1、對金屬材料的影響溫度升高,金屬材料軟化,機械強度將明顯下降。例如,銅金屬材料長期工作溫度超過200℃時,機械強度明顯下降;短時工作溫度超過300℃時,機械強度也明顯下降,鋁金屬材料的機械強度也與溫度密切相關。通常,鋁的長期工作溫度不宜超過90℃,短時工作溫度不宜超過120℃。
1. Effect on metal materials: with the increase of temperature, the metal materials will soften and the mechanical strength will decrease significantly. For example, when the long-term working temperature of copper metal materials exceeds 200 ℃, the mechanical strength decreases significantly; When the short-time working temperature exceeds 300 ℃, the mechanical strength also decreases significantly, and the mechanical strength of aluminum metal materials is also closely related to temperature. Generally, the long-term working temperature of aluminum should not exceed 90 ℃, and the short-term working temperature should not exceed 120 ℃.
2、對電接觸的影響電接觸不良是導致許多電氣設備故障的重要原因,而電接觸部分的溫度對電接觸的良好性影響極大,溫度過高,電接觸兩導體表面會劇烈氧化,接觸電阻明顯增加,造成導體及其附件(零部件)溫度升高,甚可能使觸頭發(fā)生熔焊。由彈簧壓緊的觸頭,在溫度升高后,彈簧壓力降低,電接觸的穩(wěn)定性更差,更容易造成電氣故障。
2. Impact on electrical contact poor electrical contact is an important cause of many electrical equipment failures, and the temperature of the electrical contact part has a great impact on the good performance of the electrical contact. If the temperature is too high, the surfaces of the two conductors in the electrical contact will oxidize violently, and the contact resistance will increase significantly, resulting in the increase of the temperature of the conductor and its accessories (parts), and even the fusion welding of the contact. For the contact pressed by the spring, after the temperature increases, the spring pressure decreases, the stability of the electrical contact is worse, and it is easier to cause electrical failure.
3、對絕緣材料的影響溫度過高,有機絕緣材料將會變脆老化,絕緣性能下降,甚擊穿,材料的使用壽命也將縮短。例如,A級絕緣材料在一定溫度范圍內,每增加8—10℃,材料的使用壽命約縮短50%。因此對電機類設備存在較大影響;溫度過高,對無機絕緣材料的絕緣性能也有明顯影響。如,電瓷的擊穿強度在溫度為80℃以下時約為250kv/mm。到100℃時,其擊穿強度約為100kv/mm。
3. If the temperature of the insulating material is too high, the organic insulating material will become brittle and aging, the insulation performance will decline, even breakdown, and the service life of the material will be shortened. For example, the service life of class a insulating material is shortened by about 50% for every 8-10 ℃ increase in a certain temperature range. Therefore, it has a great impact on motor equipment; If the temperature is too high, it also has a significant impact on the insulation performance of inorganic insulating materials. For example, the breakdown strength of electric porcelain is about 250kV / mm when the temperature is below 80 ℃. At 100 ℃, the breakdown strength is about 100 kV / mm.
4、對電子元器件的影響高溫是許多電子元器件的大敵,如高溫可使半導體元件熱擊穿,因為溫度升高,電子程度加劇,使本來不導電的半導體層導通。高溫使電子元器件的性能變劣,如在偏高酌溫度下,電子元件的反向導電電流增加,放大倍數(shù)減小等。
4. Influence on electronic components high temperature is the great enemy of many electronic components. For example, high temperature can cause thermal breakdown of semiconductor components. Because the temperature increases, the degree of electronic activation intensifies, making the originally non-conductive semiconductor layer conductive. High temperature deteriorates the performance of electronic components. For example, under high temperature, the reverse conductive current of electronic components increases and the magnification decreases.
5、按國標設計和制造的電氣設備運行時周圍環(huán)境溫度的上限值不應超過40℃,而盛夏暴露在烈日中的運行配電箱,由于太陽光的直射、水泥地面熱量的反射以及箱內設備自身產生的熱量, 有時箱內的溫度竟超過60℃。如此高的溫度極易造成電器線圈、引線的絕緣老化而擊穿燒壞。電器觸頭因溫度過高而增加接觸電阻,接觸電阻增加又加劇發(fā)熱,如此惡性循環(huán)終導致觸頭燒壞;同時溫度過高還會影響電器保護性能的穩(wěn)定性、動作的可靠性、計量的準確性。
5. When the electrical equipment designed and manufactured according to the national standard operates, the upper limit of the ambient temperature shall not exceed 40 ℃. For the operation distribution box exposed to the hot sun in midsummer, sometimes the temperature in the box exceeds 60 ℃ due to the direct sunlight, the reflection of the heat of the cement ground and the heat generated by the equipment in the box. Such a high temperature can easily cause the insulation aging of electrical coils and leads to breakdown and burn out. The contact resistance of electrical contacts increases due to too high temperature, and the increase of contact resistance intensifies heating. Such a vicious cycle eventually leads to contact burnout; At the same time, too high temperature will also affect the stability of electrical protection performance, the reliability of action and the accuracy of measurement.
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