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I Need Help In Understanding Electric Motor Dynamometer Testing AC and DC Answered

OK extremely long time reader but first time poster. I need some help understanding dynamometer for electric motors. I would like to test motors under load up to 5HP. I have several motors and I would like to use a selected motor as the generator load. I understand this is a very broad question but I have to start somewhere.  

What are some things I might need?

Here are some things I have.
Motor speed controller 
Motor torque controller
Electric motors off all sizes 1/3 to 20HP
Some have a brake installed.

Would I need to use a motor with a brake and apply the brake as the load?

I don't want to use water or any fluids as a braking system. Also regenerative would be great also.

I thank you for the help.

5 Replies

d-stan1987 (author)2016-12-22

Thanks. I would like to test HP , Torque, and Amps. You said I would need a calibrated motor. Can you show me a link to a large HP calibrated motor? Just so we are on the same page.

So I would have two motors coupled together. Motor being tested (motor 1) and another large motor (motor 2).

When you say dead load. Does that mean no power is going to motor 2?

Beefy Larger DC motor for stalling motor 1. Can you please explain. Do you mean apply power to motor 2 so it fights against motor one. And I would keep increasing the power until motor 1 stops???? Tha is for the help.

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d-stan1987 (author)2016-12-21

thank you and sorry I didn't see your response. A matter of fact I have trouble even trying to find my own posts. I have used this site for many years just never posted before. Is there an area where I can see my own posts? I just bookmarked this page now so I can find it easily.

Anyways tha k you for the help. I want to test electric motors AC and DC up to 5 hp. I want to test the motor under a load. Just like a dynamometer would. I am not new to making things or testing motors and tons of other electronic equipment. Bit this one is just throwing me for a loop.

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Downunder35m (author)d-stan19872016-12-21

Ok, makes more sense now :)
I have only serviced something quite similar and maybe that's of help to you.
Apart from the fact that is was to test wind generators it went like this:
One motor (for me it was the generator - for you the one you want to test) drives another one with a "dead" load.
The dead load in my case was a DC motor with a fixed wire resistor over the terminals to check the available power with an inductive load at a given wind speed.
As you want to get some actual data in return you would need a calibrated motor for the testing - they are expensive.
Of course you can just take a really beefy DC motor and increase it's load until the driving motor stalls and record the output voltage and current.
Another way might be a magnetic brake, similar like those on modern exercise bikes.
Here something spins in a magnetic oil (usually minereal oil with very fine, black iron oxide) with an external magnetic field the viscosity of the oil is changed to the point of the motor stalling.
The voltage and amps required on the coil that modifies the magnetic field for the brake is the value to translate.
All depends if you just needs figures showing relative data or if you need actual torque/hp readings for the motor in question.

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Downunder35m (author)2016-12-18

Motors with a brake are for fast stopping or the slow and controlled release of a load.
Quite common on certain industrial machines as a protection for the operator, same as a good angle grinder that stops within 2 seconds after shutting off.
I am not sure what you actually want to test and without that any suggestions are pretty much useless ;)

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