2.3.1 A self-contained emergency source of electrical power shall be provided.
2.3.2 Provided that suitable measures are taken for
safeguarding independent emergency operation under all circumstances,
the emergency generator may be used, exceptionally, and for short
periods, to supply non-emergency circuits.Exceptionally is understood to mean conditions, while the vessel
is at sea, such as:
Unless otherwise instructed by the Society, the emergency generator
may be used during lay time in port for the supply of the ship mains,
provided the requirements of [2.4] are complied with.
2.3.3 The electrical power available shall 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.
2.3.4 The emergency source of electrical power shall be capable, having regard to starting currents and the transitory nature of certain loads, of supplying simultaneously at least the services stated in [3.6.3] for the period specified, if they depend upon an electrical source for their operation.
2.3.5 The transitional source of emergency electrical power, where required, is to be of sufficient capacity to supply at least the services stated in [3.6.7] for half an hour, if they depend upon an electrical source for their operation.
2.3.6 An indicator shall 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 electrical power or the transitional source of emergency electrical power referred to in [2.3.13] and [2.3.14] are being discharged.
2.3.7 If the services which are to be supplied by the transitional source receive power from an accumulator battery by means of semiconductor convertors, means are to be provided for supplying such services also in the event of failure of the convertor (e.g. providing a bypass feeder or a duplication of convertor).
2.3.8 Where electrical power is necessary to restore
propulsion, the capacity of the emergency source shall be sufficient
to restore propulsion to the ship in conjunction to other machinery
as appropriate, from a dead ship condition within 30 min. after
blackout.For the purpose of this requirement only, the dead ship condition
and blackout are both understood to mean a condition under which
the main propulsion plant, boilers and auxiliaries are not in operation
and in restoring the propulsion, no stored energy for starting the
propulsion plant, the main source of electrical power and other
essential auxiliaries is to be assumed available. It is assumed
that means are available to start the emergency generator at all
The emergency generator and other means needed to restore the propulsion are to have a capacity such that the necessary propulsion starting energy is available within 30 minutes of blackout/dead ship condition as defined above. Emergency generator stored starting energy is not to be directly used for starting the propulsion plant, the main source of electrical power and/or other essential auxiliaries (emergency generator excluded).
For steam ships, the 30 minute time limit given in SOLAS can be interpreted as time from blackout/dead ship condition defined above to light-off the first boiler.
2.3.9 Provision shall be made for the periodic testing of the complete emergency system and shall include the testing of automatic starting arrangements, where provided.
2.3.10 For starting arrangements for emergency generating sets, see Ch 1, Sec 2, [3.1].
2.3.11 The emergency source of electrical power may be either a generator or an accumulator battery which shall comply with the requirements of [2.3.12] or [2.3.13], respectively.
2.3.12 Where the emergency source of electrical power
is a generator, it shall be:
2.3.13 Where the emergency source of electrical power
is an accumulator battery it shall be capable of:
2.3.14 The transitional source of emergency electrical power where required by [2.3.12] item c), shall consist of an accumulator battery which shall operate without recharging while maintaining the voltage of the battery throughout the discharge period within 12% above or below its nominal voltage 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 services in [3.6.7] if they depend upon an electrical source for their operation.
2.3.15 Where the emergency and/or transitional emergency
loads are supplied from a battery via an electronic converter or
inverter, the maximum permitted d.c. voltage variations are to be
taken as those on the load side of the converter or inverter.
Where the d.c. is converted into a.c. the maximum variations are not exceed those given in Ch 2, Sec 2, Tab 6.
2.3.16 For the emergency source of electrical power in passenger ships, see Pt D, Ch 11, Sec 5.