Calculate the apparent power (kVA) or real power (kW) of a 3-phase electrical system.
Apparent Power (kVA)
Real Power (kW)
Result:
Understanding 3-Phase Power Calculations
Three-phase power systems are the backbone of industrial and commercial electricity distribution due to their efficiency and ability to deliver constant power. Unlike single-phase systems, they utilize three alternating currents that are offset in phase by 120 degrees. This design allows for smaller, more efficient motors and more uniform power delivery.
The Formulas
Calculating power in a 3-phase system involves understanding the relationship between line voltage (VL), line current (IL), and the power factor (PF). The power factor represents the ratio of real power (delivered to the load) to apparent power (total power supplied).
Apparent Power (S)
Apparent power is the total power that appears to be supplied to the circuit. It is measured in Volt-Amperes (VA) or kiloVolt-Amperes (kVA). The formula for apparent power in a balanced 3-phase system is:
S = √3 * VL * IL
Where:
S is the apparent power in VA.
√3 (approximately 1.732) is the square root of 3, a constant for 3-phase systems.
VL is the line-to-line voltage (voltage measured between any two lines).
IL is the line current (current flowing through any one line conductor).
To convert VA to kVA, divide the result by 1000.
Real Power (P)
Real power, also known as active or true power, is the actual power consumed by the load and converted into useful work (like heat or mechanical motion). It is measured in Watts (W) or kilowatts (kW). The formula for real power in a balanced 3-phase system, considering the power factor, is:
P = √3 * VL * IL * PF
Where:
P is the real power in Watts.
√3 is approximately 1.732.
VL is the line-to-line voltage.
IL is the line current.
PF is the power factor (a value between 0 and 1).
To convert Watts to kilowatts (kW), divide the result by 1000.
Use Cases
This calculator is essential for a variety of applications:
Electrical Design: Determining the required capacity of transformers, generators, and switchgear for industrial facilities.
Motor Sizing: Calculating the power consumption of 3-phase electric motors.
Load Analysis: Understanding the power demands of equipment and facilities.
Safety and Compliance: Ensuring electrical systems are adequately sized and operated within their limits.
Energy Management: Estimating energy consumption and costs.
Accurate 3-phase power calculations are crucial for ensuring the efficiency, reliability, and safety of electrical installations.
function calculatePower() {
var voltageInput = document.getElementById("voltage");
var currentInput = document.getElementById("current");
var powerFactorInput = document.getElementById("powerFactor");
var outputUnitSelect = document.getElementById("outputUnit");
var errorMessageDiv = document.getElementById("errorMessage");
var resultsContainer = document.getElementById("resultsContainer");
var resultValueSpan = document.getElementById("resultValue");
var resultUnitSpan = document.getElementById("resultUnit");
// Clear previous error messages and results
errorMessageDiv.style.display = 'none';
errorMessageDiv.innerHTML = ";
resultsContainer.style.display = 'none';
// Get input values and convert to numbers
var voltage = parseFloat(voltageInput.value);
var current = parseFloat(currentInput.value);
var powerFactor = parseFloat(powerFactorInput.value);
var outputUnit = outputUnitSelect.value;
// Input validation
if (isNaN(voltage) || voltage <= 0) {
errorMessageDiv.innerHTML = 'Please enter a valid Line Voltage greater than 0.';
errorMessageDiv.style.display = 'block';
return;
}
if (isNaN(current) || current <= 0) {
errorMessageDiv.innerHTML = 'Please enter a valid Line Current greater than 0.';
errorMessageDiv.style.display = 'block';
return;
}
if (isNaN(powerFactor) || powerFactor 1) {
errorMessageDiv.innerHTML = 'Please enter a valid Power Factor between 0 and 1.';
errorMessageDiv.style.display = 'block';
return;
}
var sqrt3 = Math.sqrt(3);
var calculatedPower;
var unit;
if (outputUnit === "kVA") {
// Calculate Apparent Power (kVA)
calculatedPower = (sqrt3 * voltage * current) / 1000;
unit = "kVA";
} else { // outputUnit === "kW"
// Calculate Real Power (kW)
calculatedPower = (sqrt3 * voltage * current * powerFactor) / 1000;
unit = "kW";
}
// Display the result
resultValueSpan.innerHTML = calculatedPower.toFixed(2); // Display with 2 decimal places
resultUnitSpan.innerHTML = unit;
resultsContainer.style.display = 'block';
}