Turning now to the influence of the d.c. excitation current, at a given supplyfrequency (i.e. speed) the utility-frequency e.m.f. (E) induced in the stator isproportional to the d.c. field current fed into the rotor. If we wanted to measure thise.m.f. we could disconnect the stator windings from the supply, drive the rotor atsynchronous speed by an external means, and measure the voltage at the statorterminals, performing the so-called open-circuit test.
đang được dịch, vui lòng đợi..
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