Magnetics Business & Technology - Summer 2018 - 24

CASE STUDY
Magne c Transmissions Increase Lifespan of
Oﬀshore Wind Farms
By Zach Conrad, Multiphysics Marketing Engineer, COMSOL
Inc.
At Sintex, multiphysics simulation is used to develop and analyze
non-contact magnetic couplings. Such systems will offer significantly improved reliability, medium separation, and finding crucial
roles in offshore wind turbines and chemical pumping applications.
Whether it's an automotive engine, a wind turbine, or something
as straightforward as a wristwatch, torque conversion and the
transmission of rotational power are important for various technological applications.
Traditionally, transmission is achieved through a series of collinear mechanical gears or shafts that transfer torque and thus
power. But mechanical transmission has inherent limitations,
namely a susceptibility to friction, wear and tear, and overload
because of the continual contact. As the scope of technology
continues to expand into more hostile and unforgiving environments, these limitations can be of extreme detriment. In places
of limited accessibility and harsh conditions, replacing failed
transmissions is a challenging and tremendously costly task.

Power Transfer without the Friction
Engineers at Sintex have developed an innovative alternative
that provides robustness and reliability: magnetic couplings. The
essence of these couplings is that the power transfer is achieved
via magnetic forces, rather than mechanical forces, therefore
removing contact and wear and tear and drastically improving the
lifetime of the transmission system.
Power is transmitted through a torque coupling between concentric arrays of permanent magnets (Figure 1). A power source
causes one drive to rotate, while the coupling of the magnetic
fields between the drives causes the other to rotate with the
same speed. This system allows rotational power to be transferred just as in mechanical transmissions but without the friction

Magnetics Business & Technology * Summer 2018

Figure 1: Schematic of a magnetic coupling
and risk of overload. If the torque transferred from the motor is
too high, the coupling will limit excessive amounts from being
applied to the shaft. This limit prevents the shaft from undergoing
torque values greater than what it was designed for, thus assuring operation in its intended conditions.
Sintex's noncontact magnetic couplings are ideal for their
customers in offshore wind turbines and industries that employ
complex pumping systems. Offshore wind farms are becoming
increasingly integral with their generation of electricity, but require high levels of reliability in their components because of how
difficult these parts are to repair. In individual turbines, magnetic
couplings transfer energy from the motor to water pumps that
cool the electrical components 24 hours a day. As these offshore
systems involve such remote installations, preventative maintenance or repairs are burdensome and expensive, making the reliability of magnetic couplings invaluable. In addition, the air gap
between drives easily accommodates the insertion of a separator
can (Figure 2), allowing for media separation and closed systems
for use in chemical and food industries. Pumping systems that
are completely devoid of leakage are critical for the transport,
mixing, stirring, and grinding of chemicals and toxic materials.

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