| 摘要 |
The invention provides a method of on-line diagnosis of insulation degradation in a portion of underground cable comprising: i) measuring the current flow at first and second locations of the cable utilizing an optical current sensor at one of a plurality of current frequencies; ii) determining the current flow differential at said one frequency; iii) analysing the results of the current flow differential determination according to one or more of the following diagnostic analyses to assess the need for cable replacement: a) a corrosion test on the cable to ensure the safety of conducting tests thereon; b) a partial discharge analysis; and c) one of the following two diagnostics, depending on the type of insulation material: i) a harmonic current analysis if the insulation layer is cross-linked polyethylene or EPR, or ii) a tangent delta or loss angle diagnostic if the insulation layer is paper insulated lead covered or ethylene propylene rubber.
|
