Crosslinking polyethylene-insulated cable insulation diagnostic apparatus

Abstract

The invention is a cross-linked polyethylene cable insulation diagnostic instrument for diagnosing the insulation performance of cross-linked polyethylene cables. It is composed of a box body and a main circuit. circuit, function selection circuit, range selection circuit, high-voltage energy storage, current sampling circuit, high-voltage output interface, charging and discharging circuit, battery power supply, high anti-interference amplifier circuit, ammeter, voltage sampling circuit and voltmeter. The connection between the high-voltage circuits can well eliminate the measurement error caused by the leakage current generated in its own circuit and the influence of the external leakage current of the cable on the measurement accuracy by using the coaxial cable grounding shielding method. The method is easy to implement and can avoid on-site AC interference, and the diagnosis process does not damage the insulation layer of cross-linked polyethylene cables (XLPE). It has the characteristics of high measurement accuracy, high stability and strong practicability.

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 performing insulation performance diagnosis on a cross-linked polyethylene cable. Background technique [0002] Cross-linked polyethylene cable (XLPE) is a kind of cable commonly used in power systems. However, some micro-defects are inevitably produced on the insulation layer of cross-linked polyethylene cable (XLPE) during the cable manufacturing process. The mechanical stress exerted on the cable body during the construction process will also increase the number of these micro-defects. The moisture that enters the insulation layer of the XLPE cable through various means will gather at these micro-defects under the action of the electric field. This may cause water tree branch problems. These water branches continuously extend in the direction of the electric field and form a multi-branched ...

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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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