The Switch installs 100th PMM
The company also has a backlog of orders for large LNG and LPG carriers where PMMs have become the standard choice thanks to their reported improved efficiency in partial load/slow-speed applications.
“Using PMMs for electrical power generation is a game-changer in terms of greater efficiency, reliability and flexibility especially where slow steaming is a desired function,” said head of product line, electric machines, Jussi Puranen.
Electrically excited synchronous generators connected to the ship’s grid have typically replaced separate auxiliary gensets in generating onboard power but even these have their limitations with fixed speeds and the need for complex additional kit.
Step in PMM generators, which are increasing in popularity in shipping since their invention more a century ago. They feature Neodymium magnets that don’t require external energy resulting in a two to three per cent higher efficiency across the entire operating range. Secondly, PMMs are more compact and mechanically simpler in construction than EESGs, meaning greater long-term reliability, less maintenance and no need for additional kit.
PMMs are also said to offer low inertia and weight thanks to their simple rotor construction, making them lighter to handle and easier to accommodate. Finally, coupling a PMM with a frequency converter gives the maximum amount of freedom as engine and propeller can be optimised separately depending on load conditions.
