high slip electric motors

if a high slip motor name tag says its 1100 rpm why does it run 1190 rpm on the test bench with no load

 

[umn]

One reason for this 10 rpm difference could be: the supply frequency is slightly less than the specified frequnecy.

 

[Pereirinha]

(I supose this is a induction motor)<br><br>In my opinion, probably this bigger speed at no load (1190 rpm) than at nominal/full load (1100 rpm), is due to the fact that with no load the &quot;resistant or load torque&quot; is smaller than the torque at nominal load. Then the &quot;equilibrium point&quot; between electromagnetic torque and resistant torque is attained for a bigger speed. It can be clairly seen if you observe a typical speed-torque curve: a smaller torque implies a bigger speed (i.e. it aproches to the synchronous speed).<br><br>Regards<br><br>Paulo Pereirinha