Section 4 Hybrid electrical power system performance

4.1.1 To provide sufficient electrical power and dependability to supply the required essential services, habitability requirements and those services required to maintain the ship in a normal sea-going and operational state during defined operational conditions without recourse to the emergency electrical supply.

4.1.2 Damage and injury: To provide electrical systems and equipment with suitable protection under fault conditions to prevent the following:

1. injury to onboard personnel:
2. damage to the equipment itself; and
3. damage to equipment connected to it.

4.1.3 On ships with electric propulsion, to provide sufficient electrical power necessary for an effective and agreed level of propulsion power during all normal and reasonably foreseeable abnormal operational conditions.

4.2.1 For Hybrid Power notation the performance of the system is to be such that in the event of a single failure operation of the system may be interrupted but is to be recoverable to a defined state bounded by time and magnitude.

4.2.2 For Hybrid Power (+) notation the performance of the system is to be such that in the event of a single failure operation of the system is to be uninterrupted with any degradation of performance agreed between the designers and Owners.

4.2.3 The hybrid electrical power system performance targets in all modes of operation are to be defined and agreed between the designers and Owners.

4.2.4 The electrical system design maximum and minimum operating voltage and input frequency together with acceptable limits of excursions are to be specified by the system designer and are to be in compliance with the requirements of the Rules.

4.2.5 Specific consideration is to be given to time-based performance targets for systems in which stored electrical energy supplies any part of the ship’s main power demand.

4.2.6 Methods of verification of actual performance against targets are to be defined and are to cover all phases of the lifecycle.

4.3.1 The hybrid electrical power system dependability principles are to be defined and agreed between the designers and Owners consistent with the requirements for Hybrid Power or Hybrid Power (+) notation.

4.3.2 The principles are to cover defined operating modes, all normal and reasonably foreseeable abnormal operating and fault conditions and are to specifically consider the fault ride-through capability of the system.

4.3.3 The principles are to cover failures in active components of any of the sources, stores, consumers, distribution system and energy management forming the hybrid electrical power system. Such components may include, but are not restricted to, the following:

1. Prime movers (e.g. auxiliary engines);
2. Generators and their excitation equipment;
3. Gearing;
4. Pumps;
5. Fans;
6. Switchgear and controlgear, including their assemblies;
7. Thrusters; and
8. Valves (where power actuated).

4.3.4 Consideration is to be given to other enabling systems not part of the hybrid electrical power system whose failure or degradation could affect correct functioning of the hybrid electrical power system (e.g. lubrication, cooling and ventilation systems).

4.3.5 The continuity of supply to essential and emergency safety systems is to be maintained, in accordance with Vol 2, Pt 9, Ch 1 General Requirements for the Design and Construction of Electrotechnical Systems.

4.3.6 Arrangements are to ensure that the supply of essential services is not disrupted by the unavailability of the largest source of electrical power and are to be in accordance with a clearly described, documented and agreed redundancy design intent.

4.3.7 The size and rating of electrical energy stores is to be appropriate for the specified lifetime when subjected to in-service cyclic loading. Calculations supporting this assessment are to be provided to LR.

4.3.8 For Hybrid Power (+) notation, a hybrid electrical power system dependability assessment is to be undertaken and submitted to LR. The objectives of the assessment are to:

1. demonstrate the dependability of the system during all normal and reasonably foreseeable abnormal conditions; and
2. demonstrate that an appropriate level of dependability is achieved that is commensurate with that agreed between the designers and Owners.

The assessment shall be undertaken to a recognised standard that is acceptable to LR (e.g. IEC 60300-3-1, Dependability management Part 3-1: Application guide – Analysis techniques for dependability – Guide on methodology).

4.4.1 The main source of electrical power is to comply with the requirements of Vol 2, Pt 9, Ch 2, 4 Main source of electrical power.

4.4.2 Any type of source of electrical power as detailed in these hybrid electrical power system Rules may, subject to the approval of LR, be considered as having equivalent function to that of a generating set as described in the Naval Rules including, but not limited to, Vol 2, Pt 9, Ch 2, 4 Main source of electrical power.

4.5.1 Sources of electrical power not forming part of the ship's main source of electrical power may be used as an additional source of electrical power to supply electrical services required for normal operational and habitable conditions provided that:

1. The quality of power supplies meets the requirements of Vol 3, Pt 1, Ch 6, 6.2 Power quality and stability; and
2. Automatic arrangements are provided to start and connect within a period not exceeding 45 seconds one of the sources forming the main source of electrical power in the event of a single failure or the quality of power supplies exceeding limits.

4.6.1 The emergency source of electrical power is to comply with the requirements of Vol 2, Pt 9, Ch 2, 5 Emergency and alternative sources of electrical power.

4.6.2 Where it is proposed that a dedicated emergency source of electrical power and its associated transitional source of power will not be provided, the main source of electrical power and associated equipment is to meet the requirements of Vol 2, Pt 9, Ch 2, 5.5 Alternative sources of emergency electrical power 5.5.2.

4.7.1 Ships utilising an external source of power are to comply with the requirements of Vol 2, Pt 9, Ch 2, 8 External source of electrical power.

4.7.2 Arrangements for d.c. external sources are to comply with a recognised standard that is acceptable to LR.

4.7.3 An external source of power may be used to charge onboard stores of electrical energy. Details of any such arrangements and their interfaces to ship systems are to be provided for consideration by LR.

4.8.1 Ships with electric propulsion are to comply with the power requirements of Vol 2, Pt 4, Ch 5, 4.3 Power requirements.

4.8.2 Ships with electrically driven azimuthing thrusters are to comply with the power requirements of Vol 2, Pt 4, Ch 3, 7 Electrical systems.

4.8.3 Ships with optional notations for propulsion and steering redundancy are to comply with the power requirements of Vol 3, Pt 1, Ch 3, 3 Machinery arrangements.