From installer to contractor to shipyard Danfoss VLT® expertise saves time and energy

Ulstein Verft shipyard and AF Offshore Aeron AS chose Danfoss VLT® drives to control the seawater cooling system, cargo delivery system and HVAC applications in their state-of-the-art subsea vessel, ‘Island Performer’. Danfoss were selected not just for the uncompromising quality, reliability and efficiency of their VLT® drives, but for their expertise during the installation and programming of the drives.

The height of technology for the ocean’s depths
‘Island Performer’ is the next generation subsea vessel from Ulstein Verft shipyard, with large accommodation, storage and lifting capacities. Built to provide offshore installation and construction services for subsea umbilicals, risers and flowlines and to perform riserless light well intervention and inspection, maintenance and repair works, she is able to perform operations at depths down to 3,000 meters. Precision, safety and efficiency are obviously paramount in this extremely challenging working environment, but personnel comfort has also become increasingly important. The role of air-conditioning plays an increasingly important role.

A history of successful co-operation
Ulstein and AF Offshore Aeron AS have had a long term-relationship of more than 10 years and are extremely satisfied with the Danfoss products and technical support.

Around 10 to 15 years ago, all motor were DOL driven. Ulstein were among the first to use drives for cargo pumps on PSV’s - now they have started using drives for ballast water and seawater cooling systems. Danfoss drives have consistently delivered to specifications and expectations – and continue to be used in cutting edge vessels such as ‘Island Performer’.

Danfoss VLT® drives save energy
By using Danfoss VLT® drives in the seawater cooling and air-conditioning systems, energy consumption on board is reduced. By reducing the speed of the seawater cooling pumps, cavitation in the cooling system is also reduced. 

“Seawater cooling systems are normally designed for 32° C seawater temperatures. But for vessels such as ‘Island Performer’, which can frequently operate in cooler areas such as The North Sea, this is over-dimensioned when it comes to cooling capacity,” says Frank Brandal, Production Coordinator at Ulstein Verft. 

“By using Danfoss VLT® drives, pumps operate consistently at their optimum level for cooling, to save energy. The same principle applies when using these drives in air-conditioning systems,” adds Odd Willy Larsen, Project Director at AF Offshore Aeron AS.

Air-conditioning improves productivity
‘Island Performer’ has been developed and built according to the latest international regulations in which comfort is a key issue. She carries the DNV GL class notation Comfort Class and ‘COMF-V1, which ensures that noise and vibrations are kept at minimum.

It is a known fact that a well dimensioned HVAC system is the key to a good indoor environment onboard a ship. Fresh air is vital to both personnel and machinery – feeling good improves productivity. By using small-footprint, Danfoss VLT® drives in their latest high-speed systems, AF Offshore Aeron AS meets the requirements for less space consumption onboard ships and eliminates noise and vibration problems. 

“Danfoss VLT® drives are small and compact units which are easy to install and program. The Danfoss product range is excellent and price competitive,” says Odd Willy Larsen, Project Director at AF Offshore Aeron AS.

Saves maintenance costs, reduces service
Danfoss VLT® drives have also been used in the ‘’Island Performer’s’ cargo delivery systems, where their ability to optimize the flow or pressure to the capacity of the rig or vessel receiving the cargo. This is important, as the vessel’s own cargo system has a potentially high capacity, while those of the receiver may be considerably smaller.

“We have not yet calculated how much energy we save, as circumstances vary from operation to operation and also where in the world the vessels operate. But what we can say for certain is that the maintenance costs for the ship owner have gone down and service intervals have increased.” says Odd Willy Larsen.

Expert installation advice saves working hours
Correctly installing and programming the VLT® drives is vital to achieve maximum performance and energy savings. Danfoss Sales Engineer, Odd Roar Buttingsrud, spent a full day at the yard assisting Ulstein engineers to program the drives, while guiding them on how to install the drives properly when it came to the grounding and shielding of motor cables.

“This is of great value to us,” says Frank Brandal, Production Coordinator at Ulstein Verft. “We are really able to save a lot of working hours when Danfoss teaches us how to program the drives by using MCT 10 – and it’s always easy to contact Danfoss if you need help or assistance by phone,” he concludes.