Section 3 Quality of power supplies – ELS notation
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Naval Ships, January 2023 - Volume 2 Machinery and Engineering Systems - Part 9 Electrotechnical Systems - Chapter 1 General Requirements for the Design and Construction of Electrotechnical Systems - Section 3 Quality of power supplies – ELS notation

Section 3 Quality of power supplies – ELS notation

3.1 General

3.1.1 Where electrical power for the designated loads in the System Design Description of Vol 2, Pt 9, Ch 1, 1.4 Documentation required for design review 1.4.5, is provided in accordance with the applicable provisions of a relevant and acceptable naval standard, such as STANAG 1008, the class notation ELS may be assigned.

3.2 General requirements

3.2.1 The electrical system is to be stable in all operating profiles defined in accordance with the System Operational Concept .

3.2.2 The quality of the power supplies for the loads listed in the System Operational Concept is to comply with the standard, in place of the limits specified by Vol 2, Pt 9, Ch 1, 2.1 Quality of power supplies (QPS) 2.1.2 . This level of quality is to be present at the point where the load is connected to the electrical power system.

3.2.3 Where the main generation and the distribution power supplies are also required to comply with the standard, the main generation and distribution system is to be of an insulated type in compliance with Vol 2, Pt 9, Ch 3, 4.4 Insulated distribution systems. See also Vol 2, Pt 9, Ch 3, 4.5 Earthed distribution systems 4.5.7.

3.2.4 A systematic procedure incorporating verification and validation methods is to be used to ensure successful implementation of the defined standard. A quality plan is to be submitted that describes this procedure along with the results of the design validation providing:

  • details of any power system analysis software and the input data used;
  • a transient stability analysis, unless the generator and load characteristics indicated by Vol 2, Pt 9, Ch 2, 6.4 Generator control are shown to be representative of the system under consideration;
  • a harmonic distortion analysis, if the sum of loads that distort the current waveform is greater than 1% of the short circuit power of the generating capacity.

3.2.5 Where a transient stability analysis demonstrates that the defined standard requirements can be satisfied by generator control requirements different to those specified by Vol 2, Pt 9, Ch 2, 6.4 Generator control , these may be accepted as equivalent to the Rules.

3.2.6 Unless it can be satisfactorily shown by the design verification and validation process that the requirements of the defined standard can be met, then measurements are to be taken as specified in Vol 2, Pt 9, Ch 12, 1.2 Trials 1.2.8.


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