Thread Subject: Power Synchronous Motor

Hi there,

what is the best way to determine the Power (P electrical) of the synchronous machine in SimPowersystems. I have tried to solve it using the following formula:P= Isq^2 *3 * R.
However, the value is lower than my mechanical power although it should be higher.

Thanks for your help!

Dennis

"Dennis " <questions@gmx.eu> wrote in message <h99ij1$sc6$1@fred.mathworks.com>...
> Hi there,
>
> what is the best way to determine the Power (P electrical) of the synchronous machine in SimPowersystems. I have tried to solve it using the following formula:P= Isq^2 *3 * R.
> However, the value is lower than my mechanical power although it should be higher.
>
> Thanks for your help!
>
> Dennis

Hi,
the synchronous machines contain the electrical power output in its output vector 'm'. Attach a bus selector to this output port and in the dialog box of the selector you can select the active power output ('Output active power Peo').
I don't know which resistance the 'R' in your equation is. I hope it is not the value of the stator resistance because then you would get the losses of the machine which are actually quite small compared to the mechanica power input. If you had a 3-ph pure ohmic load attached to the machine the formula would give the electrical power - if the rotating speed has settled and remains constant. With only a resistive connected to the machine terminals the rotational speed remains constant if you input the stator losses plus the electrical load according to your equation as mechanical inpt to the machine.

Regards
F.W.