Three-phase power matrix calculator
Calculate Australian three-phase kVA, kW, kVAr and current cross-check values from entered voltage, current and power factor.
S = sqrt(3) x V_LL x I / 1000; P = S x PF; Q = S x sin(arccos(PF)); I_check = P x 1000 / (sqrt(3) x V_LL x PF)- Voltage is entered as line-to-line voltage.
- Current is entered as balanced line current.
- PF must be above 0 and not greater than 1.
- The calculator does not assess voltage unbalance, current unbalance, harmonic content or metering uncertainty.
| Variable | Meaning | Unit | Use |
|---|---|---|---|
| S | Apparent power | kVA | Three-phase apparent power from line voltage and current. |
| V_LL | Line voltage | V | Entered line-to-line voltage. |
| I | Line current | A | Entered balanced three-phase line current. |
| PF | Power factor | ratio | Entered power factor for the operating point. |
| P | Real power | kW | Apparent power multiplied by PF. |
| Q | Reactive power | kVAr | Reactive component from the power triangle. |
| I_check | Current cross-check | A | Current recalculated from kW, voltage and PF. |
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Three-phase power matrix calculator technical guide
Calculate Australian three-phase kVA, kW, kVAr and current cross-check values from entered voltage, current and power factor.
Use this calculator when a three-phase load needs one visible relationship record: line voltage, line current, power factor, apparent power, real power and reactive power. It is useful for Australian switchboard notes, plant load records, estimating checks and handoffs into demand, cable or power-factor workflows.
The calculator is intentionally narrow. It assumes the entered values represent a balanced three-phase operating point and does not check voltage unbalance, current unbalance, harmonic distortion, instrument uncertainty, protection settings or equipment suitability.
Power Matrix Use Cases
| Work situation | Entered basis | Useful output | Outside the result |
|---|---|---|---|
| Switchboard load note | Line voltage, line current and PF | kVA, kW, kVAr and current cross-check | Cable size or protection decision |
| Plant estimate | Nominal 400 V, current and expected PF | Power matrix for an estimating record | Metering confirmation or load balance proof |
| Metering summary | Measured current and measured PF | Consistent relationship values | Instrument accuracy or data logging analysis |
| Demand handoff | kW and kVA context from current | Values for demand or tariff worksheets | Tariff interpretation |
| Correction planning | Reactive component visible beside real power | kVAr context before correction worksheet | Capacitor equipment selection |
A matrix record is strongest when the voltage, current and PF are all from the same operating condition. Mixing a design current with a measured PF from another period can make the relationship look more precise than it is.
Three-Phase Boundary
| Included in this calculator | Not included in this calculator |
|---|---|
| Line-to-line voltage | Phase-by-phase voltage unbalance |
| Balanced line current | Current unbalance or neutral current |
| Entered PF | Harmonic distortion or waveform quality |
| kVA, kW, kVAr and PF angle | Cable, protection or transformer selection |
| Current cross-check | Meter calibration or instrument uncertainty |
The boundary matters because the formula is only a relationship between entered values. A real installation may need separate measurement, balancing, protection, harmonic or manufacturer checks before design decisions are made.
Input Checklist
| Input | Strong basis | Weak basis |
|---|---|---|
| Matrix reference | Switchboard, meter, load or estimate record | Generic note with no traceable load |
| Line voltage | Measured or documented line-to-line value | Assumed value that does not match the site |
| Line current | Balanced current basis for the same load condition | One phase current used as if all phases match |
| Power factor | Measured, calculated or documented PF for the same period | PF copied from a different load or tariff note |
| Review context | Project note naming how the matrix will be used next | Output copied into another worksheet with no source |
If each phase has materially different current or voltage, keep a separate load-balancing or unbalance record instead of reducing the condition to one balanced matrix.
Review Workflow
- Name the switchboard, load, meter or estimate being represented.
- Confirm the line-to-line voltage basis for the Australian project context.
