7.9.1 In addition to complying with section 5.3,
the main source of electrical power should comply with the following:
-
.1 The arrangement of the unit’s main source
of power should be such that the services referred to in paragraph
5.1.1.1 can be maintained regardless of the speed and direction of
the main propelling engines or shafting.
-
.2 The generating plant should be such as to ensure
that with any one generator or its primary source of power out of
operation, the remaining generator or generators 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 paragraphs
5.4.6.1 to 5.4.6.4.
-
.3 For electrically self-propelled units the application
of paragraph 5.3.2 need only include for propulsion sufficient power
to ensure safe navigation when underway.
-
.4 Where electrical power is necessary to restore
propulsion, the capacity should be sufficient to restore propulsion
to the unit in conjunction with other machinery, as appropriate, from
a dead ship condition within 30 min after blackout.
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
electrical power of the main generators is in excess of 3 MW, 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 connection of generators and any other
duplicated equipment should be equally divided between the parts.
Equivalent alternative arrangements should be permitted.