Electrical Load Calculator
A 15 kW three-phase load at 415V and 0.85 power factor draws 24.5 A and needs a 32 A MCB. Enter your power, voltage and phase configuration below to calculate current, kVA, kVAr, power factor correction capacitor size and MCB/fuse rating.
This tool computes full-load current, apparent power, reactive power, and recommends the next standard MCB/fuse rating for single-phase and three-phase electrical loads at common industrial voltages.
Electrical Load Inputs
Electrical Load Results
| Property | Value | Unit |
|---|
Electrical Formulas
Three-phase current:
Single-phase current:
Power triangle:
PF correction capacitor:
Frequently Asked Questions
How do I convert kW to amps for a three-phase supply?
For three-phase: I = P / (sqrt(3) x V x cos phi). For example, 15 kW at 415V and PF 0.85 gives 15000 / (1.732 x 415 x 0.85) = 24.5 A. This calculator does the conversion instantly for any voltage and power factor.
What is the difference between kW, kVA, and kVAr?
kW is real (useful) power, kVA is apparent (total) power, kVAr is reactive power. They form a power triangle: S (kVA) squared = P (kW) squared + Q (kVAr) squared. Power factor = kW / kVA. Low PF means you draw more current than needed for the same useful work.
What is power factor correction and why do I need it?
Power factor correction uses capacitors to cancel reactive power from inductive loads. Improving PF from 0.85 to 0.95 reduces apparent power by about 10%, meaning smaller cables, lower losses, and no utility penalty charges.
How do I select the right MCB or fuse rating?
Select the next standard MCB rating above the calculated full-load current. Standard ratings are 6, 10, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125, 160, and 200 A. The MCB must also match the number of poles and breaking capacity for your installation.
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Our engineers can design complete electrical systems for heat pump installations, including power supply, MCB sizing, and power factor correction.
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