Non-contact torque sensors
from Sensor Technology are
used in the development of
commercial-scale in-stream tidal
turbines produced by OpenHydro.

The company uses the sensors, which
are based on surface acoustic wave
(SAW) technology, to accurately
measure rotational speed and
frictional forces in a simulator for
the turbine bearings.

The simulator allows engineers to
determine how frictional forces in
bearings vary with different loads
and rotational speeds. Central to this
is the measurement of torque in a
shaft from the motor that drives the
bearing under test. TorqSense RWT3
series sensors provided a solution.

The units depend on SAW
transducers that comprise two thin
metal electrodes, in the form of
interlocking ‘fingers’, on a piezoelectric
substrate such as quartz.

Since the transducers operate at
radio frequencies, it is easy to couple
signals to them wirelessly. Hence
TorqSense sensors can be used on
rotating shafts, and can provide data
continuously without the need for
brushes and slip rings.

OpenHydro uses the RWT320
sensor in conjunction with Sensor
Technology’s TorqView software.