Finnish company The Switch, a supplier of permanent magnet (PM) machines for marine applications, has launched the PMM850M PM machine, designed as a compact, high-efficiency solution to help shipowners lower fuel consumption, reduce emissions and decrease operating costs.
Key advantages are said to be:
- Reduced fuel consumption thanks to high electrical efficiency.
- Lower COâ‚‚ and NOx emissions, supporting compliance with environmental regulations.
- Minimal maintenance requirements due to the brushless design and simplified cooling system.
- High reliability supported by a proven PM technology platform with more than 5 million operating hours and no failures causing vessel downtime.
- Compact footprint, enabling greater flexibility in vessel layout and installation.
- Quieter operation and compliance with increasingly strict airborne and underwater radiated noise regulations thanks to the absence of external cooling fans.
Designed for shaft generator and propulsion applications, the PMM850M targets vessels operating in the 500kW to 1.5MW power range, filling a gap at the lower end of The Switch’s PM machine portfolio. It addresses a market need for a smaller and more cost-efficient machine for vessels where even the PMM1000M may be too large to install.
Jussi Puranen, The Switch Product Line Director, Electric Machines, said: “We often see that space in the engine room is extremely limited, especially in vessels with narrow hull designs. Our goal was to develop a compact, cost-effective machine for the lower power end without compromising efficiency. By combining water-jacket cooling with our high power density machine design, we have created a solution that is extremely compact while still delivering excellent efficiency throughout the entire operating range. With recent volatility in energy prices, maximizing efficiency is more important than ever to minimize fuel consumption.”
As vessel electrification continues to advance, the PMM850M is considered particularly suited for smaller bulk carriers, product tankers and coastal trading vessels, specifically narrow-hulled shortsea ships where engine room space is often constrained. Demand is especially visible in regional markets with large fleets of smaller ships, such as Japan, where many coastal vessels have narrow hull designs.
A key feature of the PMM850M is its water-jacket cooling system, which removes the need for external cooling units, including fans and heat exchangers. Cooling water flows through a hollow channel integrated into the machine housing and connects to the vessel’s freshwater cooling system. This approach simplifies the overall mechanical design while reducing footprint and operating expenses.
Puranen added: “Without an external cooling unit, the machine becomes significantly more compact. It also eliminates cooling fans, which means fewer components to maintain and lower operating noise.”
The new machine is based on The Switch’s PM technology platform, built on more than 20 years of experience. PM machines are thought to deliver particularly strong performance at partial loads, where ships frequently operate. Compared with conventional induction or electrically excited machines, they typically achieve 2–4% higher electrical efficiency at the rated point – and more at partial loads. This helps reduce fuel consumption and associated GHG emissions.
Puranen said: “The main difference is that PM machines don’t require electrical power for magnetisation. In conventional machines, that power demand remains even when the load decreases, reducing efficiency. With PM machines, this loss is eliminated.”
Depending on the application, the PMM850M can be delivered with or without bearings. In addition, its modular design allows the axial length of the machine to be scaled up or down depending on the power rating, matching it perfectly to the customer’s application without oversizing. Final testing is scheduled for the second half of 2026, and first deliveries are expected to start soon after that.
With the latest addition of the PMM850M, The Switch PM machine portfolio now includes more than 70 variants enabled by a scalable platform, covering a power range from roughly 500kW to over 10MW. By extending its PM machine range into lower-power and space-constrained applications, The Switch aims to ensure that vessels of all sizes can benefit from the efficiency and reliability advantages of PM technology. PM machines are suited to modern electric propulsion architectures, where the high efficiency across a wide load range, combined with fast response and compatibility with variable-speed drives makes them suited for integration into shaft generator systems, PTI/PTO configurations and hybrid or fully electric propulsion architectures.
Image: The PMM850M joins The Switch’s portfolio of PM machines for shaft generator and propulsion applications (source: The Switch)
