Amps to VA Calculator
Amps to Volt-Amps (VA) Calculation Formulas
Single Phase Calculation
The apparent power S in volt-amps is equal to the current I in amps multiplied by the voltage V in volts:
Where:
- S(VA): Apparent power in Volt-Amps (VA)
- I(A): Current in Amperes (A)
- V(V): Voltage in Volts (V)
This formula is commonly used in electrical engineering to determine the apparent power flowing through a circuit when the current and voltage are known.
Three Phase Calculation
Calculation with Line to Line Voltage
The apparent power S in volt-amps (with balanced loads) is equal to the phase current I in amps multiplied by the square root of 3 times the line to line RMS voltage VL-L in volts:
Where:
- S(VA): Apparent power in Volt-Amps (VA)
- I(A): Current in Amperes (A)
- VL-L(V): Line to line voltage in Volts (V)
This formula is used for three-phase systems where the voltage is measured between two phases. It is essential for calculating the apparent power in industrial applications where three-phase power is common.
Calculation with Line to Neutral Voltage
The apparent power S in volt-amps (with balanced loads) is equal to the phase current I in amps multiplied by 3 times the line to neutral RMS voltage VL-N in volts:
Where:
- S(VA): Apparent power in Volt-Amps (VA)
- I(A): Current in Amperes (A)
- VL-N(V): Line to neutral voltage in Volts (V)
This formula is particularly useful in systems where the voltage is measured from a phase to the neutral point, such as in residential electrical systems.
Practical Example
For instance, if you have a single-phase system with a current of 10 A and a voltage of 230 V, the apparent power can be calculated as follows:
S(VA) = 10 A × 230 V = 2300 VA
This means that the apparent power flowing through the circuit is approximately 2300 Volt-Amps.
FAQs
Amperes (Amps) measure current flow, while Volt-Amperes (VA) measure apparent power in an electrical system. The relationship depends on the system voltage.
💡 Important: VA calculations differ for single-phase and three-phase systems.
For single-phase systems:
For three-phase systems:
Example for single-phase 230V circuit drawing 10A:
🔍 Note: For three-phase systems, use line-to-line voltage and line current.
Common equipment examples:
- Home Computer (230V single-phase, 2A):VA = 2A × 230V = 460 VA
- Industrial Motor (400V three-phase, 15A):VA = 15A × 400V × 1.732 = 10,392 VA
- Office Printer (230V single-phase, 5A):VA = 5A × 230V = 1150 VA
Key factors to consider:
- Voltage stability and fluctuations
- Power factor of the equipment
- Starting current vs. running current
- Single-phase vs. three-phase requirements
- Equipment efficiency ratings
📝 Tip: Always verify the voltage rating and phase configuration of your equipment.
Quick reference values for common systems:
- 230V Single-phase Systems:
- 1A = 230 VA
- 5A = 1150 VA
- 10A = 2300 VA
- 400V Three-phase Systems:
- 1A = 693 VA
- 5A = 3,464 VA
- 10A = 6,928 VA
🎯 Your calculations should align with these standard values.
VA ratings are crucial for:
- UPS System Sizing:1000 VA UPS = 4.35A at 230V
- Transformer Selection:5000 VA = 21.7A at 230V
- Circuit Breaker Sizing:3680 VA = 16A at 230V
💡 VA ratings help ensure proper equipment sizing and protection.
