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When the rotor is blocked, due to the reduced supplying voltage (that is the voltage across the magnetising impedance if we consider the equivalent "p" circuit), the current that flows through the magnetising inductance can be approximated to be null (can be neglected) and

.

The line current, the line-to-line voltage (I_c, U_c) and the absorbed active power (P_c) are measured, when the rotor is blocked (Figure 7).

Figure 7

The active power P_c is consumed by the sum of the stator resistance R₁ and of the rotor resistance, reported to the stator R¢₂. It results

R¢₂ = 1,93 W.

Then is computed the sum of the stator impedance Z₁ and of the rotor impedance reported to the stator Z¢₂. It results

L_1s = L¢_2s = 0,02 H.

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