Vacon (Vaasa, Finland) has been successful in introducing a series of completely modular AC drives for marine applications. Used for stepless speed control of asynchronous motors, the Vacon NX series drives include both air and liquid cooled units within the power range of 7.5 kW to 3 MW rated at 400 - 500 and 690 V. The liquid cooling feature allows maximum cooling efficiency and extremely compact unit size. Experience from existing installations shows significant savings in space and operational economy.

The Vacon NX frequency converters are based on a completely modular design with separate control and power sections, and easily customised software. Both the air-cooled and liquid-cooled units incorporate identical control modules. The liquid cooled unit has an exclusively designed power section with aluminium cooling elements. Major benefits are the high cooling efficiency of up to 95 %, as the heat loss can be dissipated outside the installation area, low noise level, and a compact design that allows space savings of up to 80% compared with conventional air-cooled drives. For example, a liquid-cooled 500 kW unit measures 400 mm and the 1500 kW unit only 800 mm in width.

Consequently, the product has rapidly gained popularity in main propulsion, steering, winches, pumps, fans, and a number of other onboard systems. According to the company, Vacon-controlled steering systems have been selected for 37 new building and retrofit projects, a market traditionally dominated by hydraulic solutions. Mounted in an IP54 or higher enclosure, the drives can withstand severe environments and wide variations in temperature. They have a low noise level, as no fan or any additional air-conditioning or filtered ventilation systems are required – an obvious benefit when retrofitting vessels.