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how to make a shaft power meter? Answered

I need to measure the shaft power output of a small motor. How to do that? Most machine on the market are to measure large shaf power output, such as of a car or motorcycle engine. My power output is estimated to be about 2kW.

Any suggestion would be of help to me.

Thank you.



The simplest classic method, if you don't need continuous readings, is to put a metal drum on the output shaft, usually hollow, so it can hold water, and with a band wrapped round it to a weight. The friction on the drum (whose radius can be measured) is related to the weight, so a torque is exerted on the shaft. Measure shaft speed and you have all you need.

Another method, for a continuous process, would mount the motor in bearings, so that the motor can twist about its axis, A set of springs resist the motion, and a measurement of twist angle is proportional to torque. Calibration is against a series of weights, applied at known radius.

You need it to do some work. For example drive a generator dumping energy into a load - you measure current and voltage. You could do a torque measurement and derive from there, but I think electric easier.