CAJ | 학술논문

从电导特性的角度研究了变压器油在高场强下的预击穿过程及机制，将变压器油在不同电场下的电导机制分为3个阶段：①在电场低于0.44 kV?mm?1时，电导电流I与外施场强 E 成正的线性关系，符合欧姆定律；②电场强度在0.44～1.33 kV?mm?1范围内时，ln(I/E2)?1/E 成正比，满足Fowler-Nordheim场致发射方程，属于隧道效应电流阶段；③当油中电场强度E>1.33 kV?mm?1，I与电压的二次方U2成正比，属于空间电荷限制电流阶段，载流子视在迁移率μc约为2.93×10?3 cm2/(V?s)，当外施电场为2 kV?mm?1时，载流子流速 v 为0.586 m?s?1，电流体力学迁移率μh 约为1.5×10?3cm2?(V?s)?1。同时，对影响变压器油电导特性的温度、流体压强、油中含水等因素进行研究，试验结果表明，随着温度的升高、流体压强的减小以及油中含水量的增加，变压器油的电导电流均将明显增加。此外，对工程上关注的不同浸油程度的绝缘纸板的电导和介电特性及其影响因素进行研究，结果表明，随着浸油水平、温度和工作频率的提高，绝缘纸板的电导电流均将相应增加。
종전도특성적각도연구료변압기유재고장강하적예격천과정급궤제，장변압기유재불동전장하적전도궤제분위3개계단：①재전장저우0.44 kV?mm?1시，전도전류I여외시장강 E 성정적선성관계，부합구모정률；②전장강도재0.44～1.33 kV?mm?1범위내시，ln(I/E2)?1/E 성정비，만족Fowler-Nordheim장치발사방정，속우수도효응전류계단；③당유중전장강도E>1.33 kV?mm?1，I여전압적이차방U2성정비，속우공간전하한제전류계단，재류자시재천이솔μc약위2.93×10?3 cm2/(V?s)，당외시전장위2 kV?mm?1시，재류자류속 v 위0.586 m?s?1，전류체역학천이솔μh 약위1.5×10?3cm2?(V?s)?1。동시，대영향변압기유전도특성적온도、류체압강、유중함수등인소진행연구，시험결과표명，수착온도적승고、류체압강적감소이급유중함수량적증가，변압기유적전도전류균장명현증가。차외，대공정상관주적불동침유정도적절연지판적전도화개전특성급기영향인소진행연구，결과표명，수착침유수평、온도화공작빈솔적제고，절연지판적전도전류균장상응증가。
In this paper, the pre-breakdown process and mechanism in oil were investigated from a conduction perspective. The conduction mechanism in oil was measured with increasing electric field strength. Three stages could be clearly distinguished according to its behavior: a. at low electric field stage (E<0.44 kV·mm?1), the current through the oil I was directly proportional to the electric field E, which satisfied Ohm's law. b. at medium electric field stage (0.44 kV·mm?1<E<1.33 kV·mm?1), ln(I/E2) appeared to proportional to E?1, which met Fowler-Nordheim equation and it was tunneling effect current. c. at high electric field stage (E>1.33 kV·mm?1), the obtained I-V2 characteristics behaved linearly, which could be explained by space-charge limited current. The apparent carrier mobilityμc in oil, carrier velocity v and hydrodynamic mobilityμh were 2.93×10?3 cm2(V·s) ?1, 0.586 m·s?1, and 1.5×10?3 cm2·(V·s)?1, respectively. Besides, the main factors affecting the conduction current in oil, including temperature, hydrostatic pressure, moisture were analyzed. Moreover, conduction current and dielectrical property versus oil-immersed levels of insulation paper and their effect factor were studied. The results indicated that with the increase in oil-immersed level, temperature and frequency spectrum, the conduction current would increase.