Load Testing Electric Motor

[vctech]

Hello,

I need to simulate a load on a small 2Hp electric motor we are using. Does anyone have any suggestions from previous experience? Are there any companies that make test equipment for this?

I had several ideas...
1) Drive a generator and applying a known electrical load to it.
2) Using a small brake assembly
3) Using a pulley system and attaching it to an indoor bicycle trainer device.

 

[drawoh]

vctech,

A brake can be extremely crude. Attach a disc to your shaft. Drape a belt over the disc. Fix one end of the belt. Hang a weight on the other end. You can work out the torque by experiment.

JHG

 

[Clyde38]

Try an internet search for dynamometers. Magtrol and Vibrac are two companies that I have had personal experience with. They are not cheap.

http://www.magtrol.com/index.html

http://vibrac.com/

Less expensive solution is a prony brake. Google for more.

http://www.buckleyoldengineshow.org/Spotlight/Horsepower-Testing-Pony-Brake

http://chestofbooks.com/crafts/popu...-Do/Prony-Brake-for-Testing-Small-Motors.html

[link

http://www.linkedin.com/in/clydehancock

]

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[Tmoose]

How long do you need the loaded test to run? Do you need to develop the full 2 HP?

 

[vctech]

5 minute intervals max. We are trying to do a fast and easy root cause analysis on a vibration in our system at rpm's above 1000 under known loads. We are trying to test the motor mount, and motor to eliminate them as the cause. I wanted to see if anyone had any experience or knew of any test equipment available.

 

[PeterCharles]

The last time I needed to do something like this I set up a simple drum with a belt wrapped round 180 degrees and a spring balance on each end of the belt. A simple calculation with torque and speed gives power.

 

[Tmoose]

First I'd get some detailed vibration measurements with frequency and magnitude information of a real system when it is running well, and also when the vibration is excessive. The frequency info would very likely point to source of the vibration. I'd use the actual load because I'd be worried that there is some interaction between the load and the base. For instance, if the driven device is belt driven at 1.7 X motor speed, sheave eccentricity, or shaft runout would create a nice tug at 1.7X motor speed. If the motor/base system as mounted has a natural frequency around 1800 cpm, then when the motor reaches a little over 1000 rpm, the motor will start hopping at 1800 cpm. If a test load is used driven at 1-1, then the 1800 cpm resonance may not get excited, and the motor base system will get an undeserved alibi.

 

[electricpete]

Good advice by Tmoose.

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