Salient Pole Synchronous Motor

The analysis of salient pole synchronous motor is based on the Blondel’s two reaction. The direct and quadrature axis components of current and reactance are same as defined earlier for the synchronous generators. Thus,

X_d = Direct axis reactance
X_q  = Quadrature axis reactance
I_d  = Direct axis component of I_a
I_q = Quadrature axis component of I_a

The complete phasor diagram of lagging p.f. is shown in the Fig. 1.

Fig. 1 Phasor diagram for lagging p.f.

From the phasor diagram it can be derived that,

Note : For the proof of above results refer example 2.

The complete phasor diagram of leading p.f. is shown in the Fig. 2.

Fig. 2  Phasor diagram for leading p.f.

For this leading p.f. case,

Note : ? should be taken negative for the leading power factor for calculating other parameters.
While the mechanical power developed per phase is given by,

Total P_m  = 3 x P_m  

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