575/600 V VFD planning current calculator

Preliminary estimate

Inputs

Calculation note

Use this as a planning current screen only. Manufacturer VFD data and motor application details govern selection.

Method

Estimated input current = hp x amps per hp factor

Drive class is a planning label from entered horsepower range

Default factor = 1.27 A per hp

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Formula variables

  • hp is the motor horsepower used for the planning screen.
  • Amps per hp is an editable current factor.
  • Estimated input current is a preliminary comparison value.
  • Manufacturer VFD nameplate and application data govern final use.

Assumptions

  • The default factor is a conservative planning value for 575/600 V class drive comparisons.
  • Manufacturer VFD input-current data governs final selection.
  • Motor application, overload duty, bypass, enclosure, harmonics, and environmental conditions can change the selected drive.
  • This calculator does not select a drive, overload setting, bypass, conductor, breaker, fuse, or motor compatibility.

Examples

20 hp drive screen. A 20 hp motor at 1.27 A/hp estimates about 25.4 A preliminary VFD input current.

Large-drive workflow. For larger or engineered drives, replace the factor with manufacturer input-current data.