Ships and offshore drilling units rely on electrical installations for safe and reliable operation. The installations may be subjected to very harsh conditions and environmental or chemical hazards, but should still continue operating. To do so they must meet stringent standards.
IEC TC (Technical Committee) 18: Electrical installations of ships and of mobile and fixed offshore units, prepares such standards for the maritime sector; its SC (Subcommittee) 18A deals specifically with standards for electric cables. An IEC Committee of Action, meeting in Bellagio (Italy) in 1927, identified a need for standardization of electrical installations in ships. This led to the establishment of a specific Advisory Committee to work in this domain. This Committee subsequently became TC 18.
The provision of electricity is vital to the operation of any vessel and continuity of supply is taken for granted while the crew, sometimes with only the most rudimentary electrical training, must be able to operate a power station with an output of anywhere between a few hundred kilowatts to over 100 MW. At the1986 meeting of TC 18 in Bergamo, Italy, it was decided to expand the TC’s scope to cover electrical installations on board fixed and mobile offshore oil and gas exploration units, as it was felt that the existing standards for ships were not necessarily appropriate to these environments. In 1988 it was agreed that a separate standard should be prepared to cover offshore installations.
Leading global adoption
IMO (International Maritime Organization), the United Nations agency with special responsibility for the safety and security of shipping, acknowledging the IEC's expertise, established a formal relationship with TC 18 to collaborate in the field of electrical systems on ships and offshore units.
A central part of IMO activity is to adapt the SOLAS (Safety of Life at Sea) Convention to changes in technology and safety requirements as they occur. This convention applies to all commercial international seagoing ships of 500 gross tonnes and above. Rather than opting to develop their own standards, most of the industry's bureaus or registers of shipping, such as the ABS (American Bureau of Shipping), Bureau Veritas, DNV (Det Norske Veritas), Lloyd's Register, the Korean Register of Shipping and the Russian Maritime Register of Shipping, to name just a few, rely on IEC International Standards as their preferred choice.
IEC 60092, the current series of International Standards for Electrical installations in ships, the first edition of which was published in 1957, is referenced in the SOLAS Convention. Thus all the standards in the series are used extensively at a global level. Both the standards for ships and those for mobile and fixed offshore installations are implemented worldwide by naval architects, marine engineering design and consulting companies, and all industries involved in the shipbuilding and related sectors.
They are used for supporting regulations and as the basis for contracts, and often replace the statutory authority documents.
All installations, including fire safety
TC 18 standards cover all types of equipment and installations used on board ships and in mobile and fixed offshore installations. Previously, the standards gave specific requirements for equipment such as switchboards, rotating electrical machines, transformers and galley (kitchen) equipment. Today, reference is, as far as possible, given to existing equipment standards issued by the TCs of relevant products, and only those additional or alternative features required for use in a ship or offshore environment are given in TC 18 standards.
A major project underway within TC 18 aims at reducing the number of standards and at updating others to reflect the fast-changing pace of current marine technology.
Coping with increased power and computing
As the electrical power requirements of modern ships continue to increase, there is a tendency to introduce higher operating voltages for power consumers, propulsion and machinery auxiliaries.
Currently the most important technical developments in the shipbuilding and offshore industry relate to the increasing extensive use of computer hardware and software control and monitoring systems for machinery and the introduction of additional and more sophisticated passenger/crew safety systems. The latter include addressable fire alarm and low level lighting systems, as well as passenger and crew address systems.
Problems are already being seen with the increased complexity of systems on board vessels, which has outstripped the ability of shipbuilders and operators to understand and deal with the systems installed.
Fire has always been a major threat to mariners: they have nowhere to escape to and no external aid is available. Today there is a growing understanding not only of the dangers of fire but also of the consequences of the spread of fire and of the risks associated with smoke. For these reasons, special attention is paid to characteristics such as flame retardancy, fire resistance, smoke emission, toxicity, corrosivity and halogen-free materials for both electrical equipment and cables.
Bigger, faster ships on the horizon
The current types of ship will continue to exist but will do so in parallel with new, larger and more efficient container and passenger ships. High-speed vessels of a variety of types and sizes will also be introduced, accompanied by requirements for a reduction in weight of all installed machinery and systems, including electrical installations.
