Crosslinking polyethylene-insulated cable insulation diagnostic apparatus

Abstract

The invention discloses a cross-linked polyethylene cable insulation diagnostic apparatus for diagnosing the insulation property of a cross-linked polyethylene cable, comprising a box body and a main circuit; the invention is characterized in that: the main circuit is composed of a voltage select circuit, a high-voltage voltage transformation circuit, a polarity select circuit, a function select circuit, a measurement range select circuit, a high-voltage accumulator, a current sensing circuit, a high-voltage output interface, a charging and discharging circuit, a battery cell power supply, a high interference resistant amplifier circuit, an ammeter, a voltage sampling circuit and a voltmeter; the high-voltage circuits of the main circuit are connected with coaxial cables earthed for shielding, which eliminates the metering error caused by leakage current generated in the loops of the cables and the influence of the leakage current outside the cables on the measuring accuracy; with the DC resistance measurement which is easy to realize, the on-site AC interference can be easily avoided and the insulating layer of the cross-linked polyethylene cable (XLPE) can not be damaged during the diagnosis.

Description

technical field [0001] The invention belongs to a diagnostic instrument in the field of power cables, in particular to a cross-linked polyethylene cable insulation diagnostic instrument for diagnosing the insulation performance of cross-linked polyethylene cables. Background technique [0002] Cross-linked polyethylene cable (XLPE) is a kind of cable commonly used in power systems, but it is inevitable to produce some microscopic defects on the insulation layer of cross-linked polyethylene cable (XLPE) during the cable manufacturing process, and in the cable The mechanical stress imposed on the cable body during construction will also increase the number of these microscopic defects, and the moisture that enters the insulation layer of cross-linked polyethylene cable (XLPE) through various methods will gather at these microscopic defects under the action of the electric field, This can lead to water tree sticking problems. These water tree branches continue to extend along ...

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Problems solved by technology

However, the current measured by this DC component current method or the ultra-low frequency current is extremely weak (generally at the nA level) and extremely unstable. A small disturbance will cause a large error, and the original battery effect cannot be completely eliminate

Therefore, the above method is only in the theoretical or laboratory stage, and does not consider or solve well the various actual interference factors of some on-site detection environments. The measurement results of the above-mentioned scheme in actual on-site conditions are easily affected by the surrounding environment. , the measured results have low precision, poor stability, and poor practicability

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