453 



Table 539 

 POWER FACTOR AND DIELECTRIC CONSTANT 



(See also Table 540 on page 454.) 



From the range of the values given, an approximate figure can be taken for a particular 

 material and its relative position with respect to other materials seen. Data of this kind are 

 much effected by the condition and past treatment of the samples, and by the conditions 

 of the tests. 



The power factor and dielectric constant of dry air may be taken as zero and 1.00. Fused 

 quartz has the lowest power factor among the solid insulating materials, and is used for 

 supporting the insulated plates of standard air condensers. 



TABLE 539. — Values for Power Factor in Per Cent for Several Electrical 

 Insulating Materials at Radio-Frequencies 



Material 



Frequency 

 kc 



Measurements reported by — 

 234 



Hard rubber. 



Amber 187., 



300 



600 



1000 



Glass 30 



600 



Cobalt glass 500 



Flint glass 500 



890 



Plate glass 14 



100 

 500 



635 

 1000 



Pyrex glass 14 



30 

 100 

 420 

 500 

 750 

 Photographic 100 



glass 235 



1700 



135 



315 



600 



625 



710 



1000 



1085 



1126 



Marble 80-650 



Mica 600 



Laminated | d 



phenolic • I0 £ 



insulation! 

 Moulded d 



phenolic • IOOO 



insulationj 

 Wood (oak) 300 



635 

 1060 



(maple) 500 



(birch) 500 



(baywood) .... 870 



Paraffin 14 



100 



500 



1070 



0-459 

 .476 



•495 

 •513 



0.040-0 



.62 



^68 



.017 



653" 



70 



4- 1 

 4" 



70 



4- 1 



05 



3-85-7 

 4.20-6 



3-68 



3-85 

 4.20 



3-33 

 6.48 



o.35 



0.56 



042 

 031 

 026 



0.26 



45 



86 



77 

 68 

 70 



70 



•74 



0.35 -4.72 

 .007- .93 



2.62- 8.0 

 3-85" 5-6 



1. 64-10. 9 

 1.56- 8.4 



13.8, 2.94" 

 10.1, 3.24 s 



63 

 76 

 017 

 034 



(1) Schott, Erich, Hochfrequenzverluste von Glasern und einigen anderen Dielektricis. Jahrb. Draht- 

 losen Tele. u. Tele., 18, 82-122, August, 1021. (2) Hoch, E. T. Power losses in insulating materials. 

 Bell System Tech. Journ., 1, No. 2, Nov., 1922. (3) MacLeod, H. J. Power losses in dielectrics. Phys. 

 Rev., 21, 53-73, 1923. (4) Decker, William C, Power losses in commercial glasses. Electr. World, 89, 

 601-603, March 19, 1927. (5) Data from the Bureau of Standards. 



a Range of 27 samples. b Range of 9 samples. c Range of 10 samples. d Range of severalsamples. 

 drying 48 hours at 8o°C. ' Range of a number of samples from different localities. 



Smithsonian Tables 



After 



