MEASURING METHOD FOR DIELECTRIC LOSS TANGENT OF INSULATOR, AND DIAGNOSTIC METHOD FOR INSULATION DEGRADATION OF POWER CABLE

摘要

PURPOSE: To calculate true dielectric loss tangent by superimposing voltage components of different frequency on basic wave voltage, impressing in to an insulator sample and a reference capacitor to obtain each current flowing, and obtaining both frequency components of differential current balanced for them, and using the result, both fre quency components of the voltage and ration of both frequencies as the basis for the calculation. ;CONSTITUTION: On basic wave voltage V₁ of frequency f₁, a voltage component V_n of frequency f_n is superimposed, which is impressed from an alternating current electric supplier 1 to an insulator specimen C_x and a reference capacitor C_s, and each flowing current I_x and I_s are detected by current/voltage conversion circuits 2a, 2b. One of currents I_s is amplified to (k) times with a variable amplifier 3, and the other is converted by an integration circuit 4 into voltage V_s with equal phase to voltage V(V₁+V₂). By a differential amplifier 5, differential current I=I_x-kI_s is obtained, the current I and the voltage V_s are separated by a waveform analyzer 6 into frequency components I₁ and I_n and V_sl and amplitudes and phases of them are measured. By varying k to balance and adjust the phase of I₁ and V_sl, dielectric loss tangent is obtained from currents II and I_n, voltages V_sl and V_sn, and frequencies f₁ and f_n.;COPYRIGHT: (C)1996,JPO