Common electrical materials for mechanical and ele

2022-07-27
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Mechanical and electrical engineering knowledge points of the second level constructor exam: types and applications of common electrical materials

mechanical and electrical engineering knowledge points of the second level constructor exam: types and applications of common electrical materials

16:47 source: font: size printing, The rise in popularity is all due to the gold content of the certificate of the level II constructor examination. Today, I have sorted out the mechanical and electrical engineering knowledge points of the secondary constructor examination: the types and applications of common electrical materials. I hope it can help you

1h411013 types and applications of commonly used electrical materials

I. types and applications of wires

type, bvpc/abs alloy has good finishing and adhesion to the covering film type: copper core wires are widely used in mechanical and electrical engineering

type and Rx type: copper core flexible wires are mainly used at movable parts requiring flexible connection

v type: multi-core flat or round plastic wire, which can be used for wiring in electrical equipment. It mostly appears in fixed wiring in household appliances. However, the model is not BVV hard wire for conventional lines, but RVV, which is copper core plastic insulated plastic sheathed multi-core flexible wire

II. Type and application of cable

v type: cross linked polyethylene power cable, which can not be subjected to external mechanical force, is suitable for indoor and tunnel bridge and pipeline laying

v22 type: inner steel tape armored power cable, which can bear certain external mechanical force, but can not bear large tensile force. The maximum allowable long-term temperature of yjv22 type XLPE insulated power cable is 90 ℃. High requirements for fixtures

-yjfe and NH yjfe types: flame retardant, fire-resistant and other special irradiation handover power cables are subject to social supervision. The maximum long-term allowable working temperature of the cables can reach 125 C, which can be laid in the ceiling and in the cable shaft of high-rise buildings, And suitable for wet places

the fire-resistant cable is characterized by its ability to conduct electricity when the cable is burned or even for a period of time after burning. It is mostly used in relatively important working environments, such as warships. Fire resistant cables can have fire-retardant performance at the same time, but fire-retardant cables do not have fire-resistant performance

III. types and applications of insulating materials

including insulating paint, insulating glue, gas dielectric insulating materials, liquid insulating materials, mica products and laminated products

3. Gas dielectric insulating materials: in addition to being used as insulating materials in electrical equipment, gas also has the functions of arc extinguishing, cooling and protection. Commonly used gas insulating materials include air, nitrogen, sulfur dioxide and sulfur hexafluoride

[2017 real topic] the arc extinguishing medium and insulating medium of SF6 circuit breaker are () respectively

a. gas and liquid

b. gas and gas

c. liquid and liquid

d. liquid and vacuum. SF6 is a colorless, odorless, non flammable, non explosive, non-toxic and chemically stable gas. It has a large molecular weight and contains fluorine atoms with strong electronegativity. It has good insulation and arc extinguishing properties. See textbook P10

relevant recommendations:

2018 grade II constructor examination results have been announced. The new examination season has come. We need to make a good plan for the preparation of grade II constructor examination. To prepare candidates for the new course of 2019 level II constructor examination, candidates who want to understand the course can

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