The operation characteristics are defined as the graphical dependencies of the speed n (or slip s), of the torque T, of the efficiency h, of the power factor cosj1, of the input current I1, of the input power P1, by the output power P2, all of them, determined in normal operation conditions:
- supplying voltage U1 = ct. = U1N ;
- frequency of the supplying voltage f1 = ct. = f1N ;
- additional resistance in the rotor R2s = 0 (for the wounded rotor asynchronous machines).
As example, in the figure below are plotted the named dependencies for a squirrel cage machine by 50 kW rated power.
The operation characteristics can be experimentally determined even by the direct loading of the machine (load applied within the limits 0 ÷ 1,2
· PN), or by a synthetic method. The first, even it implies a high energy consumption, is more precise.
