Motor testing advice.

[Cadbhoy]

Hello people,

I need to analyse a bunch of AC induction motors from 0.25kw - 2kW.

Does anybody know if there is an off-the-shelf Generator device I can hook up to create a load and get some data under different loads?

I guess I'm after a brake/generator device of some kind.

I've already set up test rigs to do reliability testing using Labjack gear.

Any advice greatly appreciated. I usually sub contract this work out but it's getting more and more difficult finding somewhere that's interested.

cheers
CB

 

[hayesaaron54]

Cadbhoy

If you're interested in Jobbing out your motor testing we are interested and available for you. We're located in Seatle,Wa.

 

[Skogsgurra]

It depends what you need to test. I have used a large flywheel as the load and then DOL started the motor. Works quite well for small motors like yours. If necessary, I also reverse it a few times. With a moderately fast recorder or scope plus a CT and perhaps an analogue tacho generator to record speed, you can get lots of information out of such a test.

But I doubt that LabJack is fast enough for that measurement.

Next thing to do is to get an old DC motor and a thyristor drive. Hook it up for braking and breake away. In such an arrangement, the LabJack can do the job.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Cadbhoy]

Hi,

I'm in the UK, I should have said that, sorry.

re: the DC motor and a thyristor drive - I'm going to need to create a known load so I can chart torque speed curves and record things like starting torque.

Would this be easy to set up?

cheers
CB

 

[Skogsgurra]

Yes. If you don't need better than around five percent torque accuracy. Then you can use the DC motor's armature current to measure torque. If you need better accuracy, you can calibrate against known torque at standstill. That will give you reasonable accuracy at low speeds where friction and windage don't cause much trouble.

For best accuracy, you need a torque transducer.

The beauty with the DC drive is that you can set current limit to get constant torque. And it doesn't run hot - most of the energy is sent back to the grid.

For comparative measurements, a DC motor is perfect. Even without calibration or torque transducer. But you need to run the excitation with constant current.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...