Apparent Power Calculator (kVA & VA)

Electrical Power Calculator

Formula:

Understanding Apparent Power: How to Calculate kVA and VA

Apparent Power Calculator

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Apparent power is a crucial concept in electrical engineering that represents the total power in an AC circuit. This guide explains how to calculate apparent power in both kVA (kilovolt-amperes) and VA (volt-amperes), with a practical online calculator and detailed formulas.

What is Apparent Power?

Apparent power combines real power (measured in watts) and reactive power (measured in VARs) in AC systems. It's calculated using the formula:

S = V × I (Single-phase)
S = √3 × V × I (Three-phase)

When to Use kVA vs VA

Unit Usage Conversion
VA (Volt-Ampere) Small electrical systems 1 VA = 1 W
kVA (Kilovolt-Ampere) Industrial equipment
Power transformers
Generators		 1 kVA = 1,000 VA

Calculation Example

Let's calculate apparent power for a three-phase system:

  • Voltage: 480V
  • Current: 25A
  • Phase: Three-phase
S = √3 × 480V × 25A 
  = 1.732 × 480 × 25 
  = 20,784 VA ≈ 20.8 kVA

Why Apparent Power Matters

  • Determines equipment sizing
  • Essential for power factor calculations
  • Crucial for electrical system design
  • Helps prevent circuit overloads

FAQs

Q: How does three-phase differ from single-phase?

A: Three-phase systems use three conductors instead of one, requiring the √3 multiplier in calculations for balanced loads.

Q: When should I use kVA instead of kW?

A: Use kVA when dealing with generators or transformers, as it represents total power including reactive components.

Q: Can I use this calculator for DC systems?

A: No - apparent power is only relevant for AC circuits. DC systems use simple P = V × I calculations.

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