• Technology

Marine Standards

The marine standards set forth by the classification societies define acceptable distortion levels. Like the grid standards, these are not concerned with the harmonic current injection, but only with the resulting voltage distortion. This is logical on a marine vessel or offshore installation, the island configuration with generators. The table below details both total harmonic distortion limit and individual harmonic limit on the voltage for a number of major classification societies, namely DNV GL, ABS, RS and KR:

Classification SocietyTHDU limitIndividual harmonic limitReference
DNV GL
Det Norske Veritas /
Germanischer Lloyd
< 8 %  < 5 % Rules for classification: Ships (Oct. 2019)
Part 4, Chapter 8, Section 2, 1.2.7
ABS
American Bureau of Shipping
< 8 % < 5 % Rules for Building and Classing Steel Vessels (Jul. 2019)
Part 4, Chapter 8, Section 2, 7.21
BV
Bureau Veritas
< 8 % ≤ 15th: 5 %, then falling logarithmic to 1 % at 100th Rules for Classification of Steel Ships (Jan. 2020)
Part C, Chapter 2, Section 2, 2.4.2 
LR
Lloyd’s Register
< 8 % None of the harmonics above 25th shall exceed 1.5 %  Rules and Regulations for the Classification of Ships (July 2019)
Part 6, Chapter 2, Section 1, 1.8.3
RINA
Registro Italiano Navale
< 10 % ≤ 15th: 5 %, then falling logarithmic to 1 % at 100th  Rules for the Classification of Ships (Jan. 2020)
Part C, Chapter 2, Section 2, 2.2.2
CCS
China Classification Society
< 10 % ≤ 15th: 5 %, then falling linearly to 1 % at 100th Rules for Classification of Sea-Going Ships (Jul. 2018)
Part 8, Chapter 15.2.2.2
RS
Russian Maritime
Register of Shipping
< 10 % ≤ 15th: < 10 % 16th – 99th: falling logarithmic to 1 %
100th – 200th: < 1 %
Rules for the Classification and Construction of Sea-Going Ships (Jan. 2020)
Part XI, Section 2.2.1
KR
Korean Register
< 8 % < 3 % Rules for the Classification of Steel Ships (2019)
Part 6, Chapter 1, Section 8

Note that DNV GL, ABS and KR all have individual harmonic limit that is not dependent of harmonic order – which means that the maximum of 5 % of for example DNV GL applies equally at 5th harmonic as well as at 49th harmonic! Surely, 5 % is much more damaging at higher harmonic orders. CCS, BV, RINA and RS circumvents this by specifying a falling curve from 15th harmonic to 100th harmonic – linear curve for CCS and logarithmic for BV, RINA and RS. Also note that CCS specifies the curve until infinite harmonic order, which technically makes it impossible to determine compliance, as no instrument have infinite bandwidth!

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