Dielectric response measurement as diagnostic tool for power cable systems

摘要

Information about moisture content contained within oil-paper insulated cable can be found at high frequencies where the minimum of the response occurs. Increase in moisture content not only affects the value of tan delta_(min) but also the frequency at which this minimum value occur. Apart from moisture, temperature is another factor that affects the frequency at with tan delta_(min) value occurs. Interestingly, magnitude of tan delta_(min) remains stable with temperature. Using some part of previous work, an expression that relates moisture content and time is derived. Further work is required on the practical applicability of this formula. Only cable that has been seriously affected by moisture cable can be detected by measuring tan delta at low frequencies.