| 摘要 |
PROBLEM TO BE SOLVED: To achieve a highly sensitive measurement of partial discharge by reducing the effect of noises and improving S/N ratio. SOLUTION: A noise blocking impedance Zd is connected to between a sheath (shielding layer) near an insulation connection part IJ, at which a partial discharge detector 2 of a power cable line 1 is mounted, and the ground. When a noise voltage (e) travels on the cable line from a noise source and invades into the insulation connection part IJ, a noise voltage e1 passing through the noise blocking impedance Zd changes as shown by the following formula: e1=Γte, whereinΓt=2Zd/(2Zd+Zs). Thus, the noise blocking impedance Zd is connected to between the sheath and the ground to allow reduction in noise invading into the partial discharge detector 2 thereby improving the S/N ratio of a partial discharge signal.
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