Case Study: Equipmake
High‑Performance Electric Motor Testing with the RS425 Torque Transducer
Background
Electric motors underpin an increasingly wide range of industrial and transport applications, where efficiency, power density, and reliability are tightly constrained by both regulatory requirements and commercial expectations. Manufacturers operating in this environment are under continual pressure to improve efficiency and validate performance to meet demanding standards and the needs of their customers.
As with traditional motors, accurate measurement of torque, speed, and power remains fundamental when assessing electric motor performance. From design and prototyping through to testing and optimisation, high-quality, repeatable measurements allow engineers to analyse performance with confidence and continue development on a sound technical basis.
The Client: Equipmake
Datum Electronics were approached by Equipmake, a UK‑based engineering company specialising in advanced electric powertrains, motors, and electrification solutions for industrial markets and specialist vehicles, including ultra-compact, high-performance sports cars.
Founded by Ian Foley, formerly Head of R&D at Lotus F1 and founder of Williams Hybrid Power, Equipmake works across modelling, simulation, mechanical and electromagnetic design, prototyping, and test, enabling development work to be completed and validated within constrained timescales.
Developing high‑speed, high power‑density motors exposes the limitations of load‑cell‑based torque measurement, driving the need for a more accurate and repeatable approach.
The Challenge
Equipmake were developing a highly power‑dense permanent magnet electric motor as part of their AMPERE research programme, targeting significant improvements in power‑to‑weight ratio over conventional designs. As development progressed, accurate characterisation of mechanical performance became increasingly important, particularly during high‑speed and transient testing, where motor and driveline designs operate across a wide range of torque and rotational speed.
Motor torque is the single most critical variable that characterises instantaneous mechanical performance. Previously, Equipmake used load cells to measure force at a fixed moment arm. In practice, this approach resulted in variable zero offset between tests, required frequent recalibration, and introduced error from the non‑symmetrical mass of the motor mounted to the test rig.
To measure only the torque transmitted through the driveshaft by the test motor, Equipmake decided to invest in a dedicated torque sensor solution that would provide stable, repeatable measurements without the need for constant recalibration. By eliminating the influence of motor weight and bearing friction, they would gain a more accurate reading of the motor’s output.
The Solution
Following a review of the project requirements, our team identified that a custom variant of the RS425 Contactless Torque Transducer was the most appropriate tool for the job. The Datum RS425’s compact build and separate rotor–stator construction allowed the sensor to be installed within the available space, while eliminating bearing friction – vital for high‑speed, high‑torque motor testing.
The sensor design also enabled the use of a free‑issued shaft from Equipmake’s existing driveline. This allowed the transducer to be fitted without cutting the shaft or introducing an inline assembly, avoiding additional components that could increase installation time, add mass, or introduce further sources of measurement error. This approach also simplified removal and re‑installation as the test programme progressed.
The system was supplied with a Datum Universal Interface, providing a local display of live torque and power data during testing. A wide range of digital and analogue output options allowed the torque measurement system to be integrated into Equipmake’s existing test setup with minimal additional configuration.
The Outcome
The implemented torque measurement solution provided Equipmake with stable, repeatable torque data across a range of test conditions, including high‑speed operation. By moving away from load‑cell‑based measurement and adopting non‑contact rotary torque sensors, the test setup eliminated the need for frequent re‑zeroing and reduced the influence of parasitic loads introduced by the test rig itself.
The Datum RS425 enabled accurate measurement directly at the motor output, while an additional M425 Torque Transducer was used within the test rig to measure torque downstream of the gearbox. This configuration allowed Equipmake to characterise drive losses and mechanical behaviour more effectively during development and optimisation activities.
As a result, Equipmake were able to focus on analysing motor performance with greater confidence in the underlying torque data, supporting ongoing development work without introducing additional complexity into the test process.
Learn more about Equipmake and their electric motors at equipmake.com.
RS425 Contactless Torque Transducer
The RS425 Contactless Torque Transducer is a non‑contact shaft torque sensor for inline installation in drivetrains and test rigs. Its bearing‑free, rotor–stator design with wireless telemetry enables accurate torque measurement at very high speeds without wear or frictional loading on the shaft.
Available with standard or fully customised shaft configurations, the Datum RS425 covers torque ranges from 3 N·m to 30,000 N·m and integrates seamlessly with Datum Link for real‑time monitoring and data capture across mobile and desktop platforms.
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