^f© Tables 532-534 



(Calculated by Dr. F. W. Grover, Consulting Physicist, Bur. Standards, 1931.) 

 TABLE 532.— Resistance Ratio "F" for Isolated Round Wires 



Resistance ratio F of isolated round wire, as a function of the square root of the frequency 

 divided by the direct current resistance per 1000 ft. of conductor. 



TABLE 533.— Values of Resistance Ratio for Isolated Tubular Conductors 



t, thickness of wall of tube; d, outer diameter of tube. 



TABLE 534. — Coefficients in Formula for Proximity Factor of Equal Parallel 



Round Wires 

 The proximity factor of two equal parallel conductors may be calculated by the formula 

 _ P = 1 + [G.&/f]/[F(i - Hd 2 /s*)} 

 in which the coefficient F is to be obtained from Table 532 for the given value of f/Ro and 

 the coefficients G and H are to be taken from the table below for the given value of f/Ro- 

 In the table below the values of H apply to currents in the same direction; in the case of 

 currents in opposite directions H* is to be used. In the above formula d is the diameter of 

 the wires and 5 their axial spacing. The proximity factor for two equal parallel tubular con- 

 ductors does not differ much from the value for two solid wires with the same axial spacing 

 and a value of f/Ro one-half the value for two solid wires of the same diameter, except for 

 conductors very close together. 



Smithsonian Tables 



