25 Jul 2024


Torque sensors measure to 10mNm and 30,000 rpm

Sensor Technology’s optical torque sensor can record brief transient torques accurately

A UK torque-sensing specialist has developed an optical rotary torque sensor that can measure values as small as 10mNm. This capability, combined with a 50kHz bandwidth, means that the sensor can record even the most fleeting of transient torques accurately.

Oxfordshire-based Sensor Technology expects its new TorqSense ORT230/240 sensors to be used for applications such as profiling the acceleration and deceleration of high-speed motors, controlling miniature machinery, and destructive testing of industrial equipment. They offer an alternative to Sensor Technology’s existing sensors based on surface acoustic waves that are ideal for low-torque or bandwidth applications.

The new sensors contain discs with segmented gratings positioned a short distance apart on a drive shaft so that opaque sectors on one disc partially obscure clear sectors on the other. When torque is applied to the shaft, it changes the alignment of the gratings, varying the light transmitted through to a detector. The transducer can detect torque bi-directionally, has a fast mechanical and electrical response, and offers low inertia.

The sensors do not need the brushes or complex electronics often found in traditional torque measurement systems, and can operate at speeds of up to 30,000 rpm. Full-scale torque can be specified in the range 10mNm to 100Nm. The non-contact operation ensures a long, reliable life. Sensor Technology is offering a lifetime warranty on the devices. The optical operating principle means they are immune from interference.

There are two versions of the sensors. The ORT 230 has fixed voltage or current analogue outputs – one for torque, another for speed or power. The ORT 240 has two user-selectable voltage or current analogue outputs – one for torque and the other for speed, power or peak torque – as well as digital outputs, including RS-232, CANbus and USB. Up to ten of these sensors can be connected via USB, and software can be used to change the transducer variables.

Both versions include diagnostics to report if torque, speed ratings or calibration data have been exceeded, while sensors monitor shaft temperatures for compensation and accuracy. Windows-based software is available to monitor, display and record the torque data.