{"id":3005,"date":"2025-06-25T02:22:11","date_gmt":"2025-06-25T02:22:11","guid":{"rendered":"https:\/\/grwinding.com\/?p=3005"},"modified":"2025-06-25T03:03:45","modified_gmt":"2025-06-25T03:03:45","slug":"cose-il-fattore-di-apertura-della-bobina","status":"publish","type":"post","link":"https:\/\/grwinding.com\/it\/what-is-a-coil-span-factor\/","title":{"rendered":"Che cosa \u00e8 il fattore di apertura della bobina nelle macchine elettriche?"},"content":{"rendered":"\t\t
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If you’re working with electric motors<\/strong>, generators<\/strong><\/a>, or transformers<\/strong>, you’ve probably heard of the coil span factor<\/strong>\u2014also known as the pitch factor or chording factor. This small but powerful concept plays a big role in how efficiently your machine generates voltage.<\/p>

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By tweaking the coil span<\/strong>, engineers can influence not only voltage levels, but also waveform quality, machine size, and energy losses. In this guide, we’ll break down what coil span factor means and why it matters in real-world applications.<\/p>

What Is Coil Span Factor?<\/h2>

\"Diagram

The coil span factor (KC)<\/strong>\u2014also called the pitch factor or chording factor\u2014measures how effectively a coil generates voltage based on its span. It’s defined as the ratio of voltage produced by a short-pitch coil to that of a full-pitch coil<\/a><\/strong>. The formula is:<\/p>

KC = cos(\u03b1 \/ 2)<\/strong>
Where \u03b1<\/strong> is the angle by which the coil span is shortened in electrical degrees<\/strong>.<\/p>

A full-pitch coil<\/strong> spans 180\u00b0 electrical, so KC = 1<\/strong>\u2014meaning both coil sides generate in-phase voltage for maximum output. In contrast, a short-pitch coil<\/strong> (less than 180\u00b0) results in KC < 1<\/strong>, as the voltages from each side are slightly out of phase.<\/p>

Why does this matter? A smaller KC slightly reduces voltage<\/a> output, but it can also improve efficiency by reducing harmonic distortion and saving copper wire. That trade-off often makes short-pitch coils a smart design choice in modern electrical machines.<\/p>

Full-Pitch vs. Short-Pitch Coils<\/h2>

\"Diagram

Full-pitch coils<\/strong> produce maximum voltage by keeping both coil sides in phase, while short-pitch coils<\/strong><\/a> reduce voltage slightly but improve waveform quality and save materials.<\/p>

Choosing between them depends on whether output voltage or efficiency and compact design is the priority.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Feature<\/td>Full-Pitch Coil (180\u00b0)<\/td>
Short-Pitch Coil (<180\u00b0)<\/div><\/div><\/td><\/tr>
Voltage Output<\/td>Higher<\/td>Lower<\/td><\/tr>
Coil Side Phase<\/td>In-phase<\/td>Out-of-phase<\/td><\/tr>
Harmonic Distortion<\/td>Higher<\/td>Reduced<\/td><\/tr>
Material Usage<\/td>More copper<\/td>Less copper<\/td><\/tr>
Application Focus<\/td>Maximum efficiency<\/td>
Space-saving, waveform quality<\/div><\/div><\/td><\/tr><\/tbody><\/table>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Benefits of Short-Pitch Coils<\/h2>

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Using short-pitch (chorded) coils<\/strong> comes with several advantages:<\/p>