Power-factor relationship
Relationship chart for kW, kVA, kVAr, power factor and power-factor-correction estimates.
Power, apparent power and correction relationships
Use these row summaries to read the calculation relationship before checking the value table.
Power factor
Read PF from real and apparent power values.
PF = kW / kVAReal power
Convert apparent power to real power.
kW = kVA x PFApparent power
Estimate kVA from real power.
kVA = kW / PFReactive power
Show reactive component from kW and kVA.
kVAr = sqrt(kVA^2 - kW^2)Angle relationship
Prepare tan(phi) for correction estimates.
phi = arccos(PF)Correction estimate
Estimate capacitor kVAr from existing and target PF.
kVAr = kW x (tan(phi1) - tan(phi2))
- Real, apparent and reactive power relationships used by released calculators.
- Show kW, kVA, kVAr and power-factor relationships without selecting correction equipment.
- Engineering formula context; utility and equipment requirements govern correction decisions.
- PF = kW / kVA, phi = arccos(PF), and tan(phi) relationships use values from the same load record.
- Power-factor correction estimates depend on existing PF, target PF and lagging or leading context; equipment and utility review still controls selection.
Power-factor formulas used for load records
Show kW, kVA, kVAr and power-factor relationships without selecting correction equipment.
| Relationship | Formula | Use | Boundary |
|---|---|---|---|
| Power factor | PF = kW / kVA | Read PF from real and apparent power values. | kW and kVA must belong to the same project load record. |
| Real power | kW = kVA x PF | Convert apparent power to real power. | PF must be entered as a decimal from the project record. |
| Apparent power | kVA = kW / PF | Estimate kVA from real power. | PF close to zero is not a valid project planning input. |
| Reactive power | kVAr = sqrt(kVA^2 - kW^2) | Show reactive component from kW and kVA. | Not equipment selection by itself. |
| Angle relationship | phi = arccos(PF) | Prepare tan(phi) for correction estimates. | Record lagging or leading project context before using a correction relationship. |
| Correction estimate | kVAr = kW x (tan(phi1) - tan(phi2)) | Estimate capacitor kVAr from existing and target PF. | Manufacturer and utility review still controls selection. |
- Use calculators for entered values and result warnings.
- This chart does not choose capacitors or switchgear.
Formula variables
Use these symbols and units when reading the chart rows.
| Variable | Meaning | Unit | Use |
|---|---|---|---|
| kW | Real power. | kW | |
| kVA | Apparent power. | kVA | |
| PF | Power factor as a decimal. | PF = kW / kVA for the same load record. | |
| phi | Power-factor angle. | rad or deg | phi = arccos(PF). |
| tan(phi) | Reactive-power tangent relationship. | Used when estimating kVAr correction. | |
| phi1 | Existing power-factor angle. | Derived from the existing PF entered by the user. | |
| phi2 | Target power-factor angle. | Derived from the target PF entered by the user. | |
| kVAr | Reactive power. | kVAr | Correction estimates still need equipment and utility review. |
| PF_existing | Existing lagging or leading power factor. | Leading/lagging context must be recorded before correction planning. | |
| PF_target | Target power factor. | Do not treat the target as a utility approval or product setting. |
Worked relationship example
This example shows how one set of entered values reads through the relationship.
kW, kVA and correction relationship reading
An 80 kW load is reviewed from an existing lagging PF of 0.78 toward a target PF of 0.95.
- Real power
- 80 kW
- Existing PF
- 0.78 lagging
- Target PF
- 0.95
- Find kVAkVA = kW / PF = 80 / 0.78 = 102.6 kVA.
- Use angle relationshipkVAr estimate = kW x (tan phi1 - tan phi2), where phi = arccos(PF).
- Estimate correctionUsing the entered PF values gives about 38 kVAr before equipment and utility review.
This is a relationship example only; capacitor staging, switching and harmonic context need separate review.
Use the result as a power-factor relationship review estimate, not a capacitor selection or network approval.
- Existing and target PF values describe the same load record.
- Lagging or leading context is recorded before correction planning.
Where the power-factor chart belongs
Use the chart to understand the formula basis; calculators handle project-specific inputs, warnings and results.
| Item | Value |
|---|---|
| Purpose | Show kW, kVA, kVAr and power-factor relationships without selecting correction equipment. |
| How to use the source | Real, apparent and reactive power relationships used by released calculators. |
| Standards and project context | Engineering formula context; utility and equipment requirements govern correction decisions. |
| Where judgement is still needed | Use this chart to understand the relationship behind a calculation; do not treat it as a substitute for entered project values. |
| Before relying on it | Confirm current standards, local authority requirements, DNSP conditions, project documents and manufacturer data before relying on a decision. |
| Context | Applies to | Public boundary |
|---|---|---|
| Engineering power relationships | kW, kVA, kVAr, PF, phi and tan(phi) relationships | The chart does not select capacitor banks, switchgear, control stages or utility-approved settings. |
| Utility and equipment review | Existing PF, target PF and lagging or leading context | Use the result as an estimate before checking tariff, equipment, harmonic and manufacturer requirements. |
| Project review boundary | Power-factor relationship chart | Confirm current Australian standards, local authority requirements, DNSP conditions, project documents and manufacturer data before relying on a decision. |
Formula basis for power-factor relationships
Review the cited calculator formulas, utility/equipment boundary and checked date before using these relationships in a correction worksheet.
| Item | Value |
|---|---|
| Source | AUWiring kVA/kW/PF and power-factor-correction calculator formulas. |
| Source type | Released calculator formula source |
| Derivation basis | Derived from general electrical power relationships and AUWiring calculator logic. |
| Last checked | 2026-07-13 |
| Review interval | Annual or when calculator formulas or power-factor wording changes. |
| Review trigger | Calculator formula change, equipment-context change or project feedback. |
| Version used | R10-2026-07-13 |
| Australian application | Australia; equipment, utility and project requirements can override general estimates. |
Use a calculator for project values
Use the chart to read the formula relationship, then open a calculator when you need entered project values, warnings and result context.