Worked Example 5 — When Not to Increase the Number of Turns

Worked Example (5) — When Not to Increase the Number of Turns 

Note that the voltage-independent equation is useful if for example we want to do a quick check to see if our core may be saturating. Suppose we are custom-designing our inductor. We have wound 40 turns on a core with an area of A = 2 cm2. Its measured inductance 

Note that we have converted the area to m2 in the above equation, because we are using the MKS version of the equation. 

For most ferrites, an operating flux density of 0.25 T is acceptable, since the saturation flux density is typically around 0.3 T. 

Based on the B and I linearity, we can also linearly extrapolate and thus conclude that the peak current in our application should under no condition be allowed to exceed (0.3/0.25) x 10 = 12 A, because at 12 A, the held will be 0.3 T, and the core will then start to saturate. 

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