4. High voltage electrical appliances for electric power

In the operation of high-voltage electrical appliances, sometimes intermittent mechanical stress, tension, pressure, torque, as well as atmospheric overvoltage and internal overvoltage, therefore, the insulation materials used to be strong and tight, the role of air, moisture stability, rated operating voltage under the discharge amount is small, and has a high electric shock wear, arc resistance and mechanical strength.

In the modern high-voltage and ultra-high-voltage circuit breaker and full combination of electrical appliances, the use of six sulfur fluoride so-called "full insulation" (fully sealed) system, in this insulation system, the more suitable insulation material is: polyvinyl vinegar fiber impregnated epoxy resin (liquid) hot-pressing molding products, Non-filled epoxy resin casting body and PTFE plastic insulation 0, components. can refer to environmental protection heat shrinkable casing

5. High frequency electrical Appliances

In high frequency electrical appliances, electromagnetic induction, capacitance resistance, Eddy Current, dielectric loss problems are more prominent. In addition, because of the high frequency and large heat, the electric shock of the insulator is required to wear high strength, the media loss is small, the dielectric constant is stable.

For high-frequency, high-voltage electrical appliances, the dielectric constant is small, does not lead to an increase in capacitance. Applicable insulation materials are: polyethylene, crosslinked polyethylene and PTFE and so on.

6. Low Frequency electrical Appliances

The requirements of low frequency electrical appliances for insulating properties are roughly the same as those of high frequencies. Only the frequency is low, the amount of heat is small. Therefore, the structure of the insulation system to simplify and reduce the size of the shape, is the main problem.

7. High and low voltage capacitors

In the high and low voltage capacitors in the dielectric, in addition to the good dielectric properties, but also the dielectric constant is higher, can produce a large capacitance. The more suitable insulating materials are silicone liquid and polypropylene film.

8. Precision Electrician only Table

Because of the high accuracy of precision electrical instrumentation, the resistance of its insulating part should be large, and can maintain long-term stability, no deformation, not affected by changes in air, temperature and humidity, to the use of silicon liquid, silicone resin, epoxy resin and other insulation is appropriate.

9. High Voltage Cable

In high voltage cable, the electric shock piercing strength of the insulator should be high and the media loss should be small, and in order to solve the problem of capacitance, the dielectric constant of the insulating system should be as small as possible. Therefore, the new development of high-voltage power cable, the use of crosslinked polyethylene, sulfur hexafluoride as an increasing number of insulation.

10. High Voltage Insulator

High voltage insulators should have sufficient tensile, tensile strength, in the long-term use of outdoor deterioration rate should be low (the annual deterioration rate is required to be less than a few parts), and can make the tower height reduction, span increase (in order to reduce the construction of the line and maintenance costs). In order to meet these requirements, the lipid ring epoxy resin combination insulator was used in the development of high strength porcelain insulators.

In general, the performance and quality of various insulating materials, in addition to meeting the basic requirements of the above types of motors and electrical appliances, should also:

(1) Under the prescribed heat resistance level, with a certain dielectric, physical and chemical properties and mechanical strength,

(2) can meet the needs of different places of use or special provisions, such as plateau, high temperature, high humidity or underwater, tropical, underground, anti-corrosion gas, anti-atomic radiation and so on.

热缩管绝缘材料在电工行业中用途(Ⅱ）

4.电力用高压电器

在运行的高压电器中，有时断时续的机械应力、张力、压力、扭力，以及大气过电压和内部过电压的作用，因此，所用的绝缘材料要结实紧密，对空气、湿气的作用稳定，额定工作电压下的放电量小，并具有高的电击穿、耐电弧及机械强度。

在现代化的高压和超高压断路器和全组合成套电器中，采用了六氟化硫的所谓“全绝缘”(完全密封)系统;在此绝缘系统中，较适宜的绝缘材料是:聚醋纤维浸渍环氧树脂(液)的热压成型制品，无填充的环氧树脂浇铸体以及聚四氟乙烯塑料的绝缘零、部件。可以参考环保热缩套管

5.高频电器

在高频电器中，电磁感应、容抗、涡流、介质损耗问题较突出。此外，由于频率高，发热量大，故要求其绝缘体的电击穿强度高，介质损耗小，介电常数稳定。

对于高频、高压的电器，则要介电常数小，不导致电容量的增大。适用的绝缘材料是:聚乙烯、交联聚乙烯及聚四氟乙烯等。

6.低频电器

低频电器对绝缘性能的要求与高频的大致相同。只是频率较低，发热量较小。故绝缘系统的结构简化、缩小外形尺寸，是主要的问题。

7.高、低压电容器

在高、低压电容器中的电介质，除了应有良好的介电性能外，还要介电常数较高，能产生大的电容量。较适宜的绝缘材料是有机硅液和聚丙烯薄膜等。

8.精密电工仅表

由于精密电工仪表的工作准确度高，其绝缘部分的电阻要大，并能保持长期性的稳定，不变形，不受空气、温度和湿度变化的影响;以采用硅液、有机硅树脂、环氧树脂等的绝缘为宜。

9.高压电缆

在高压电缆中，绝缘体的电击穿强度应高，介质损耗要小;此外为了解决电容量的问题，要使其绝缘系统的介电常数尽可能小。因此，新发展的高压电力电缆，采用交联聚乙烯、六氟化硫为绝缘的日益增多。

10.高压绝缘子

高压绝缘子应有足够的抗拉、抗张强度，在户外长期使用中劣化率应低(要求年劣化率在千分之几以下)，并能使杆塔高度降低、跨距增大(以减少线路的建设和维修费)。为适应这些要求，在发展高强度瓷质绝缘子的同时，采用了脂环族环氧树脂组合绝缘子。

总的来说，各种绝缘材料的性能及其质量，除了要满足上述各类型电机、电器的基本要求外，还应:

(1)在规定的耐热等级下，具有一定的介电、理化性能和机械强度，

(2)可满足不同使用场所或特殊规定，如高原、高温、高湿度或水下、热带、地下、防腐蚀气体、防原子能辐射等所提出的需要。