5.3.1 Every unit should be provided with a main
source of electrical power which should include at least two generating
sets.
5.3.2 The power of these sets should be such that
it is still possible to ensure the functioning of the services referred
to in paragraph 5.1.1.1, except for power servicing drilling operations,
in the event of any one of these generating sets being stopped.
5.3.3 Where transformers or converters constitute
an essential part of the supply system, the system should be so arranged
as to ensure the same continuity of the supply as stated in paragraph
5.3.2.
5.3.4 A main electrical lighting system which
should provide illumination throughout those parts of the unit normally
accessible to and used by personnel should be supplied from the main
source of power.
5.3.5 The arrangement of the main lighting system
should be such that a fire or other casualty in the space or spaces
containing the main source of power, including transformers or converters,
if any, will not render the emergency lighting system under section
5.4 inoperative.
5.3.6 The arrangement of the emergency lighting
system should be such that a fire or other casualty in the space or
spaces containing the emergency source of power, including transformers
or converters, if any, will not render the main lighting system required
by this section inoperative.
5.3.7 The main source of electrical power should
comply with the following:
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.1 Where the electrical power can normally be
supplied by one generator, suitable load-shedding arrangements should
be provided to ensure the integrity of supplies to services required
for propulsion and steering as well as the safety of the unit. In
the case of loss of the generator in operation, adequate provision
should be made for automatic starting and connecting to the main switchboard
of a stand-by generator of sufficient capacity to ensure safe navigation
when underway and to ensure the safety of the unit with automatic
restarting of the essential auxiliaries including, where necessary,
sequential operations. The Administration may dispense with these
provisions where the power necessary to ensure the functioning of
the service referred to in paragraph 5.1.1.1, except for power servicing
drilling operations, is 250 kW or less.
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.2 If the electrical power is normally supplied
by more than one generator simultaneously in parallel operation, provision
should be made, for instance, by load shedding to ensure that, in
case of loss of one of these generating sets, the remaining ones are
kept in operation without overload to ensure safe navigation when
underway and to ensure the safety of the unit.
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.3 Where the main source of electrical power is
necessary for propulsion of the unit, the main busbar should be subdivided
into at least two parts which should normally be connected by circuit
breakers or other approved means; so far as is practicable, the connection
of generating sets and other duplicated equipment should be equally
divided between the parts.