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Eddy Current Depth of Penetration

Table 2

 

Table 2  Chart for calculating the standard depth of penetration based on conductivity (given in megasiemens per meter or percent IACS) and frequency

Frequency	0.58 MS/m	2.9 MS/m	5.22 MS/m	7.54 MS/m	9.86 MS/m	12.18 MS/m	17.4 MS/m	23.3 MS/m
	(1% IACS)	(5% IACS)	(9% IACS)	(13% IACS)	(17% IACS)	(21% IACS)	(30% IACS)	(40% IACS)
100 Hz	66.04 mm	29.54 mm	22.02 mm	18.31 mm	16.03 mm	14.40 mm	12.07 mm	10.44 mm
	(2.600 in.)	(1.163 in.)	(0.867 in.)	(0.721 in.)	(0.631 in.)	(0.567 in.)	(0.475 in.)	(0.411 in.)
300 Hz	38.13 mm	17.04 mm	12.70 mm	10.57 mm	9.25 mm	8.33 mm	6.96 mm	6.02 mm
	(1.501 in.)	(0.671 in.)	(0.500 in.)	(0.416 in.)	(0.364 in.)	(0.328 in.)	(0.274 in.)	(0.237 in.)
500 Hz	29.54 mm	13.21 mm	9.86 mm	8.18 mm	7.16 mm	6.45 mm	5.38 mm	4.67 mm
	(1.163 in.)	(0.520 in.)	(0.388 in.)	(0.322 in.)	(0.282 in.)	(0.254 in.)	(0.212 in.)	(0.184 in.)
700 Hz	24.97 mm	11.15 mm	8.33 mm	6.93 mm	6.05 mm	5.44 mm	4.55 mm	3.94 mm
	(0.983 in.)	(0.439 in.)	(0.328 in.)	(0.273 in.)	(0.238 in.)	(0.214 in.)	(0.179 in.)	(0.155 in.)
900 Hz	22.02 mm	9.86 mm	7.34 mm	6.10 mm	5.33 mm	4.80 mm	4.01 mm	3.48 mm
	(0.867 in.)	(0.388 in.)	(0.289 in.)	(0.240 in.)	(0.210 in.)	(0.189 in.)	(0.158 in.)	(0.137 in.)
1 kHz	20.88 mm	9.35 mm	6.96 mm	5.79 mm	5.05 mm	4.55 mm	3.81 mm	3.30 mm
	(0.822 in.)	(0.368 in.)	(0.274 in.)	(0.228 in.)	(0.199 in.)	(0.179 in.)	(0.150 in.)	(0.130 in.)
3 kHz	12.07 mm	5.38 mm	4.01 mm	3.35 mm	2.92 mm	2.64 mm	2.21 mm	1.91 mm
	(0.475 in.)	(0.212 in.)	(0.158 in.)	(0.132 in.)	(0.115 in.)	(0.104 in.)	(0.087 in.)	(0.075 in.)
5 kHz	9.35 mm	4.17 mm	3.12 mm	2.59 mm	2.26 mm	2.03 mm	1.70 mm	1.47 mm
	(0.368 in.)	(0.164 in.)	(0.123 in.)	(0.102 in.)	(0.089 in.)	(0.080 in.)	(0.067 in.)	(0.058 in.)
7 kHz	7.90 mm	3.53 mm	2.64 mm	2.18 mm	1.90 mm	1.73 mm	1.45 mm	1.24 mm
	(0.311 in.)	(0.139 in.)	(0.104 in.)	(0.086 in.)	(0.075 in.)	(0.068 in.)	(0.057 in.)	(0.049 in.)
9 kHz	6.96 mm	3.12 mm	2.31 mm	1.93 mm	1.68 mm	1.52 mm	1.27 mm	1.09 mm
	(0.274 in.)	(0.123 in.)	(0.091 in.)	(0.076 in.)	(0.066 in.)	(0.060 in.)	(0.050 in.)	(0.043 in.)
10 kHz	6.60 mm	2.95 mm	2.21 mm	1.83 mm	1.60 mm	1.45 mm	1.19 mm	1.04 mm
	(0.260 in.)	(0.116 in.)	(0.087 in.)	(0.072 in.)	(0.063 in.)	(0.057 in.)	(0.047 in.)	(0.041 in.)
30 kHz	3.81 mm	1.70 mm	1.27 mm	1.07 mm	0.91 mm	0.84 mm	0.69 mm	0.61 mm
	(0.150 in.)	(0.067 in.)	(0.050 in.)	(0.042 in.)	(0.036 in.)	(0.033 in.)	(0.027 in.)	(0.024 in.)
50 kHz	2.95 mm	1.32 mm	0.99 mm	0.81 mm	0.71 mm	0.64 mm	0.53 mm	0.46 mm
	(0.116 in.)	(0.052 in.)	(0.039 in.)	(0.032 in.)	(0.028 in.)	(0.025 in.)	(0.021 in.)	(0.018 in.)
70 kHz	2.49 mm	1.12 mm	0.84 mm	0.69 mm	0.61 mm	0.53 mm	0.46 mm	0.41 mm
	(0.098 in.)	(0.044 in.)	(0.033 in.)	(0.027 in.)	(0.024 in.)	(0.021 in.)	(0.018 in.)	(0.016 in.)
90 kHz	2.21 mm	0.99 mm	0.74 mm	0.61 mm	0.53 mm	0.48 mm	0.41 mm	0.36 mm
	(0.087 in.)	(0.039 in.)	(0.029 in.)	(0.024 in.)	(0.021 in.)	(0.019 in.)	(0.016 in.)	(0.014 in.)
100 kHz	2.08 mm	0.94 mm	0.69 mm	0.58 mm	0.51 mm	0.46 mm	0.38 mm	0.33 mm
	(0.082 in.)	(0.037 in.)	(0.027 in.)	(0.023 in.)	(0.020 in.)	(0.018 in.)	(0.015 in.)	(0.013 in.)
300 kHz	1.19 mm	0.53 mm	0.41 mm	0.33 mm	0.30 mm	0.25 mm	0.23 mm	0.20 mm
	(0.047 in.)	(0.021 in.)	(0.016 in.)	(0.013 in.)	(0.012 in.)	(0.010 in.)	(0.009 in.)	(0.008 in.)
500 kHz	0.94 mm	0.41 mm	0.30 mm	0.25 mm	0.23 mm	0.20 mm	0.18 mm	0.15 mm
	(0.037 in.)	(0.016 in.)	(0.012 in.)	(0.010 in.)	(0.009 in.)	(0.008 in.)	(0.007 in.)	(0.006 in.)
700 kHz	0.79 mm	0.36 mm	0.25 mm	0.23 mm	0.20 mm	0.18 mm	0.15 mm	0.13 mm
	(0.031 in.)	(0.014 in.)	(0.010 in.)	(0.009 in.)	(0.008 in.)	(0.007 in.)	(0.006 in.)	(0.005 in.)
900 kHz	0.69 mm	0.30 mm	0.23 mm	0.20 mm	0.18 mm	0.15 mm	0.13 mm	0.10 mm
	(0.027 in.)	(0.012 in.)	(0.009 in.)	(0.008 in.)	(0.007 in.)	(0.006 in.)	(0.005 in.)	(0.004 in.)
1 MHz	0.66 mm	0.30 mm	0.23 mm	0.18 mm	0.15 mm	0.15 mm	0.13 mm	0.10 mm