This standard specifies methods for measuring dielectric properties such as relative permittivity, dielectric loss tangent, and dielectric loss factor calculated from these in the frequency range of 15 Hz to 300 MHz. Some of the measurement methods specified in this standard can also be used in frequency ranges significantly lower or higher than this frequency range, with special care.
JIS C 2138:2007 history
2007JIS C 2138:2007 Electrical insulating materials -- Methods for the determination of the relative permittivity and dielectric dissipation factor