With normal full-field excitation of a synchronous motor, the power factor has a peak value of unity, or 100%, and the AC stator current is at its highest value.

Question

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With normal full-field excitation of a synchronous motor, the power factor can reach unity, but this condition corresponds to the most efficient operation, not to the highest AC stator current. The highest stator current occurs under conditions of under-excitation (leading to a lagging power factor) or over-excitation (leading to a leading power factor), not at unity power factor.

With Normal Full-Field Excitation of a Synchronous Motor, the Power