- Enter the balanced line current value for the same operating condition.
- Enter the power factor value that belongs with that current and voltage.
- Read kVA, kW, kVAr, PF angle and current cross-check together.
- If PF is very low, check the metering basis and load condition before relying on the reactive result.
- Send the output to the next calculator only when the source values and assumptions are recorded.
- Use separate records for unbalance, harmonics, cable sizing, protection, correction equipment or tariff interpretation.
The workflow makes the three-phase relationship visible without pretending the matrix is a full electrical design review.
Worked Australian Examples
| Situation | Entered values | Output reading | Practical note |
|---|---|---|---|
| 400 V plant load | 400 V, 180 A, PF 0.86 | 124.71 kVA, 107.25 kW and 63.64 kVAr | Keep the load condition with the result. |
| Planning record | 400 V, 95 A, PF 0.90 | Compact matrix for an early estimate | Nominal voltage is a worksheet basis only. |
| Low PF matrix review | 400 V, 140 A, PF 0.64 | Matrix is calculated with a PF review note | Check metering before using the reactive value. |
These examples use common Australian three-phase context, but the entered voltage should always match the actual project record.
Related Tools
Use the kVA, kW and power factor calculator when the task is a smaller two-value conversion. Use the reactive power kVAr calculator when the kVAr side of the power triangle needs its own record. Use the power-factor relationship chart when the task is explanation rather than calculation.
| Next question | Use next |
|---|---|
| Convert kVA, kW and PF without current | kVA, kW and power factor calculator |
| Derive kVAr from kW and PF or kW and kVA | Reactive power kVAr calculator |
| Explain the power triangle | Power-factor relationship chart |
| Review low PF correction need | Power factor correction calculator |
Stop Points
- The load is materially unbalanced across phases.
- Voltage values are phase-to-neutral while the calculator expects line-to-line voltage.
- Current and PF come from different operating conditions.
- Harmonics or waveform distortion are material to the decision.
- The matrix is being used as a cable, protection or equipment selection result.
Export the matrix only with the voltage, current, PF source and intended next use. The result is a relationship record, not a complete design decision.
400 V three-phase load matrix
A switchboard note converts a measured three-phase current into kVA, kW and kVAr values.
- Reference
- TPM-1
- Line voltage
- 400 V
- Current
- 180 A
- Power factor
- 0.86
- Apparent power124.71 kVA
- Real power107.25 kW
- Reactive power63.64 kVAr
124.71 kVA and 63.64 kVAr.
The matrix keeps apparent, real and reactive power together so downstream power-factor and tariff checks use the same basis.
- Line voltage is entered as the three-phase line-to-line voltage.
- The current is the balanced three-phase line current.
- The power factor is entered by the user.
Nominal Australian supply context
A planning record uses a 400 V three-phase nominal input for a balanced plant load.
- Reference
- TPM-2
- Line voltage
- 400 V
- Current
- 95 A
- Power factor
- 0.9
- Apparent power65.82 kVA
- Real power59.24 kW
- Reactive power28.69 kVAr
65.82 kVA and 28.69 kVAr.
The result gives a compact power triangle record before cable, demand or equipment worksheets are used.
- The voltage value is a nominal worksheet input.
- The load is treated as balanced for this calculation.
- Measured unbalance and harmonics need separate records.
Low PF matrix review
A plant estimate uses a low power factor to decide whether more metering context is needed.
- Reference
- TPM-3
- Line voltage
- 400 V
- Current
- 140 A
- Power factor
- 0.64
- Apparent power96.99 kVA
- Real power62.08 kW
- Reactive power74.53 kVAr
96.99 kVA and 74.53 kVAr.
The matrix can be calculated, but low power factor should be checked before relying on the reactive component.
- The entered PF reflects the operating condition being reviewed.
- The calculator does not size correction equipment.
- Reactive power records should be paired with metering context.