Magnet shaft generator passes bench test

Paul Boughton

The Switch, a specialist of megawatt-class permanent magnet (PM) machines and frequency converter packages for advanced wind and marine drive trains, has successfully tested its PM shaft generator in a rigorous bench test in Vaasa. The first pair in an order of four PM shaft generators is part of a complete system being delivered by WE Tech Solutions of Finland to Wallenius Lines of Sweden. The PMM 1000 direct-drive marine shaft generator certified by Lloyds marks the first of its kind to take advantage of PM technology, allowing ships to gain greater efficiency over the entire speed range. 

During the end of November in Vaasa, Finland, the first two of four PM shaft generators successfully passed the rigorous back-to-back bench test. Each machine weighs 18 tons without the shaft and features a nominal power of 1.5 MW and speed range of 0 to 100 rpm. Nominal speed is 80 rpm. 

“The efficiency performance during testing was an outstanding 97% over the entire speed range, even surpassing our expectations,” says Mika Koli, business development manager of Marine at The Switch. “What’s unique about our bench test setup is that we can immediately do full-power testing to check the efficiency across the entire speed range. In fact, we carried out extremely comprehensive testing to receive certification from Lloyds, one of the top authorities in the marine sector. This has indeed been worth the effort, because we strongly believe this product will be seen on many ships in the near future.”

The PMM 1000 direct-drive marine shaft generator will be located on the propeller shaft between the prime mover and the propeller. No bearings are needed. The generator rotor is connected to the propeller shaft with a shrink disk-type coupling. The Switch offers PMM 1000 shaft generators in various power ranges from 0.5 to 7 MW at speeds of 100 rpm to best adapt to various requirements. The shaft generator from The Switch will be delivered with the WE Drive variable frequency drive from WE Tech Solutions to allow the ship’s electrical network to be generated with the same high efficiency throughout the full speed range of the main engine.

“This is the next big thing in marine,” says Mårten Storbacka, managing director of WE Tech Solutions. “Over the past three years, we’ve been developing our solution together with The Switch and other close suppliers. The main advantage of this technology is that it significantly increases marine energy efficiency. Depending on how you calculate it, fuel savings are approximately 20-30%. Since this technology lowers the need for installed power on a ship, energy generation and weight are reduced significantly, thereby lowering fuel consumption and the need for maintenance.” 

Permanent magnet technology has been proven in numerous industries and under extremely harsh operating conditions to provide unmatched power density, energy efficiency, design flexibility and operational reliability. Now it is possible for ship builders and ship owners to gain from true fuel savings by upgrading to PM technology for shaft generators. 

The first four PMM direct-drive marine shaft generators will be delivered to the Wallenius 8000 PCTC, a post-Panamax high-efficiency Ro-Ro vessel new-build series being built in China. The first vessel is due for completion in Q4 2015. Additional orders have been placed by WE Tech for delivery to Terntank Rederi AS of Denmark and Torvald Klaveness of Norway. 

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