GuideCalculatorDetailed Guide

How to Build a 3 Phase Calculator

A 3-phase power calculator determines voltage, current, and power in three-phase electrical systems. Electricians, electrical engineers, and industrial facility managers rely on it to size transformers, wire gauges, and circuit breakers correctly.

What is a 3 Phase Calculator?

Three-phase power is an AC system using three conductors carrying alternating currents offset by 120 degrees. This arrangement delivers constant power (unlike single-phase, which pulses), making it the standard for industrial motors and heavy equipment. Calculations differ depending on whether the load is wye (star) or delta connected, since line voltage and phase voltage relate differently in each configuration.

The Formula

Star (Wye) connection:
  Line Voltage = Phase Voltage × √3
  Line Current = Phase Current
  P = √3 × V_line × I_line × cos(φ)

Delta connection:
  Line Voltage = Phase Voltage
  Line Current = Phase Current × √3
  P = √3 × V_line × I_line × cos(φ)

Apparent Power (S) = √3 × V_line × I_line (in VA)
Reactive Power (Q) = √3 × V_line × I_line × sin(φ) (in VAR)

Code Example

JavaScript
function calculate3Phase({ voltage, current, powerFactor, connection }) {
  const sqrt3 = Math.sqrt(3);
  const phi = Math.acos(powerFactor);

  // Real power in watts
  const realPower = sqrt3 * voltage * current * powerFactor;
  // Apparent power in VA
  const apparentPower = sqrt3 * voltage * current;
  // Reactive power in VAR
  const reactivePower = sqrt3 * voltage * current * Math.sin(phi);

  // Phase values depend on connection type
  const phaseVoltage = connection === 'wye' ? voltage / sqrt3 : voltage;
  const phaseCurrent = connection === 'delta' ? current / sqrt3 : current;

  return { realPower, apparentPower, reactivePower, phaseVoltage, phaseCurrent };
  }

How to Build It

  1. 1

    Create inputs for line voltage, line current, power factor, and a wye/delta toggle

  2. 2

    Implement the √3 relationships for both star and delta configurations

  3. 3

    Calculate and display real power (W), apparent power (VA), and reactive power (VAR)

  4. 4

    Add a power triangle visualization showing the relationship between P, S, and Q

  5. 5

    Include a wire sizing reference table based on the calculated current and NEC standards

Key Features to Include

Toggle between wye (star) and delta configurations with automatic recalculation

Power triangle diagram showing real, apparent, and reactive power visually

Support for both balanced and unbalanced loads (per-phase current inputs)

Wire gauge recommendation based on calculated current and NEC/IEC tables

Unit conversion between watts, kilowatts, horsepower, and BTU/hr

Monetization Strategies

Freemium model with basic calculations free, NEC lookup tables and wire sizing behind a paywall

Electrical contractor lead generation (partner with panel and breaker suppliers)

Sell a companion mobile app for on-site calculations without internet

Offer a bulk calculation API for electrical design software integrations

Recommended Tech Stack

Frontend

React with an SVG-based power triangle diagram and unit conversion dropdowns

Backend

Client-side only. All formulas run in the browser with zero latency.

Hosting

Static site on Cloudflare Pages for fast global delivery

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