A new method for on-line cable tanδ monitoring

the dielectric loss factor (tanδ) can reflect the insulation condition of power cables effectively. Existing methods for online tanδ monitoring require high precision synchronized phase angle data, creating difficulty in practical application. This paper proposes a new on-line cable tanδ monitoring method without the need of phase angle information. The proposed method employs a device with an adjustable impedance to generate compensative current that has the same amplitude as the capacitive component of the cable leakage current, but opposite phase angle. By doing so, the resistive and capacitive components of the cable leakage current can be separated for tanδ calculation. Simulation studies of four different cable insulation conditions are conducted for verifying the effectiveness of the proposed approach.