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How to measure torque of a motor? | Torque Testing Stand

Application Summary

How to measure torque of a motor? 

A relatively simple method to estimate electrical motor torque is to measure its electrical power input, the voltage and the current in the power line driving the motor. For most motors, torque is directly proportional to the current and can be derived from it by knowing shaft speed and motor efficiency. This is considered an indirect measurement of torque since it is not the true mechanical torque but instead a relation from electrical power quantities to a theoretical and estimated torque value.

Another alternative and indirect method is to create a transversal arm attached to the motor housing using a known arm length. Let the whole motor housing outside case run freely along the attached arm. The arm tip can then be placed on a load cell. The torque can now be measured using a the load cell measurement and the arm length.

However, for a precise and accurate shaft output torque measurement, a rotary torque sensor is the recommended method. 
Rotary Torque Sensors are frequently used as auditing tools for motor torque testing stand in motors, power tools, turbines, and generators.

Products in Use

One Rotary Torque Sensor (TRS Series) paired with Instrumentation (IPM650, IHH500 or USB520).

how to measure torque of a motor torque testing stand
How it Works
  1. FUTEK's TRS Series is an effective tool for motor torque testing/auditing, feedback control, monitoring torque, and analyzing the efficiency of test stands.

  2. In this application, the TRS Rotary Motor Reaction Torque Sensor is coupled between an eddy brake and motor.

  3. As the motor rotates, the TRS Motor Torque Sensor measures the torque produced by the motor in response to the load generated by the brake.

  4. FUTEK developed certain models of the TRS Series with built-in encoders. These encoders measure the angle/speed produced during this test.

  5. Torsion measurements can successfully be monitored on a digital display, such as FUTEK's IPM650 Panel Mount Display or IHH500 Intelligent Hand Held Display, or streamed to a PC using FUTEK's USB520.

  6. The USB520 is the ideal data exchange solution for systems that require translation of rotary torque encoder readings, such as angle and speed. Its compact and robust design also makes the USB520 fitting for this type of industrial application.

  7. Applying FUTEK's SENSIT™ Test and Measurement Software to this test platform will allow the operator to live graph and data log the results.

All FUTEK application illustrations are strictly conceptual. Please Contact Us with questions.
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