Torque Sensor/calibration

[robs314]

Hello
I am building a generator dynamometer to test motors and using the motor output to give me the torque produced. I am happy with the linear relationship for torque, but i will need to calibrate this output.

I guess I could try using a torque arm with a load cell. This would be fine for measuring the braking torque, but will this calibration still hold true for dynamic operation too?
Another option is a torque sensor - does anyone know how expensive these things are? I have a feeling they are costly, so i was wondering how easy it would be to make one.

There's one method which uses a strain gauge attached to the shaft, and the flex in the shaft is correlated to a torque output, sent through a slipring around the shaft. What I want to know basically is, is it a project in itself to make one?

Thanks

[serbring]

Hello
I am building a generator dynamometer to test motors and using the motor output to give me the torque produced. I am happy with the linear relationship for torque, but i will need to calibrate this output.

I guess I could try using a torque arm with a load cell. This would be fine for measuring the braking torque, but will this calibration still hold true for dynamic operation too?



If you work on elastic material behaviour, it is valid for dynamic operations too. If you are working on a commercial shaft and it works on designed work conditions, it should be no matters. But if you want to design a new shaft, so you have to estimate the working loads and then you can try to design the shaft.


Another option is a torque sensor - does anyone know how expensive these things are? I have a feeling they are costly, so i was wondering how easy it would be to make one.



There's one method which uses a strain gauge attached to the shaft, and the flex in the shaft is correlated to a torque output, sent through a slipring around the shaft. What I want to know basically is, is it a project in itself to make one?

Thanks


there are two ways for doing it and it depends by the money and the application you need.
You can use a transponder power supplies by a normal battery. The problem is the system autonomy. In my application this it lasts 24 working hours with 9V battery, and I don't know precisely how much it costs.
As alternative you can use induced power supply system and in this way you haven't autonomy problems but the system is very expensive and it depends by the working conditions. A supplier has asked me 6000€.