Power factor and three-phaseQuestion 1208 of 1506

Why can a large synchronous motor help a plant that has many induction motors?

It has a lagging power factor that adds to the lagging line current.
Its leading current offsets the lagging line current.
It raises the line frequency above 60 Hz and so lowers the current.
It has a unity power factor only while its shaft is not loaded.

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Correct answer: Its leading current offsets the lagging line current.

A leading current from the synchronous motor cancels part of the lagging current of induction loads.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 13.2: Synchronous Motors

Questions last reviewed: 18 October 2026

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