If the rotor is kept blocked and if we grow the stator voltage, starting from zero (Figure 8), until

,

we are measuring

• the line-to-line voltage U_c,
• the line current I_c,
• the active power P_c.

Figure 8

In this case, the phase equivalent diagram (Figure 9) highlights the leakage inductances of the stator and of the rotor.

Figure 9

Due to the small voltage drop across the magnetising impedance, the magnetising current can be neglected. It results

and .

In these conditions, we obtain:

, respectively .

Also

.

If we assume the leakage inductances to be equal (L_1s = L¢_2s), it results

.

Taking into account the magnetising inductance, it results the total stator inductance and rotor inductance reported to the stator

,

.