Will VFD improvement or lower the power factor
Will VFD improvement or lower the power factor
(OP)
Hi all, I'd like to know if a motor installed VFD would improve or lower the power factor, and why? Thanks!!
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Will VFD improvement or lower the power factor
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RE: Will VFD improvement or lower the power factor
RE: Will VFD improvement or lower the power factor
RE: Will VFD improvement or lower the power factor
The total power factor is calculated as the input watts divided by the input VA where the total RMS current including harmonic currents is used to calculate VA. The level of harmonics is determined by the source impedance at the drive input terminals. If the source impedance is low (available fault current is high), the harmonic current will be high and the power factor will be low. If the source impedance is high (available fault current low), the harmonic current will be low and the power factor will be high. The total power factor of a VFD might be lower than the power factor of a motor without a VFD.
Even if the total power factor of the VFD is lower than the power factor of a motor without a VFD, adding a VFD may not reduce the total power factor of the plant. The total power factor of the plant must be calculated as the plant watts divided by the total plant VA including harmonics currents. When harmonic current is included, the total current is the square root of the sum of the square of the fundamental current plus the square of the harmonic current.
RE: Will VFD improvement or lower the power factor
otherwise it is likely to be a worse power factor.
RE: Will VFD improvement or lower the power factor
RE: Will VFD improvement or lower the power factor
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Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: Will VFD improvement or lower the power factor
calculate harmonics.
The reason power companies dislike current flowing out
of phase with their voltage is because it takes capacity
from the system without generating sales of watts.
So any current flowing orthoganal to the the voltage
is a loss for the utilities be it harmonics or phase shift
due to inductive loads.
I worked at a location with a large spot welder that
consumed massive current for only 13 cycles of the
power line and then idle for 1 min. The power company
did not like this machine and charged extra for the
imbalenced load.