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Three Phase Power Calculator - Calculate Power, Current & Voltage
Calculate three-phase electrical power, current, and voltage with support for balanced and unbalanced loads. Free 3-phase power calculator with delta and wye configurations, power factor calculations, and electrical formulas.
System Configuration
Wye (Star) Configuration: Line voltage = √3 × Phase voltage. Common in distribution systems with neutral.
Electrical Parameters
Motor Efficiency (Optional)
Common System Voltages
Calculation Results
Line Voltage
480 V
Line Current
10 A
Phase Voltage
277.13 V
Phase Current
10 A
Power Analysis
Formulas Used
Three-Phase Power:
P = √3 × VL × IL × cos(φ)
Apparent Power:
S = √3 × VL × IL
Wye Relationships:
VL = √3 × VP
IL = IP
3-phase power calculator parameters
- Voltage (V): Enter the phase-to-phase () voltage for a 3-phase AC supply in volts.
- Current (I): Enter the current in Amperes (A).
- Power factor (cos φ): Enter the power factor of the load. It is between 0 and 1.
How to calculate 3-phase power?
The 3-phase power formula for active power is:
Where,
- • is the 3-phase line voltage,
- • is the current, and
- • is the power factor between 0 and 1.
The 3-phase power formula for apparent power is:
Where,
- • is the 3-phase line voltage, and
- • is the current.
The 3-phase power formula for reactive power is:
Where,
- • , and
- • is the power factor between 0 and 1.
An alternative 3-phase power formula for reactive power is:
Where,
- • is the 3-phase apparent power, and
- • is the 3-phase active power.
⚠️ Electrical Safety Warning
Before Working with Three-Phase Systems
- • Always turn off power and verify with meters
- • Follow lockout/tagout procedures
- • Use appropriate PPE (arc flash protection)
- • Verify phase sequence before connecting motors
- • Have qualified electricians perform installations
Three-Phase Hazards
- • High voltages (208V-600V+) can be lethal
- • High fault currents can cause arc flash
- • Motors can start unexpectedly
- • Neutral loss in Wye systems creates hazards
- • Wrong phase rotation can damage equipment
Frequently Asked Questions
What is three-phase power and how is it calculated?
Three-phase power is electrical power transmitted using three alternating current waveforms, each 120° out of phase. For balanced loads: P = √3 × VL × IL × cos(φ), where VL is line voltage, IL is line current, and cos(φ) is the power factor. This provides more efficient power transmission than single-phase systems.
What's the difference between Delta and Wye (Star) configurations?
In Delta configuration, loads are connected in a triangle with line voltage equal to phase voltage (VL = VP). In Wye (Star) configuration, loads connect to a common neutral point with line voltage = √3 × phase voltage (VL = √3 × VP). Wye provides a neutral point and is common in distribution systems.
How do I calculate three-phase motor current?
For a three-phase motor: I = P / (√3 × V × cos(φ) × η), where P is motor power (watts), V is line voltage, cos(φ) is power factor (typically 0.8-0.9 for motors), and η is motor efficiency (typically 85-95%). This gives you the line current needed for proper wire sizing.
What is power factor and why is it important?
Power factor (cos φ) is the ratio of real power to apparent power, ranging from 0 to 1. It indicates how efficiently electrical power is used. Low power factor (below 0.85) results in higher current draw, increased losses, and utility penalties. Motors, transformers, and fluorescent lights typically have lagging power factors.
How do balanced and unbalanced loads affect calculations?
Balanced loads have equal impedance on all three phases, allowing simpler calculations using standard formulas. Unbalanced loads require individual phase calculations and can cause neutral current in Wye systems. Unbalanced systems are less efficient and can cause equipment problems.
What safety considerations apply to three-phase electrical work?
Three-phase systems involve high voltages and currents that can be lethal. Always: turn off power and verify with meters, follow lockout/tagout procedures, use proper PPE, ensure proper grounding, verify phase sequence for motors, and have qualified electricians perform installations. Never work on live three-phase equipment without proper training.
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