YFFBGG扁电缆，带钢丝加强型CCDL

 

Influence of high voltage on insulation resistance: leakage current

 

 

 

绝缘材料在恒定电压的作用下，总有一微小的泄漏电流通过。泄漏电流的大小与材料的电导率成正比，与其绝缘电阻成反比。将一块固体绝缘材料两端加上直流电压，则流过其内部（而非表面）的电流随时间的变化趋势如下图所示所示。

 

Under the action of constant voltage, the insulating material always has a small leakage current. The leakage current is directly proportional to the conductivity of the material and inversely proportional to its insulation resistance. When DC voltage is applied to both ends of a piece of solid insulating material, the current flowing through its interior (not its surface) will change with time as shown in the figure below.

 

 

 

固体绝缘材料中的电流i与时间t的关系

 

The relationship between current I and time t in solid insulating materials

 

固体绝缘材料中的电流i与时间t的关系

 

The relationship between current I and time t in solid insulating materials

 

 

 

在接通电源的瞬间，充电电流ic可达到很高值，但迅速进入吸收电流阶段。ia是由于介质内分子、离子等的极化造成的，其大小随时间变化，也受电极形状、介质的种类以及温度等的影响。吸收电流完全衰减至一恒定电流值ig往往需要数分钟以上的时间，有的材料甚至需要几小时至几天的时间，ig称为泄漏电流，它由介质的绝缘电阻所决定。ia与ig的比值达数倍至数十倍。因此，如果在施加电压后马上测电流，并依此来计算绝缘电阻，则此电阻值显著偏小。通常测试绝缘电阻时应以施加电压1分钟或10分钟后的电流来求出。

At the moment of power on, the charging current IC can reach a very high value, but quickly enter the absorption current stage. IA is caused by the polarization of molecules and ions in the medium. Its size changes with time, and is also affected by the electrode shape, the type of medium and temperature. It usually takes more than a few minutes for the absorption current to completely decay to a constant current value Ig. Some materials even take a few hours to several days. Ig is called leakage current, which is determined by the insulation resistance of the medium. The ratio of IA to Ig is several to dozens of times. Therefore, if the current is measured immediately after the voltage is applied and the insulation resistance is calculated according to this, the resistance value is significantly smaller. Generally, the insulation resistance shall be measured by the current after applying voltage for 1 minute or 10 minutes.

 

 

 

泄漏电流对温度的高低也有反映。温度越高、泄漏电流越大，相应的绝缘电阻也越小。固体材料的绝缘电阻随温度的增加而下降。

 

The leakage current also reflects the temperature. The higher the temperature, the greater the leakage current, the smaller the insulation resistance. The insulation resistance of solid materials decreases with the increase of temperature.

 

绝缘电阻（或介质电导）的数值与电压有关，通常在介质接近击穿时，有显著的、快速增加的自由电子导电现象，这时阻值将剧烈下降。

 

The value of insulation resistance (or dielectric conductivity) is related to the voltage. Generally, when the dielectric is close to breakdown, there is a significant and rapid increase of free electron conductivity, at this time, the resistance will drop sharply.

 

如下图所示为固体介质的典型电流一电压特性。其中可划分为三个阶段。在阶段a：电压与电流的关系服从欧姆定律；在阶段b：电流与电压 几乎成指数关系；在阶段c：电流将随电压急剧增加直至击穿。

 

As shown in the figure below, typical current voltage characteristics of solid media are shown. It can be divided into three stages. In stage a, the relationship between voltage and current obeys Ohm's law; in stage B, the relationship between current and voltage is almost exponential; in stage C, the current will increase sharply with voltage until breakdown.