5.3.1 Every unit should be provided with a self-contained
emergency source of electrical power.
5.3.2 The emergency source of power, the transitional
source of emergency power and the emergency switchboard should be
located above the worst damage waterline and in a space not within
the assumed extent of damage referred to in chapter
3, and be readily accessible. They should not be forward of
the collision bulkhead, if any.
5.3.3 The location of the emergency source of
power, the transitional source of emergency power and emergency switchboard
in relation to the main source of electrical power should be such
as to ensure to the satisfaction of the Administration that a fire
or other casualty in the space containing the main source of electrical
power or in any machinery space of category A will not interfere with
the supply or distribution of emergency power. As far as practical,
the space containing the emergency source of power, the transitional
source of emergency power and the emergency switchboard should not
be contiguous to boundaries of machinery spaces of category A or of
those spaces containing the main source of electrical power. Where
the emergency source of power, the transitional source of emergency
power, and the emergency switchboard are contiguous to the boundaries
of machinery spaces of category A or to those spaces containing the
main source of electrical power, or to spaces of zone 1 or zone 2,
the contiguous boundaries should be in compliance with 9.1.
5.3.4 Provided that suitable measures are taken
for safeguarding independent emergency operation under all circumstances,
the emergency switchboard may be used to supply non-emergency circuits,
and the emergency generator may be used exceptionally and for short
periods to supply non-emergency circuits.
5.3.5 For units where the main source of electrical
power is located in two or more spaces which have their own systems,
including power distribution and control systems, completely independent
of the systems in the other spaces and such that a fire or other casualty
in anyone of the spaces will not affect the power distribution from
the others, or to the services required by 5.3.6, the requirements
of 5.3.1 may be considered satisfied without an additional emergency
source of electrical power, provided that the Administration is satisfied
that:
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.1 there are at least two generating sets, meeting
the requirements of 5.3.15 and each of sufficient capacity to meet
the requirements of 5.3.6, in each of at least two spaces;
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.2 the arrangements required by 5.3.5.1 in each
such space are equivalent to those required by 5.3.8, 5.3.11 to 5.3.14
and 5.4 so that a source of electrical power is available at all times
to the services required by 5.3.6;
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.3 the location of each of the spaces referred
to in 5.3.5.1 is in compliance with 5.3.2 and the boundaries meet
the requirements of 5.3.3 except that contiguous boundaries should
consist of an "A-60" bulkhead and a cofferdam, or a steel bulkhead
insulated to class "A-60" on both sides.
5.3.6 The power available should 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. The emergency source of power should 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
for their operation:
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.1 For a period of 18 hours, emergency lighting:
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.1.1 at every embarkation station on deck and
over sides;
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1.2 in all service and accommodation alleyways,
stairways and exits, personnel lift cars, and personnel lift trunks;
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.1.3 in the machinery spaces and main generating
stations including their control positions;
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.1.4 in all control stations and in all machinery
control rooms;
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.1.5 in all spaces from which control of the drilling
process 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;
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.1.6 at the stowage position or positions for
firemen's outfits;
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.1.7 at the sprinkler pump, if any, at the fire
pump referred to in 5.3.6.5, at the emergency bilge pump, if any,
and at their starting positions;
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.1.8 on helicopter landing decks;
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.2 For a period of 18 hours, the navigation lights,
other lights and sound signals, required by the International Regulations
for the Prevention of Collisions at Sea, in force;
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.3 For a period of 4 days any signalling lights
or sound signals which may be required for marking of offshore structures;
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.4 For a period of 18 hours:
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.4.1 all internal communication equipment that
is required in an emergency;
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.4.2 fire and gas detection and their alarm systems;
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.4.3 intermittent operation of the manual fire
alarms and all internal signals that are required in an emergency;
and
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.4.4 the capability of closing the blow-out preventer
and of disconnecting the unit from the well head arrangement, if electrically
controlled;
unless they have an independent supply from an accumulator battery
suitably located for use in an emergency and sufficient for the period
of 18 hours;
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.5 For a period of 18 hours, one of the fire pumps,
if dependent upon the emergency generator for its source of power;
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.6 For a period of at least 18 hours, permanently
installed diving equipment, if dependent upon the unit's electrical
power;
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.7 On column-stabilized units, for a period of
18 hours:
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.8 For a period of half an hour:
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.8.1 power to operate the watertight doors as
provided by 3.6.4.1, but not necessarily
all of them simultaneously, unless an independent temporary source
of stored energy is provided;
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.8.2 power to operate the controls and indicators
required by 3.6.4.1.
