.calculator-container {
max-width: 600px;
margin: 0 auto;
padding: 20px;
background-color: #f9f9f9;
border: 1px solid #ddd;
border-radius: 8px;
box-shadow: 0 4px 6px rgba(0,0,0,0.1);
font-family: Arial, sans-serif;
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #333;
}
.form-group input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.form-group .help-text {
font-size: 12px;
color: #666;
margin-top: 4px;
}
.calc-btn {
display: block;
width: 100%;
padding: 12px;
background-color: #0073aa;
color: #fff;
border: none;
border-radius: 4px;
font-size: 18px;
cursor: pointer;
transition: background-color 0.3s;
}
.calc-btn:hover {
background-color: #005177;
}
.result-box {
margin-top: 20px;
padding: 15px;
background-color: #e7f4e4;
border: 1px solid #c3e6cb;
border-radius: 4px;
text-align: center;
display: none;
}
.result-value {
font-size: 24px;
font-weight: bold;
color: #2c662d;
}
.result-label {
font-size: 14px;
color: #555;
}
.error-msg {
color: #d8000c;
background-color: #ffd2d2;
padding: 10px;
margin-top: 10px;
border-radius: 4px;
display: none;
text-align: center;
}
.article-content {
max-width: 800px;
margin: 40px auto;
font-family: Arial, sans-serif;
line-height: 1.6;
color: #333;
}
.article-content h2 {
color: #0073aa;
margin-top: 30px;
}
.article-content ul {
margin-left: 20px;
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.formula-box {
background-color: #f1f1f1;
padding: 15px;
border-left: 4px solid #0073aa;
font-family: monospace;
margin: 20px 0;
}
function calculateKVAtoKW() {
// Get input values using var
var kvaValue = document.getElementById('kvaInput').value;
var pfValue = document.getElementById('pfInput').value;
// Get result elements
var resultBox = document.getElementById('resultBox');
var kwResult = document.getElementById('kwResult');
var errorBox = document.getElementById('errorBox');
var displayKva = document.getElementById('displayKva');
var displayPf = document.getElementById('displayPf');
// Parse values
var kva = parseFloat(kvaValue);
var pf = parseFloat(pfValue);
// Clear previous states
resultBox.style.display = "none";
errorBox.style.display = "none";
// Validation Logic
if (isNaN(kva) || kva < 0) {
errorBox.innerHTML = "Please enter a valid positive number for Apparent Power (kVA).";
errorBox.style.display = "block";
return;
}
if (isNaN(pf) || pf 1) {
errorBox.innerHTML = "Power Factor must be a number between 0.0 and 1.0.";
errorBox.style.display = "block";
return;
}
// Calculation Formula: kW = kVA * PF
var kw = kva * pf;
// Formatting results (rounding to 3 decimal places for precision)
kw = Math.round(kw * 1000) / 1000;
// Display Logic
kwResult.innerHTML = kw + " kW";
displayKva.innerHTML = kva;
displayPf.innerHTML = pf;
resultBox.style.display = "block";
}
Understanding kVA to kW Conversion
Converting Kilovolt-Amperes (kVA) to Kilowatts (kW) is a fundamental calculation in electrical engineering, particularly when sizing generators, transformers, and UPS systems. While both units measure power, they represent different aspects of an electrical circuit.
The Difference Between kVA and kW
- kVA (Kilovolt-Amperes): This is the "Apparent Power." It represents the total amount of power being drawn by a system, combining both the working power and the reactive power. It is the vector sum of kW and kVAR.
- kW (Kilowatts): This is the "Real Power" or "Working Power." It represents the actual power that performs useful work, such as creating heat, light, or motion.
The Formula
The relationship between Apparent Power (kVA) and Real Power (kW) is defined by the Power Factor (PF). The formula is straightforward:
kW = kVA × PF
Where:
- kW: Real Power in Kilowatts
- kVA: Apparent Power in Kilovolt-Amperes
- PF: Power Factor (a decimal between 0.0 and 1.0)
What is Power Factor?
Power Factor is a measure of electrical efficiency. It represents the ratio of Real Power (kW) to Apparent Power (kVA). In a perfectly efficient system (resistive load), the Power Factor is 1.0 (or 100%), meaning all kVA is converted to kW. However, due to inductive loads like motors and transformers, some power is "lost" to creating magnetic fields, lowering the Power Factor.
Common Power Factor Values:
- 1.0: Purely resistive loads (Heaters, Incandescent bulbs).
- 0.8: Standard industrial estimation for generators and motors.
- 0.6 – 0.7: Older motors or inductive loads without correction.
Calculation Example
Let's say you have a diesel generator rated at 125 kVA and the connected load has a power factor of 0.8. To find the actual working power (kW) available:
125 kVA × 0.8 PF = 100 kW
This means your 125 kVA generator can only provide 100 kW of real power to your equipment.
Why This Matters
Understanding this conversion is critical for preventing equipment overload. If you size a generator based solely on kW without accounting for the Power Factor, you may underestimate the kVA required, potentially tripping breakers or damaging the power source.