7.9.1 In addition to complying with 5.2, the main source of electrical power
should comply with the following:
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.1 The arrangement of the unit's main source of
power should be such that the services referred to in 5.1.1.1 can
be maintained regardless of the speed and direction of the main propelling
engines or shafting.
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.2 The generating plant should be such as to ensure
that with anyone generator or its primary source of power out of operation,
the remaining generator(s) will be capable of providing the electrical
services necessary to start the main propulsion plant from a dead
ship condition. The emergency generator may be used for the purpose
of starting from a dead ship condition if its capability either alone
or combined with that of any generator is sufficient to provide at
the same time those services required by 5.3.2.1
to 5.3.2.3.
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.3 For electrically self-propelled units the application
of 5.2.1.2 need only include for
propulsion sufficient power to ensure safe navigation when underway.
7.9.2 The main switchboard should be so placed
relative to one main generating station that, as far as is practicable,
the integrity of the normal supply may be affected only by a fire
or other casualty in one space. An environmental enclosure for the
main switchboard, such as may be provided by a machinery control room
situated within the main boundaries of the space, is not to be considered
as separating the switchboards from the generators.
7.9.3 In every unit where the total installed
electric power of the main generators is in excess of 3 megawatts,
the main busbars should be subdivided into at least two parts which
should normally be connected by removable links or other approved
means; so far as is practicable, the connexion of generators and any
other duplicated equipment should be equally divided between the parts.
Equivalent alternative arrangements should be permitted.