Section 5 Electrical equipment

5.1.1 The electrical installation is to be designed, constructed and installed in accordance with the requirements ofPt 5, Ch 16, 5.2 Generating arrangements.

5.1.2 Where the thruster units are electrically driven, the relevant requirements, including surveys, of Pt 6, Ch 2 Electrical Installations are to be complied with.

5.2.1 Where a central power generation system is employed, the requirements of Pt 6, Ch 2, 2.3 Number and rating of generating sets are to be complied with.

5.2.2 The generating and distribution system is to be so arranged that after any single failure, steering capability can be maintained or regained immediately, and the effectiveness of the steering after such a fault will not be reduced by more than 50 per cent. This may be achieved by the parallel operation of two or more generating sets, or alternatively when the electrical requirements may be met by one generating set in operation, on loss of power, the automatic starting and connection to the switchboard of a standby set, provided that this set can restart and run a thruster with its auxiliaries.

5.2.3 The failure of one thruster unit or its control system is not to render any other thruster inoperative.

5.2.4 A single failure of generator/switchboard should not lead to failure of any other generator/switchboard.

5.3.1 Thruster auxiliaries and controls are to be served by individual circuits. Services that are duplicated are to be separated throughout their length as widely as is practicable and without the use of common feeders, transformers, converters, protective devices or control circuits.

5.4.1 Where the auxiliary services and thruster units are supplied from a common source, the following requirements are to be complied with:

1. The voltage regulation and current sharing requirements defined in Pt 6, Ch 2, 4.5 Alternating current service generators are to be maintained over the full range of power factors that may occur in service.

2. Auxiliary equipment and services are to operate with any waveform distortion introduced by converters without deleterious effect (this may be achieved by the provision of suitably filtered/converted supplies).

3. The thrusters should not influence the other essentials.