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A voltage boost is applied at low frequency in a V/f drive to compensate for

  • A.the increase in the iron loss of the machine at low frequency
  • B.the reduction in the rotor resistance at low frequency
  • C.the increase in windage loss at reduced speed
  • D.the stator resistance drop

Answer: D

At a few hertz the resistive drop is a large fraction of the applied voltage, so the flux would collapse without an addition. The boost is either a fixed offset or is computed from the current, which is the more accurate arrangement.

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