generators and switchgear
Drive towards better shaft generators
Permanent magnet generator technology offers benefits for marine applications
W ith costs,
increasing recent
pressure trends
on have
been towards more integrated power generation systems using shaft generators in place of more traditional auxiliary generating sets, typically driven by constant-speed, four-stroke engines. These gensets require space for installation and generally run on marine diesel fuel rather than lower cost heavy fuel oil. As a result, shaft generator systems have become more common, taking power from the main propulsion train to generate electricity to supply ship electrical loads.
Frequency control equipment comes as an integrated part of the permanent magnet generator package (credit: The Switch)
Shaft generator systems are typically based on synchronous generators with electrical excitation, mechanically driven from the main propeller shaft and feeding power into the ship electrical system either directly or through a frequency converter. In many cases a gearbox will be required in the drive system, introducing its own losses. Alternatively, a direct connection can
Lloyd’s Register approves medium voltage switchgear for marine use
Lloyd’s Register has completed a General Design Appraisal for the Dutch company Eaton Industies’ Power Xpert UX range of switchgear, confirming that the range meets all requirements for application in ships and other offshore facilities. The company began processing orders for marine applications within weeks of approval being granted. “The marine and offshore sectors are very important to us, and we’re delighted we now have approvals that will allow our customers in these sectors to enjoy the benefits offered by one of our most popular ranges of MV switchgear,” said Mostapha Azzahimi, product manager voltage systems at Eaton.
for medium
All Power Xpert UX switchgear is now type-tested to the latest IEC 62271-200
60 I Marine Propulsion I April/May 2014
standards, with marine build versions having undergone additional testing including for resistance to damp heat, dry heat and cold. Inclination and vibration tests have also been successfully carried out. Products are also constructed with earthed metal partitions that fully segregate all major compartments. Type UX switchgear is equipped with Eaton’s latest range of IEC vacuum circuit breakers type W-VACi, which have also been type- tested to the same standards. The innovative design of Eaton’s UX switchgear originated from the earlier Unitole products which have been in service for over 40 years. The withdrawable vacuum- operated breakers are air insulated and available at ratings of up to 4,000A. Eaton has adopted a policy of using environmentally-
friendly technology and materials and the UX therefore avoids the use of potentially harmful SF6 gas insulation. Its construction is modular, allowing flexibility in panel combinations, and multiple panels can be used in installations.
At the heart of switchgear cabinet are the
busbar and circuit breaker compartments. Busbars are totally enclosed in an earthed metal compartment which vents upwards into the arc chamber at the top of the cabinet. This chamber can be extended if required and connections can also be provided for
venting gases outside
the
switchgear room. The busbars themselves are fully insulated along their entire length and tested for ratings up to 4,000A and 50,000A for 3 seconds.
www.mpropulsion.com
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