Section 2 Main source of electrical power

2.1 General

2.1.1 The main source of electrical power is to include at least two generating sets and is to comply with the requirements of this Section, Pt 6, Ch 2, 2 Main source of electrical power of the Rules for Ships and IEC 61892-2:2012, Mobile and fixed offshore units – Electrical installations – Part 2: System design, Section 4 without recourse to the emergency source of electrical power.

2.2 Number and rating of generators and converting equipment

2.2.1 The requirements for the number and rating of generators and converting equipment are given in Pt 6, Ch 2, 2.2 Number and rating of generators and converting equipment of the Rules and Regulations for the Classification of Ships, July 2022, which are to be complied with where applicable. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

Note The requirements are applicable when a unit is changing its location (self-propelled or towed) or stationary engaged in its primary function (e.g. drilling, pipe-laying, production or lifting, oil storage).

2.2.2 Under normal operating and sea-going conditions, the number and rating of service generating sets and converting sets, such as transformers and semi-conductor converters, when any one generating set or converting set is out of action, are:

to be sufficient to ensure the operation of electrical services for essential equipment, habitable conditions. See Pt 6, Ch 2, 16.3 Power requirements 16.3.5 of the Rules and Regulations for the Classification of Ships, July 2022 for electric propulsion systems;
to have sufficient reserve capacity to permit the starting of the largest motor for essential services without causing any motor to stall or any device to fail due to excessive voltage drop on the system;
to be capable of providing the electrical services necessary to start the main propulsion machinery from a dead ship condition. The emergency source of electrical power may be used to assist if it can provide power at the same time to those services required to be supplied by Pt 6, Ch 2, 3 Emergency source of electrical power, see also Pt 6, Ch 2, 2.3 Starting arrangements 2.3.2.

2.2.3 Where the electrical power requirement to maintain the unit in a normal operational and habitable condition is usually supplied by one generating set, arrangements are to be provided to prevent overloading of the running generator, see Pt 6, Ch 2, 6.9 Load management. On loss of power there is to be provision for automatic starting and connecting to the main switchboard of the standby set in as short a time as practicable, but in any case within 45 seconds, and automatic sequential restarting of essential services, see Pt 6, Ch 2, 1.6 Definitions 1.6.2, in as short a time as is practicable.

Note Where the prime mover starting time will result in exceeding this starting and connection time, details are to be submitted for consideration.

2.3 Starting arrangements

2.3.1 The requirements for starting arrangements are given in Pt 6, Ch 2, 2.3 Starting arrangements of the Rules for Ships, which are to be complied with where applicable. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

2.3.2 Where the emergency source of electrical power is required to be used to restore propulsion from a dead ship condition, the emergency generator is to be capable of providing initial starting energy for the propulsion machinery within 30 minutes of the ‘dead ship condition’. The emergency generator capacity is to be sufficient for restoring propulsion in addition to supplying those services in Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(a), Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(b).(i) and Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(b).(ii), Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(c).(i) to Pt 6, Ch 2, 3.2 Emergency source of electrical power 3.2.4.(c).(v). See Pt 6, Ch 2, 9.1 General requirements 9.1.1 of the Rules for Ships for dead ship condition starting arrangements.

2.4 Prime mover governors

2.4.1 The requirements for prime mover governors are given in Pt 6, Ch 2, 2.4 Prime mover governors of the Rules for Ships, which are to be complied with.

2.5 Main propulsion driven generators not forming part of the main source of electrical power

2.5.1 The requirements for generators and generator systems having the unit’s propulsion machinery as their prime mover but not forming part of the unit’s main source of electrical power are given in Pt 6, Ch 2, 2.5 Main propulsion driven generators not forming part of the main source of electrical power of the Rules for Ships, which are to be complied with. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

2.5.2 In addition to the requirements of Pt 6, Ch 2, 2.2 Number and rating of generators and converting equipment 2.2.3, arrangements are to be fitted to start one of the generators forming the main source of power automatically should the frequency variations exceed those permitted by the Rules.