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. 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. 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. 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. 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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