電纜生產(chǎn)中經(jīng)常會(huì)遇到絕緣電阻小的現(xiàn)象,影響電纜絕緣電阻值的因素很多。實(shí)際上,主要有四個(gè)因素對(duì)絕緣電阻系數(shù)有很大影響。

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.溫度的影響.

1、 The influence of temperature

隨著溫度升高,絕緣電阻系數(shù)降低。這是由于熱運(yùn)動(dòng)的增加,離子的產(chǎn)生和遷移增加。在電壓作用下,離子運(yùn)動(dòng)形成的傳導(dǎo)電流增加,絕緣電阻降低。理論和實(shí)踐表明,絕緣電阻系數(shù)隨溫度的升高呈指數(shù)下降,電導(dǎo)隨溫度的升高呈指數(shù)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、電場(chǎng)強(qiáng)度的影響

2、 Influence of electric field intensity

當(dāng)電場(chǎng)強(qiáng)度在相對(duì)較低的范圍內(nèi)時(shí),離子的遷移率以成比例的關(guān)系隨著電場(chǎng)強(qiáng)度的增加而增加。離子電流和電場(chǎng)強(qiáng)度遵循歐姆定律。當(dāng)電場(chǎng)強(qiáng)度相對(duì)較高時(shí),隨著電場(chǎng)強(qiáng)度的增加,離子的遷移率逐漸從線性關(guān)系變?yōu)橹笖?shù)關(guān)系。當(dāng)電場(chǎng)強(qiáng)度接近擊穿時(shí),會(huì)發(fā)生大量的電子遷移,從而絕緣電阻系數(shù)大大降低。標(biāo)準(zhǔn)中規(guī)定的各種電線電纜產(chǎn)品的耐壓試驗(yàn)電壓處于離子遷移率與電場(chǎng)強(qiáng)度成比例增加的階段,因此電場(chǎng)強(qiáng)度對(duì)絕緣電阻系數(shù)的影響無法反映。當(dāng)試樣進(jìn)行擊穿試驗(yàn)時(shí)，電場(chǎng)對(duì)絕緣電阻系數(shù)的影響得到明顯反映。

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.濕度的影響

3、 Influence of humidity

由于水的導(dǎo)電性大,水分子的尺寸比聚合物分子小得多,在熱量的作用下,聚合物大分子和組成鏈節(jié)相對(duì)移動(dòng),使得水分子可以容易地滲透到聚合物中,增加聚合物中的導(dǎo)電離子。降低絕緣電阻。該標(biāo)準(zhǔn)規(guī)定了各種電線和電纜的浸泡試驗(yàn)。例如,在測(cè)量絕緣電阻之前,橡膠試件在水中浸泡24小時(shí)。目的是滿足使用過程中水分和水對(duì)電氣性能的影響。絕緣電阻是絕緣材料的主要電氣性能之一, 也是電線電纜產(chǎn)品或材料的重要指標(biāo)。通常,絕緣電阻要求不低于某個(gè)值。如果電氣成套廠家絕緣電阻值太低,沿電線和電纜線路的泄漏電流將不可避免地增加,導(dǎo)致電能的浪費(fèi)。同時(shí),電能將變成熱能,為熱擊穿做好準(zhǔn)備,增加熱擊穿的可能性。

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.材料純度的影響

4、 Influence of material purity

雜質(zhì)混入材料中,增加了材料中的導(dǎo)電顆粒,降低了絕緣電阻。因此,某種橡塑材料的絕緣電阻將反映材料的純度,并驗(yàn)證其是否符合標(biāo)準(zhǔn)。

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.

電線電纜生產(chǎn)過程中,工藝不嚴(yán)格遵守操作規(guī)程,混合雜質(zhì)和材料因受潮起泡,絕緣芯偏差或外徑尺寸小于標(biāo)準(zhǔn),絕緣分層或裂紋,絕緣劃痕等。會(huì)降低產(chǎn) 品的絕緣電阻。

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,為了檢查絕緣電阻,有必要檢查工藝操作中是否有任何問題。

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

在電線電纜的使用過程中,測(cè)量絕緣電阻的變化也可以檢查絕緣損壞情況,防止事故發(fā)生。

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