drop voltage at the time of a starting motor

[jeandemass]

I have to calculate a drop voltage with X'd and X''d when my motor start, but I do not know how to do?
Is there somneon who know what formulate I have to use?

 

[weh3]

You need to figure out the impedance of the transformer in ohms, and set up a voltage divider between the transformer and the motor. If you have a long cable run between the two, you need to include that, too. This will give you the voltage on starting the motor. It will be just like the resistive voltage dividers you did in EE 101, with inductors instead of resistors.

If anyone has an easier way to figure it, or a way to figure voltage dip when a backup generator is involved, I would be glad to hear.

Regards,
William

 

[jraef]

The formulais complex, and requires knowing a lot of information about not only the power source, but also the motor torque curves and the load accelerating torque requirements. There are several software programs that can do this for you, some more complete than others. SKM is one, there are several others mentioned in this forum. Use the Keyword Search to look at other threads on "large motor starting" or "voltage drop".

"Venditori de oleum-vipera non vigere excordis populi"