© Photo | Royal Caribbean Cruises Ltd.

Harmony on the high seas

Almost 3,000 EC fans provide for perfect cabin condi­tions on the world’s second-largest cruise ship. Active PFC tech­nology ensures that so many units can work together without prob­lems.

Quantum of the Seas is the queen of the ocean. The most expen­sive cruise ship in the world and a floating oasis for 4,180 passen­gers, it was launched in the summer of 2014. It is nearly 350 meters long and 41 meters wide. Enter­tain­ment features on board include a glass capsule on a swivel arm for panoramic views from a height of 90 meters, a climbing wall, bumper car rides, numerous restau­rants, a musical stage, a surf simu­lator and much more. Taru Lähteen­mäki, R&D manager at Koja, a Finnish supplier of air condi­tioning systems, says: “Vaca­tioners here have high stan­dards. For air condi­tioning too, of course. They expect the air to be at just the right temper­a­ture, no matter what climate zone the ship happens to be cruising through.”

Lots of power in a small space

Each cabin has its own air condi­tioning. Thus every passenger can set the temper­a­ture one prefers.

Each cabin has its own air condi­tioning, with which passen­gers can set the temper­a­ture they prefer. Together with the big EC blowers in the public rooms, 2,956 fans ensure a pleasant climate on board. Because of the salty and often trop­i­cally humid air at sea, the fans from ebm-papst have a special coating to protect them against corro­sion. Many of the ship’s rooms are in the inte­rior or have no windows that can be opened. Air exchange in most parts of the ship takes place only in the venti­la­tion system.

Quantum of the Seas needed to consume 20 percent less elec­tricity than its precursor ship. That was the require­ment.”
Taru Lähteen­mäki, R&D manager at Koja


Fan coil produc­tion line at Koja.

Jukka Blåfield, tech­nical manager at ebm-papst Finland, says: “A high rate of air exchange needs to take place in a limited space here.” One of the main chal­lenges for air condi­tioning on ships is the avail­able space. Lähteen­mäki agrees, saying: “On a cruise ship, every cubic centimeter counts. All of the space needs to be avail­able to the passen­gers or crew, so the elec­tronics has to take up as little space as possible. For these reasons and others, we chose the compact but powerful ebm-papst centrifugal EC fans with forward-curved blades for the cabins, and RadiPac centrifugal EC fans with back­ward-curved blades for the public areas.”

Quiet energy-savers

When the cruise ship oper­ator Royal Caribbean Inter­na­tional ordered “Quantum of the Seas,” one of its most strin­gent require­ments was: 20 percent less energy consump­tion than the precursor ship! That also applied for the air condi­tioning system. “The low energy consump­tion of the EC fans was an impor­tant reason for us to choose ebm-papst as our partner. The ship has over thou­sands of fans but only a few compres­sors, for example. If you want to achieve savings with air condi­tioning, the fans give you a huge amount of leverage,” Koja’s Lähteen­mäki says. “Besides that, the fans are extremely quiet. So here too, they fulfill the high stan­dards of the passen­gers.”

Relief for supply network


On a cruise ship, every cubic centimeter counts. So the on-board air condi­tioners have to be espe­cially compact.

But when over 5,000 EC fans are connected to the same gener­ator in the same network, so-called harmonics can lead to prob­lems in the supply network. To avoid these prob­lems, ebm-papst has devel­oped a solu­tion, a module that is inte­grated in the fan elec­tronics: active PFC (power factor correc­tion). The module filters out input current peaks with an elec­trical engi­neering trick that mini­mizes disturbing harmonic content. Jukka Blåfield summa­rizes: “Espe­cially in the closed system on board, that’s a huge advan­tage. The active PFC tech­nology allows the shipowning company to plan for a smaller gener­ator from the start, since they can assume a lower peak load. That saves money, weight and space. And the power cables for the fans only need to be half as thick as without active PFC. That makes the system even more compact.”

Active PFC

The chal­lenge: EC fans work with a perma­nent magnet motor, which receives pulsed input current that causes current harmonics. When many EC fans are connected in parallel, the harmonics strain the supply network and can result in increased losses due to reac­tive power. Even other devices in the system network can be nega­tively impacted.


The solu­tion: ebm-papst has devel­oped active PFC (power factor correc­tion). A module inte­grated in the fan elec­tronics converts the pulsed input current of the EC motors into a sinu­soidal current. Then the current is shifted so that it is in phase with the voltage. This signif­i­cantly reduces the harmonic content and mini­mizes the input current’s peak value. Elec­tricity consump­tion remains at an accept­able value.

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