommodation alleyways, stairways and exits, personnel lift cars and personnel lift;
    3. in the machinery spaces and main generating stations including their control positions;
    4. in all control stations, machinery control rooms, and at each main and emergency switchboard;
    5. at all stowage positions for fireman’s outfits;
    6. at the steering gear;
    7. at the emergency fire pump, at the sprinkler pump, if any, and at the emergency bilge pump, if any, and at the starting positions of their motors;
    8. in any stored oil pump-room;
    9. at every survival craft preparation station, muster and embarkation station and over the sides;
    10. on helicopter decks, to include deck perimeter lights and helideck status lights, wind direction indicator illumination, and related obstruction lights, if any;
    11. in all spaces from which control of the drilling process or pipe-laying operations (as defined in Pt 3, Ch 17, 1.1 Application 1.1.1) is performed and where controls of machinery essential for the performance of this process, or devices for emergency switching off of the power plant are located; and
    12. at ESD manual activation points.
  2. For a period of 18 hours:
    1. the navigation lights and other lights and sound signals required by the International Regulations for the Prevention of Collisions at Sea in force;
    2. the radio communications as required by Amendments to Chapter IV - Radiocommunications;
    3. permanently installed diving equipment necessary for the safe conduct of diving operations, if dependent upon the unit’s electrical power;
    4. the emergency fire pump if dependent upon the emergency generator for its source of power;
    5. one of the refrigerated liquid carbon dioxide units intended for fire protection, where both are electrically driven;
    6. on column-stabilised units: ballast pump control system, ballast pump status-indicating system, ballast valve control system, ballast valve position indicating system, draft level indicating system, tank level indicating system, heel and trim indicators, power availability indicating system (main and emergency), ballast system hydraulic/pneumatic pressure-indicating system and the largest capacity ballast pump required by Pt 5, Ch 13, 11 Ballast system of the Rules and Regulations for the Classification of Ships, July 2022; and
    7. abandonment systems dependent on electric power.
  3. For a period of 18 hours:
    1. the navigational aids as required by Amendments to Regulation 19–1 - Long-range identification and tracking of ships1 as applicable;
    2. general alarm and communication systems required in an emergency;
    3. intermittent operation of the daylight signalling lamp and the unit’s whistle, the manually operated call points and all internal signals that are required in an emergency;
    4. the fire and gas detection systems and their alarms; and
    5. the capability of closing the blow out preventer and of disconnecting the unit from the wellhead arrangement, if electrically controlled, unless such services have an independent supply from an accumulator battery suitably located for use in an emergency and sufficient for the period of 18 hours.
  4. The steering gear for the period of time required by Pt 5, Ch 19, 6 Emergency power of theRules and Regulations for the Classification of Ships, July 2022.
  5. For a period of four days, any signalling lights or sound signals which may be required for marking offshore structures, unless such services have an independent supply from an accumulator battery suitably located for use in an emergency and sufficient for the period of four days.
  6. For a period of half an hour:
    1. power to operate any watertight doors but not necessarily all of them simultaneously, unless an independent temporary source of stored energy is provided; and
    2. power to operate the controls and indicators provided.
  7. Where applicable, the services required by Pt 6, Ch 2, 2.3 Starting arrangements 2.3.2.
  8. For a minimum of 30 minutes, the ESD system with its indication circuits as required by Pt 7, Ch 1, 7.1 General 7.1.10
3.2.5 The emergency source of electrical power may be either a generator or an accumulator battery, which is to comply with the following:
  1. Where the emergency source of electrical power is a generator it is to be:
    1. driven by a suitable prime mover with an independent supply of fuel, having a flashpoint (closed-cup test) of not less than 43°C;
    2. started automatically upon failure of the main source of electrical power supply unless a transitional source of emergency electrical power in accordance with Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.6 is provided; where the emergency generator is automatically started, it is to be automatically connected to the emergency switchboard; those services referred to in Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.6 are to be connected automatically to the emergency generator; and
    3. provided with a transitional source of emergency electrical power as specified in Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.6 unless an emergency generator is provided capable both of supplying the services mentioned in that paragraph and of being automatically started and supplying the required load as quickly as is safe and practicable subject to a maximum of 45 seconds.
  2. Where the emergency source of electrical power is an accumulator battery it is to be capable of:
    1. carrying the emergency electrical load without recharging while maintaining the voltage of the battery throughout the discharge period within 12 per cent above or below its nominal voltage;
    2. automatically connecting to the emergency switchboard in the event of failure of the main source of electrical power; and
    3. immediately supplying at least those services specified in Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.6.
3.2.6 The transitional source of emergency electrical power where required by Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.5 is to consist of an accumulator battery suitably located for use in an emergency which is to operate without recharging while maintaining the voltage of the battery throughout the discharge period within 12 per cent above or below its nominal voltage and be of sufficient capacity and be so arranged as to supply automatically in the event of failure of either the main or the emergency source of electrical power for half an hour at least the following services if they depend upon an electrical source for their operation:
  1. the lighting required by Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(a) and Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(c). For this transitional phase, the required emergency electric lighting, in respect of the machinery space and accommodation and service spaces may be provided by permanently fixed, individual, automatically charged, relay operated accumulator lamps, and
  2. all services required by Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(c).(ii), Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(c).(iii), Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(c).(iv) and Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(c).(v) and Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(h) unless such services have an independent supply for the period specified from an accumulator battery suitably located for use in an emergency.

