3-Phase Motor Calculator | Instant kW & HP Results
The essential tool for calculating 3-phase motor power. Get instant results for three common scenarios.
Interactive Power Calculator
The Core Formula, Demystified
This is the fundamental equation for calculating electrical input power. Click on any component to see its meaning.
Click a component above
Select any part of the formula to see what it represents.
Core Concepts Deep Dive
A brief overview of the key parameters that determine a motor's power consumption and output.
⚡ Voltage (V)
The electrical "pressure" in a circuit. For 3-phase motors, we use Line-to-Line Voltage ($V_{LL}$), the potential between two power conductors.
🌊 Current (I)
The "flow rate" of electricity. We measure Line Current ($I_L$), the amount of current flowing through a single power conductor.
🍺 Power Factor (cos φ)
A measure of efficiency, from 0 to 1. It's the ratio of working power (kW) to total power (kVA). A lower value means more wasted energy.
⚙️ Efficiency (η)
The motor's ability to convert electrical energy into mechanical work. It's never 100% due to heat and friction losses.
Frequently Asked Questions
Quick answers to common questions about 3-phase motors and power calculations.
What's the difference between line voltage and phase voltage?
Line voltage (VLL) is measured between two power lines. Phase voltage (VLN) is measured from one line to the neutral point. In a star (Y) system, VLL = √3 × VLN. Our calculator uses the more common Line Voltage.
What is a typical power factor for a 3-phase motor?
A fully loaded motor typically has a power factor of 0.85 to 0.90. This value drops significantly at lower loads, leading to less efficient power use.
Can I use this formula for a single-phase motor?
No. This formula, with its √3 constant, is exclusively for balanced three-phase systems. The formula for single-phase power is simpler: P = V × I × cos φ.
What happens if my three phases are unbalanced?
An unbalanced system can cause motor overheating and premature failure. The standard formula becomes inaccurate, and a proper analysis requires measuring the power of each phase individually.
Why is motor efficiency never 100%?
Energy is always lost during conversion. In a motor, electrical energy is lost as heat in the windings (copper losses), from magnetic effects (iron losses), and through mechanical friction.
What's the difference between kW and kVA?
kW (kilowatts) is Real Power, the energy that does useful work. kVA (kilovolt-amperes) is Apparent Power, the total power supplied. The relationship is: kW = kVA × Power Factor.
How does star (Y) vs. delta (Δ) connection affect the power calculation?
It doesn't! The formula P = √3 × VL × IL × cos φ works for both configurations when using Line voltage and Line current, which is a key reason for its universal use.