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1、,第3章 液体的绝缘特性与介质的电气强度 Chapter 3 Insulating Characteristic and Electric Intensity of Liquid Dielectrics,液体电介质又称绝缘油，在常温下为液态，在电气设备中起绝缘、传热、浸渍及填充作用，主要用在变压器、油断路器、电容器和电缆等电气设备中。在断路器和电容器中的绝缘油还分别有灭弧和储能作用。 Liquid dielectric also called insulating oil, in the state of liquid at normal temperature, which has the
2、function of insulation, heat transmission, dipping, and padding .It is mainly used in the electric equipment like transformer, oil breaker, capacitor and cable, etc. The insulating oil in breaker and capacitor also has an effect of arc extinguishing and energy storing.,液体电介质电气强度比气体的高；用液体介质代替气体介质制造的高
3、压电气设备体积小，节省材料；液体介质大多可燃，易氧化变质，导致电气性能变坏。 The intensity of liquid dielectric is higher than gas. The high-voltage electrical equipment can be smaller as well as saving material by using of liquid medium rather than gas. Most liquid medium is combustive, oxidized and deteriorated easily, which leads to
4、worse electric intensity.,电气设备对液体介质的要求： The requirement of electric equipment to liquid medium: 电气性能好，如绝缘强度高、电阻率高、介质损耗及介电常数小（电容器则要求介电常数高）； Favorable electric properties, such as high insulating intensity and resistivity, low dielectric loss and small dielectric constant(while capacitor with large di
5、electric constant); 散热及流动性能好，即粘度低、导热好、物理及化学性质稳定、不易燃、无毒等。 Excellent heat dissipation and liquidity, that is lower viscosity, good heat conductivity, stable physical and chemical nature, non-inflammability, and non-toxic.,液体电介质有矿物绝缘油、合成绝缘油和植物油三大类。实际应用中，也常使用混合油，即用两种或两种以上的绝缘油混合成新的绝缘油，以改善某些特性，例如耐燃性、析气性、自
6、熄性、局部放电特性等。 Liquid dielectric can be categorized as mineral oil, synthetic insulating oil and plant oil. Also, mixed oil is used in practical application, that means two or more kinds of insulating oil mixed together to become a new one, in order to improve some performances like flame resistance, d
7、egassing property, self-extinguishing and partial discharge, etc. 本章主要从极化、电导、损耗和击穿等多方面介绍液体电介质的绝缘特性。 This chapter mainly introduces the insulating performances of liquid dielectric from several respects such as polarization, conductance, loss, and breakdown.,3.1液体电介质的极化与损耗 3.1 Polarization and loss of liquid dielectrics 3.2液体电介质的电导 3.2 Conductance of liquid dielectrics 3.3液体电介质的击穿 3.3 Breakdown in liquid dielectrics 习题与思考题 Exercises & FAQs,本章内容 Contents in this section,
