Power factor of motor with VSD?

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SUMMARY

The discussion centers on the power factor (PF) of a motor equipped with a Variable Speed Drive (VSD). A motor with a full load PF of 0.8 and a starting PF of 0.3 will maintain its starting PF at 0.3, regardless of the VSD's datasheet PF of 0.95. The VSD's power input is regulated to 0.95 through a PF correction circuit, but the motor's PF remains unchanged. The VSD must be appropriately rated to manage the reactive VAR of the motor load.

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TL;DR
Power factor at the motor with VSD
If I have a motor with a full load power factor of 0.8 and starting power factor of 0.3 and I install a VSD to run it with a datasheet power factor of 0.95, will the power factor during starting be 0.3 or 0.95? And at full load?

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Welcome to PF.

The power input to the VSD should be maintained at 0.95 by a PF correction circuit that controls the switching input rectifier.

The DC reservoir capacitors isolate the PF of the motor load, from the PF of the main supply.

The motor PF will not change, but the VSD must be rated to handle the reactive VAR of the motor load.
 
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