5.3.7 The emergency source of power may be either
a generator or an accumulator battery.
5.3.8 Where the emergency source of power is a
generator it should be:
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.1 driven by a suitable prime mover with an independent
supply of fuel, having a flashpoint of not less than 43°C;
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.2 started automatically upon failure of the normal
electrical supply unless a transitional source of emergency power
in accordance with 5.3.8.3 is provided; where the emergency generator
is automatically started, it should be automatically connected to
the emergency switchboard; those services referred to in 5.3.10 should
then be connected automatically to the emergency generator; and unless
a second independent means of starting the emergency generator is
provided, the single source of stored energy should be protected to
preclude its complete depletion by the automatic starting system;
and
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.3 provided with a transitional source of emergency
power, as specified in 5.3.10, unless the emergency generator is capable
of supplying the services mentioned in 5.3.10 and of being automatically
started and supplying the required load as quickly as is safe and
practicable but in not more than 45 seconds.
5.3.9 Where the emergency source of power is an
accumulator battery it should be capable of:
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.1 carrying the emergency load without recharging
while maintaining the voltage of the battery throughout the discharge
period within plus or minus 12% of its nominal voltage;
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.2 automatically connecting to the emergency switchboard
in the event of failure of the main power supply; and
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.3 immediately supplying at least those services
specified in 5.3.10.
5.3.10 The transitional source or sources of emergency
power, where required by 5.3.8.3, should consist of an accumulator
battery suitably located for use in an emergency, which should operate
without recharging whilst maintaining the voltage of the battery throughout
the discharge period within plus or minus 12% of its nominal voltage,
and be of sufficient capacity and so arranged as to supply automatically,
in the event of failure of either the main or the emergency source
of power, the following services for half an hour at least if they
depend upon an electrical source for their operation:
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.1 the lighting required by 5.3.6.1 and 5.3.6.2.
For this transitional phase, the required emergency lighting, in respect
of the machinery space and accommodation and service areas, may be
provided by permanently fixed, individual accumulator lamps which
are automatically charged and operated;
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.2 all essential internal communication equipment
required by 5.3.6.4.1 and 5.3.6.4.2; and
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.3 intermittent operation of the services referred
to in 5.3.6.4.3 and 5.3.6.4.4,
unless, in the case of 5.3.10.2 and 5.3.10.3, they have an independent
supply from an accumulator battery suitably located for use in an
emergency and sufficient for the period specified.
5.3.11 The emergency switchboard should be installed
as near as is practicable to the emergency source of power and, where
the emergency source of power is a generator, the emergency switchboard
should preferably be located in the same space.
5.3.12 No accumulator battery fitted in accordance
with this requirement for emergency or transitional power supply should
be installed in the same space as the emergency switchboard, unless
appropriate measures to the satisfaction of the Administration are
taken to extract the gases discharged from the said batteries. An
indicator should be mounted in a suitable place on the main switchboard
or in the machinery control room to indicate when the batteries constituting
either the emergency source of power or the transitional source of
power, referred to in 5.3.9 or 5.3.10, are being discharged.
5.3.13 The emergency switchboard should be supplied
in normal operation from the main switchboard by an interconnector
feeder which should be adequately protected at the main switchboard
against overload and short circuit. The arrangement at the emergency
switchboard should be such that the interconnector feeder is disconnected
automatically at the emergency switchboard upon failure of the main
power supply. Where the system is arranged for feedback operation,
the interconnector feeder should also be protected at the emergency
switchboard at least against short circuit.
5.3.14 In order to ensure ready availability of
emergency supplies, arrangements should be made where necessary to
disconnect non-emergency circuits automatically from the emergency
switchboard to ensure that power is available automatically to the
emergency circuits.
5.3.15 The emergency generator and its prime mover
and any emergency accumulator battery should be designed to function
at full rated power when upright and when inclined up to the maximum
angle of heel in the intact and damaged condition, as determined in
accordance with chapter 3. In no case need the equipment be designed
to operate when inclined more than:
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.1 25° in any direction on a column-stabilized
unit;
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.2 15° in any direction on a self-elevating
unit; and
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.3 22.5° about the longitudinal axis and/or
when inclined 10° about the transverse axis on a surface unit.
5.3.16 Provision should be made for the periodic
testing of the complete emergency system. This should include the
testing of automatic starting arrangements.