Rising demand for diesel-electric propulsion solutions is targeted by Scandinavian Electric Systems (SES) with significant investment in design, testing and packaging - Continuing growth in the diesel-electric propulsion market is anticipated by the Bergen, Norway-based marine electrical systems specialist SES, which aims to strengthen its status as a global player.
Electric propulsion system suppliers have seen their market horizons expand considerably in recent years as more and more designers and operators of mainstream, specialist and offshore tonnage value the economic and operational merits of such systems over traditional diesel-mechanical installations:
* improved operational flexibility
* higher reliability and redundancy
* better utilisation of machinery space
* lower noise and vibration
* reduced emissions
* enhanced manoeuvring
* reduced manning
* overall life-cycle cost savings.
Even better economic and performance benefits can be realised when electric propulsion is married with azimuthing podded propulsors, which release space in the hull otherwise taken by the propulsion motors, shaftlines and steering gear. Pods are becoming increasingly popular for tonnage ranging from offshore vessels to large cruise ships.
Advantages more widely appreciated
The growing success of electric propulsion reflects significant advances in power generation systems and AC drive technology, and a wider appreciation by operators of the advantages in overall economy, availability and environmental friendliness delivered by the central power station concept.
A central power station for supplying propulsive power and ship services embraces the following elements:
A number of diesel gensets rated to deliver all the electrical power required for propulsion, manoeuvring, pumps and ship services.
The number of gensets connected to the distribution network can be varied according to the power demand at any time, allowing the diesel prime movers to run at high efficiency.
A distribution system, which may be divided into medium voltage and low voltage networks, respectively supplying the high power electric consumers (such as main propulsion and thruster drives), and the smaller consumers.
A variable speed AC drive system comprising a propulsion motor and a frequency converter. The motor speed is controlled by the converter which alters the input frequency to the motor driving the propeller(s), thruster(s) or pod(s).
Substantial investment
"Cost-effective solutions target maximised operating profitability, reliability and safety ..."SES has invested substantially in new facilities to support the design, packaging and testing of diesel-electric propulsion systems based on AC-drives tailored for offshore supply, stand-by and anchor-handling tonnage, ferries, smaller cruise liners, fishing vessels, seismic research ships and other appropriate applications.
Over 2,000 marine electrical systems ranging in size from 300kW to over 2,000kW have been delivered by the company since 1984 for diverse projects worldwide, including offshore supply vessels, dry cargo ships and tankers, fishing and passenger vessels.
SES designs, assembles and tests low voltage marine electrical systems optimised for the application, based on generators up to 4,500kVA output and AC motors and drive systems with ratings up to 3,300kW. "Cost-effective solutions target maximised operating profitability, reliability and safety, with full compatibility ensured between all the system components," explains the company's president and CEO, Jan Berg.
From design to field support
"A complete service is offered -- from system conceptual design through equipment selection, packaging and supply to commissioning and field support," Mr Berg says.
A system package typically embraces AC motors, automatic star/delta and auto transformer-starters, frequency converters, generators and control systems.
In creating both general and tailored systems, SES uses automatic star/delta and auto transformer starters that are designed and produced in-house, and it also develops support systems and key electrical products. The company sources high performance AC motors, generators and frequency control products from strategic international partners who are leading specialists in their fields, notably:
Marelli Motori SpA of Italy, the only European rotating machine factory producing AC motors and generators under the same roof.
Vacon Oy of Finland, a world leader in frequency control products.
Close co-operation is also maintained with major suppliers of high quality instruments, transformers, capacitor banks and other electrical products required to produce systems combining optimised performance with cost-effectiveness and durability.
SES can deliver diesel-electric propulsion systems with 12-pulse, 18-pulse or 24-pulse frequency drives in air-cooled or water-cooled configurations.
Active front end drives are particularly suited to satisfying requirements for low harmonics levels (below 5 per cent) in systems.
The company is well primed to serve a market trend towards compact water-cooled drive systems.
Compact designs
More compact and efficient marine electrical machinery solutions are continually pursued by SES. Proving popular is a double-jacket water-cooled motor, with ratings from 500kW to 1,300kW, co-developed by SES with Marelli Motori.
The design is around 50 per cent more compact than conventional motors of equivalent power rating. Further development of the motor to ratings up to 1,800kW is planned, opening up wider opportunities in propulsion systems.
Water-cooled frequency converters used by SES are also 50-60 per cent more compact than competing products, contributing again to the creation of space-saving systems.
Recent investment by SES in advanced R&D, design and test facilities (detailed in the attached profile) underlines its commitment to supporting consultants, yards and ship operators worldwide in creating and supplying cost-effective diesel-electric propulsion systems optimised for the application.
