Unknown DC motor Specifications

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Discussion Overview

The discussion revolves around identifying the specifications of an unknown DC motor found in a college lab. Participants explore methods to test the motor's properties, including its speed, resistance, and performance under varying loads. The scope includes practical testing approaches and equipment recommendations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using a dynamometer to identify the motor's properties and asks for details about the engravings on the motor to confirm its type.
  • Another participant confirms it is a DC motor and plans to provide the engraved details later, while also checking for a dynamometer in the machine shop.
  • A different participant recommends using a tachometer to measure the motor's RPM and a multimeter to find the rotor resistance, stating that these measurements can lead to further calculations.
  • Another suggestion is to apply a varying load to the motor's shaft while measuring current and voltage to create a complete motor curve, emphasizing the importance of a dynamometer for this process.

Areas of Agreement / Disagreement

Participants generally agree on the need for specific testing equipment and methods to determine the motor's specifications, but there are multiple approaches suggested, and no consensus on a single method is reached.

Contextual Notes

Limitations include the lack of initial specifications for the motor, dependence on the availability of testing equipment like a dynamometer and tachometer, and the need for further details about the motor's engravings.

teknodude
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Me and another person were rummaging through one of my colleges labs looking for usable parts for my groups product design course. We found this medium size motor that weighed about 2-3 pounds. The problem is that there were no stickers at all that indicated its specifications. There were a few numerical engravings, but without words it was hopeless. We hooked it up to a 12 V power source and it powered up fine. Does anyone know of an easy apparatus we can set up to test for its specifications? Maybe hook it up to an arm and having the arm depress a scale?
 
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teknodude said:
Me and another person were rummaging through one of my colleges labs looking for usable parts for my groups product design course. We found this medium size motor that weighed about 2-3 pounds. The problem is that there were no stickers at all that indicated its specifications. There were a few numerical engravings, but without words it was hopeless. We hooked it up to a 12 V power source and it powered up fine. Does anyone know of an easy apparatus we can set up to test for its specifications? Maybe hook it up to an arm and having the arm depress a scale?

A dynamometer will help identify some of it's properties.

http://en.wikipedia.org/wiki/Dynamometer

What was engraved on the motor? Is it DC or AC?

CS
 
It's a DC motor. I'll post what was engraved on the motor on monday. I put the motor in my schools machine shop for storage, and they're not open on the weekend... Also I'll check if they have a dynometer that I can check out.
 
just find some tachometer, find its rpm.
get a multimeter, find its rotor resistance.
everything can be pretty much calculated from these two
 
The best way is to be able to apply a varying load on the shaft and then measure the current and voltage. That way you can vary the speed and get a calculation on power at various speeds. That will give you a complete motor curve that you can then use for whatever application you want. A dyno is exactly what this is for. You can try to improvise the loading mechanism though.
 

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