Comments on the definition of AC capacitance in ASTM-D150-81

The definition of capacitance in ASTM D150-81 is improved by considering the definition of complex capacitance. It is concluded that since the practical capacitor always has losses, it can be suitably represented by complex capacitance. The complex capacitance is closely related to relative complex permittivity, so that the concept of complex capacitance is very important in technology, and an accurate definition of complex capacitance is necessary for electrical engineering.<>