kW, kVA and power factor workflow

How to move between real power, apparent power and power factor before using Australian current, demand or correction calculators.

Relationship purpose

kW records real power. kVA records apparent power. Power factor connects the two values for a.c. loads. When a load record mixes those terms without context, downstream current, demand and correction estimates become hard to trust.

The useful task is naming which value is known, which value is being solved and whether the source is strong enough for the next calculation.

Workflow

  1. Identify the known value: kW, kVA or power factor.
  2. Confirm whether the value is from a nameplate, schedule, meter, design estimate or invoice context.
  3. Use the kVA/kW/PF calculator to solve only the missing relationship value.
  4. Carry the result into current, demand or correction review with the input source attached.

Relationship table

kW, kVA and power-factor decisions
TaskInputs to prepareUseful outputDo not infer
Find kVA from kWkW and PFApparent power estimateEquipment size or network approval
Find kW from kVAkVA and PFReal power estimateActual demand without load context
Find PFkW and kVARatio for reviewCorrection equipment setting
Estimate currentPower value, phase, voltage and PF where neededCurrent estimateCable suitability

Boundaries

  • Do not use kW as kVA without checking power factor.
  • Do not turn a relationship result into equipment selection.
  • Do not mix measured and scheduled values without labelling them.
  • Do not move the result into a project record unless the input source is named.

Questions

Can kW and kVA be treated as the same value?

Only when power factor is 1.0. Most a.c. load records need the power-factor basis kept with the power value.

Which value should be used for current?

Use the documented value. If apparent power is known, use kVA. If real power is known, keep the power factor with the calculation.