3.3 Starting arrangements

3.3.1 The requirements for starting arrangements are given in Pt 6, Ch 2, 3.4 Emergency source of electrical power in cargo ships of the Rules for Ships, which are to be complied with.

3.4 Prime mover governor

3.4.1 The requirements for prime mover governor are given in Pt 6, Ch 2, 3.6 Prime mover governor of the Rules for Ships, which are to be complied with.

3.5 Radio installation

3.5.1 The requirements for radio installation are given in Pt 6, Ch 2, 3.7 Sources of Energy for Radio installation of the Rules for Ships, which are to be complied with.

3.6 Accommodation units

3.6.1 The emergency source of electrical power in units carrying more than 50 persons, who are not crew members or passengers, is to comply with the requirements of Pt 3, Ch 4, 4 Additional requirements for the electrical installation.

3.7 Alternative sources of emergency electrical power

3.7.1 Where it is proposed that a dedicated emergency source of electrical power and its associated transitional source of power will not be provided, the installation is to meet the requirements of this sub-Section.

3.7.2 The main sources of electrical power are to be:
  1. separated and located in two or more compartments that are not contiguous with each other;
  2. self-contained and arranged to be independent such that each system can operate without recourse to the other main source(s) including power distribution and any associated converting equipment and control systems;
  3. arranged such that a fire or casualty in any one of the compartments will not affect the electrical power distribution from the other(s), or to the services required by Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4;

3.7.3 The arrangements in each compartment referred to in Pt 6, Ch 2, 3.7 Alternative sources of emergency electrical power 3.7.2 are to be equivalent to those under paragraphs Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.5.(a) and Pt 6, Ch 2, 3.4 Emergency source of electrical power in cargo ships 3.4.1 of the Rules of Ships, so that a source of electrical power is available at all times to the services of Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.

3.7.4 The generator sets forming the main sources of electrical power referred to in Pt 6, Ch 2, 3.7 Alternative sources of emergency electrical power 3.7.2, are to meet the provision of Pt 6, Ch 2, 1.10 Inclination of the unit 1.10.2, with each generator having sufficient capacity to meet the requirements of paragraph Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4, in each of at least two compartments.

3.7.5 The number and arrangements of generators is to allow for maintenance at sea of any one generator without affecting the ability to comply with Pt 6, Ch 2, 3.7 Alternative sources of emergency electrical power 3.7.2.

3.7.6 Starting arrangements of main sources of electrical power are to comply with the requirements of Pt 5, Ch 2, 9.5 Starting of the emergency source of power of the Rules for Ships.

3.7.7 The location of each of the compartments referenced in Pt 6, Ch 2, 3.7 Alternative sources of emergency electrical power 3.7.2 is to comply with Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.2 and the boundaries meet the provisions of Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.3.

3.7.8 Where these Rules specify that a service is required to be connected to both the main and emergency source of electrical power or is to be connected to the emergency switchboard, these services are to be served by at least two individual circuits from the separated main sources of electrical power with arrangements to transfer between the two sources. The supplies are to be separated in their switchboard and throughout their length as widely as is practicable without the use of common feeders, protective devices, control circuits or control gear assemblies, so that any single electrical fault will not cause the loss of both supplies.

3.7.9 Provision is to be made for periodic testing to demonstrate services required by Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4 can be supplied automatically following the loss of one main source of electrical power.

3.7.10 To demonstrate compliance with the requirements of Pt 6, Ch 2, 3.7 Alternative sources of emergency electrical power 3.7.2, Pt 6, Ch 2, 3.7 Alternative sources of emergency electrical power 3.7.3 and Pt 6, Ch 2, 3.7 Alternative sources of emergency electrical power 3.7.5 a risk assessment is to be carried out demonstrating that a single point failure such as a fire within a space would not render the systems incapable of supplying those services required in an emergency.

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