电缆生产中经常会遇到绝缘电阻小的现象,影响电缆绝缘电阻值的因素很多。实际上,主要有四个因素对绝缘电阻系数有很大影响。

Small insulation resistance is often encountered in cable production, which is affected by many factors. In fact, there are four main factors that have a great influence on the coefficient of insulation resistance.

一.温度的影响.

1、 The influence of temperature

随着温度升高,绝缘电阻系数降低。这是由于热运动的增加,离子的产生和迁移增加。在电压作用下,离子运动形成的传导电流增加,绝缘电阻降低。理论和实践表明,绝缘电阻系数随温度的升高呈指数下降,电导随温度的升高呈指数上升。

With the increase of temperature, the insulation resistance coefficient decreases. This is due to the increase of thermal motion and the increase of ion production and migration. Under the action of voltage, the conduction current formed by ion motion increases and the insulation resistance decreases. The theory and practice show that the insulation resistance coefficient decreases exponentially with the increase of temperature, and the conductivity increases exponentially with the increase of temperature.

二、电场强度的影响

2、 Influence of electric field intensity

当电场强度在相对较低的范围内时,离子的迁移率以成比例的关系随着电场强度的增加而增加。离子电流和电场强度遵循欧姆定律。当电场强度相对较高时,随着电场强度的增加,离子的迁移率逐渐从线性关系变为指数关系。当电场强度接近击穿时,会发生大量的电子迁移,从而绝缘电阻系数大大降低。标准中规定的各种电线电缆产品的耐压试验电压处于离子迁移率与电场强度成比例增加的阶段,因此电场强度对绝缘电阻系数的影响无法反映。当试样进行击穿试验时，电场对绝缘电阻系数的影响得到明显反映。

When the electric field strength is relatively low, the mobility of ions increases in proportion with the increase of electric field strength. The ionic current and electric field strength follow Ohm's law. When the electric field intensity is relatively high, with the increase of electric field intensity, the mobility of ions gradually changes from linear relationship to exponential relationship. When the electric field is close to breakdown, a large number of electrons will migrate and the insulation resistance coefficient will be greatly reduced. The withstand voltage test voltage of various wire and cable products specified in the standard is in the stage of ion mobility increasing in proportion to the electric field strength, so the influence of electric field strength on the insulation resistance coefficient cannot be reflected. The effect of electric field on the insulation resistance coefficient is obviously reflected when the sample is subjected to breakdown test.

三.湿度的影响

3、 Influence of humidity

由于水的导电性大,水分子的尺寸比聚合物分子小得多,在热量的作用下,聚合物大分子和组成链节相对移动,使得水分子可以容易地渗透到聚合物中,增加聚合物中的导电离子。降低绝缘电阻。该标准规定了各种电线和电缆的浸泡试验。例如,在测量绝缘电阻之前,橡胶试件在水中浸泡24小时。目的是满足使用过程中水分和水对电气性能的影响。绝缘电阻是绝缘材料的主要电气性能之一, 也是电线电缆产品或材料的重要指标。通常,绝缘电阻要求不低于某个值。如果电气成套厂家绝缘电阻值太低,沿电线和电缆线路的泄漏电流将不可避免地增加,导致电能的浪费。同时,电能将变成热能,为热击穿做好准备,增加热击穿的可能性。

Due to the large conductivity of water, the size of water molecules is much smaller than that of polymer molecules. Under the action of heat, polymer macromolecules and constituent chains move relatively, so that water molecules can easily penetrate into the polymer and increase the conductive ions in the polymer. Reduce the insulation resistance. The standard specifies the immersion test of various wires and cables. For example, the rubber specimen is immersed in water for 24 hours before the insulation resistance is measured. The purpose is to meet the influence of moisture and water on electrical performance during use. Insulation resistance is one of the main electrical properties of insulating materials, and it is also an important index of wire and cable products or materials. Generally, the insulation resistance should not be lower than a certain value. If the insulation resistance value of electrical equipment manufacturers is too low, the leakage current along the wire and cable lines will inevitably increase, resulting in the waste of electric energy. At the same time, electric energy will be turned into heat energy to prepare for thermal breakdown and increase the possibility of thermal breakdown.

四.材料纯度的影响

4、 Influence of material purity

杂质混入材料中,增加了材料中的导电颗粒,降低了绝缘电阻。因此,某种橡塑材料的绝缘电阻将反映材料的纯度,并验证其是否符合标准。

The impurity mixed into the material increases the conductive particles in the material and reduces the insulation resistance. Therefore, the insulation resistance of a certain rubber plastic material will reflect the purity of the material and verify whether it meets the standard.

电线电缆生产过程中,工艺不严格遵守操作规程,混合杂质和材料因受潮起泡,绝缘芯偏差或外径尺寸小于标准,绝缘分层或裂纹,绝缘划痕等。会降低产 品的绝缘电阻。

In the process of wire and cable production, the process does not strictly comply with the operating procedures, mixed impurities and materials Blister due to moisture, insulation core deviation or outer diameter size is less than the standard, insulation delamination or crack, insulation scratch, etc. It will reduce the insulation resistance of the product.

因此,为了检查绝缘电阻,有必要检查工艺操作中是否有任何问题。

Therefore, in order to check the insulation resistance, it is necessary to check whether there are any problems in the process operation.

在电线电缆的使用过程中,测量绝缘电阻的变化也可以检查绝缘损坏情况,防止事故发生。

During the use of wires and cables, measuring the change of insulation resistance can also check the insulation damage and prevent accidents.