METHOD FOR DETECTING ABNORMAL PART OF DIELECTRIC LOSS TANGENT OF POWER CABLE

PURPOSE:To enable the detection of a small abnormal part, by repeating a dielectric loss tangent-voltage test for a power cable raising or lowering the voltage to judge abnormality depending on hysteresis characteristic. CONSTITUTION:A terminal wound on a drum 3 of a cable 1 is connected to a variable voltage source and a dielectric loss tangent measuring device 5 with a voltage application line 4. A test terminal 2 is fed with current and a dielectric loss tangent-voltage test is performed for the cable 1 raising the voltage gradually and then, the same test is done lowering the voltage. This test is repeated and identifies any dielectric loss tangent abnormal point in the cable when a hysteresis characteristic is recognized. This can detect any extremely small dielectric loss tangent abnormal part thereby achieving a higher reliability of the cable 1.