Skin Depth

\delta = \sqrt{ 2 \rho / \omega \mu_r \mu_0 } . . . . . 2 / \mu_0 = 1.59e6 m/H

Material

Temp

perm.

resis.

depth (m) at frequency

K

\mu_r

\rho~~\Omega-m

60 Hz

400 Hz

1 KHz

5 KHz

20 KHz

200 KHz

3% Si Transformer Steel

300

700

5e-7

3% Si Transformer Steel

700

700?

5e-7

Aluminum

300

1

Aluminum

700

1

Copper

300

1

Copper

700

1