Research on Porcelain Insulator Deterioration Detection Technology

In this paper, a method for detecting the internal insulation deterioration of porcelain insulators based on impulse high voltage is proposed. The method uses the detection equipment to apply impulse high voltage to the porcelain insulators to be tested. An impulse current loop is formed between the insulators to be tested and the detection equipment. A current transformer is set in the impulse current loop. Based on the induced voltage formed on the current transformer, the normal insulator and the insulator with internal insulation deterioration can be distinguished. Using this method, the detection is carried out under the condition that the insulator to be tested is not charged and charged respectively. The results show that: (1) when the insulator is not charged, the method can reliably identify normal and zero value insulators, and the identification results are not affected by the moisture on the insulator surface; (2) When the insulator is live, the method of this study can also accurately identify the normal and zero value insulators. Firstly, the method of this study is used to carry out the detection when the DC(Direst Current) voltage with constant amplitude is applied at both ends of the insulator to be tested. The results show that when the insulator to be tested is a normal insulator, the induced voltage formed on the current transformer in the impulse current circuit is distributed between <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$404 \sim 424 \text{mV}$</tex>, and the voltage value basically does not fluctuate with the fluctuation of DC voltage amplitude at both ends of the insulator; When the insulator to be tested is a zero value insulator with internal insulation deterioration, the induced voltage formed on the current transformer in the impulse current circuit is distributed between <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1024 \sim 1156 \text{mV}$</tex>, and the voltage value basically does not fluctuate with the fluctuation of DC voltage amplitude at both ends of the insulator. Then, under the condition of applying power frequency AC(Alternating Current) voltage at both ends of the insulator to be tested, the method of this study is used to carry out the detection. The results show that when the insulator to be tested is a normal insulator, the induced voltage formed on the current transformer in the impulse current circuit is distributed between 274mV and 476mV, and the magnitude of the induced voltage in this distribution range varies with the phase of the AC voltage on the insulator to be tested when the impulse high voltage is applied; When the insulator to be tested is a zero value insulator, the induced voltage formed on the current transformer in the impulse current circuit is distributed between 980mV and 1024mV. The magnitude of the induced voltage within this distribution range is different due to the different phase of the AC voltage on the insulator to be tested when the detection impulse high voltage is applied.