Energy efficiency aimed at reducing greenhouse gas emission from ships is currently under discussion within IMO. This may lead to more efficient power generation and distribution systems, so TC 18 is closely monitoring developments there.
The increase in the size of vessels and of the installed electrical load is leading to the use of higher voltage systems. A return to electric propulsion systems coupled with advances in solid state power devices and the need for VSDs (variable speed drives) for auxiliary machinery has led to stricter control of EMC (electromagnetic compatibility).
The problems caused by electromagnetic interference have grown in importance due to the increased use of computer hardware and software control and monitoring systems. This is reflected in the development of standards for VSD cables and the initiation of an extensive updating of the TC’s EMC standard, as well as on-going work on a new standard to cover EMC for vessels with non-metallic hulls, which is expected to be issued in 2014.
Ship to shore connections cutting pollution in ports
In order to cut heavy fuel consumption and reduce greenhouse gases, such as CO2 and NOx(nitrogen oxide), as well as noise from ships while in port, today there is a tendency to provide electrical power from shore to ships while in port. In 2009, TC 18 issued a PAS (publicly available specification), IEC 60092-510, Electrical installations in ships – Part 510: Special features – High-voltage shore connection systems, giving requirements for such shore connections.
This standard has now been further developed in cooperation with ISO (International Organization for Standardization) TC 8: Ships and marine technology, and IEEE (Institute of Electrical and Electronics Engineers) Industry Applications Society Petroleum and Chemical Industry Committee, into an International Standard, IEC/ISO/IEEE 80005-1, Utility connections in port – Part 1: High Voltage Shore Connection (HVSC) Systems – General requirements. Publication of this standard is expected in the second quarter of 2012.
There has also been collaboration with IEC SC 23H: Industrial plugs and socket-outlets, which has prepared standards for plugs, socket-outlets and ship couplers for HVSC systems.
More environmental issues
Environmental issues are becoming more important with the rise in public and political concern over pollution and global warming. This is having an impact on national and international legislation and on the standards developed to support these.
TC18 is primarily concerned with the installation of electrical equipment and so the end of life disposal of installations on board the ship or offshore unit is beyond its scope. However, TC 18 is aware that laws in different countries focus on the restrictions on the usage of hazardous materials, substances and processes. The committee is therefore conscious of the need to protect the environment and thus strives to ensure that the materials employed in the installations are environmentally friendly and cause the minimum of pollution possible.
The shipping industry is also experiencing a shift towards electric and hybrid propulsion systems. This started in the cruise ship industry and is due primarily to the development of power electronics.
Hybrid solutions use a combination of diesel engines or gas turbines, generators, batteries and motors to drive the propulsion system; they will require improved and modified standards. A move to variable speed auxiliary drives is also being seen for the same reasons. The standard for electrical propulsion is now being updated and a revised standard is expected in 2013..
Mobile and fixed offshore installations
The first standard in the IEC 61892 series for offshore installations was issued in 1997. The series consists of 7 publications covering general requirements, system design, equipment, choice and installation of cables, mobile offshore units, installation requirements and hazardous areas. It was completed in 2007.
In the offshore industry there is a trend to use VSDs, instead of gas turbines, to drive large turbines and compressors. The power requirement of a production installation can be in excess of 60-70 MW. Normally, the power is supplied locally by gas turbine-driven generators, but depending on distance from shore and availability of power in the grid, some installations are supplied from shore via a cable. Depending on the distance and power requirement, either a.c. or d.c. may be used for supply from shore.
The offshore series is a referenced document in the IMO MODU Code (Code for the construction and equipment of mobile offshore drilling units). The standards are currently only referenced by 3 national regulatory bodies but are widely used by oil companies and major drilling contractors.
Even if the electrical system is an important part of a ship or an offshore unit, it is only one of a number of systems required for full functionality of the ship or offshore unit. This means that collaboration with other standardization bodies such as ISO or IEEE is necessary in addition to close cooperation with IMO.
As well as relationships with other IEC technical committees, TC 18 has liaisons with ISO TC 8: Ships and marine technology, ISO TC 67: Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries and ISO TC 188: Small craft.
Given the extent of its scope and the expansion and fast-changing pace of the shipping and offshore sectors, TC 18 has a busy schedule ahead, updating a number of International Standards and preparing new ones.