How to evaluate a Servo motors parameters?

[kashif22041]

I have purchased a servo motor from a scrap dealer and it doesnt have any label of any sort.
It is from Buehler.

I need to know the parameters of the motor like
RPM
Torque
Gear ratio
and others.
I m using it in my final year project.

Can any one pls tell me a method to calculate or evaluate these parameters?:?::?::?:

Thanks in advance for ur help and time.

 

[svhb]

Better way : I need a servomotor with a certain torque, speed, ... and then I look for one that suit my needs ;-)

 

[jorgito]

Hello kashif22041,

Without a name plate, it would be a bit dificult to determine that motor parameters.
I assume that you have searched for a similar motor in the Bühler website, and not found your exact model. Rigth?
First, try to compare your motor with the ones in www.buehlermotor.com and try to determine the RPM rating of your specimen. If you find nothing similar, try 3000 RPM. After that apply enough voltage to bring the motor to that RPM value. Use a perforated disk in the motor axis and a freq. meter, for example, or an optical RPM meter if you have one. Now you can determine Kv. Kt is aproximately the same number as Kv (in the corrsponding coherent units, of course). It could be harder to determine the current rating, but you can manage to load your motor monitoring the case temperature. Increment load and current slowly until you have some 50 ºC above ambient.
For the gear ratio you'll need access to both ends of motor.

Good luck and best regards!

Edit: As Stefaan said, you may have a little encoder in your motor. It could be used to measure RPM. The gear ratio could also be determined disassembling the gear box, but be carefull on not disassembing the motor itself, or you can demagnetize it. Regards!

 

[svhb]

For the gear ratio you'll need access to both ends of motor.

For servomotors it is not uncommon to have a position feedback in the motor itself. So look for extra connections for accessing an encoder or resolver.


Stefaan