Measuring Inductance.. How?

[Faizan Jawaid]

measuring inductance

If somebody could let me know how to calculate Inductance of a stepping motor coil. I have an old stepper motor with nameplate torn. So i need to know how to calculate inductance of one of its coils.

Regards.

 

[sunderwood]

how to calculate inductance of stepper motor

You can do two tests to electrically characterize your stator. You'll need some sort of current sensor and scope (there might be ways around that).
First, apply a DC voltage (less than rated voltage) to one (or two, if neutral isn't accessible) phase, and measure the final current, this will give you the resistance.
Then, connect your scope to the current sensor and measure the transient response of the circuit.
If t=0 is the time at which you apply the voltage, then, if i remember right, the time at which you reach two thirds of the final value is equal to L/R. Since you know R, you can find L.
Also keep in mind if you used 2 phases you'll need to divide your results by two.
One last thing: in stepper motors the stator inductance can be heavily affected by the rotor position. Depending on how much time you have, keep track of your rotor position and measure L for a few points of a complete electrical revolution.
Good luck !

 

[Faizan Jawaid]

Thanks alot...I try measuring L using scope....