FAQS | Electric motor insulation

insulation materials

1. What are the general heat resistance grades of the motor winding insulation?

Answer: Motor winding insulation can be roughly divided into: Class A, Class E, Class B, Class F, Class H and Class C.

2. What is the allowable temperature of the six main heat-resistant grades of motor winding insulation?

Answer: The allowable temperature for the six heat-resistant grades is: A grade 105 degrees, E grade 120 degrees, B grade 130 degrees, F grade 155 degrees, H grade 180 degrees, and C grade greater than 180 degrees.

3. What are the main factors that determine the insulation structure of low-voltage motors?

Answer: Mainly the groove shape, wire embedding method, insulation material and insulation treatment process.

4. What does the high voltage motor mean?

Answer: High-voltage motors generally refer to AC motors and generators of 3KV and above.

5. How many types of insulating paint can be divided into different types?

Answer: Insulating paint can be divided into dipping paint, covering paint, Guigang lacquer, enameled wire paint, adhesive paint, etc. according to its purpose.

6. What are the two types of insulating impregnating varnish? What are their advantages and disadvantages?

Answer: Insulating impregnating varnish can be divided into two types:

1) Solvent insulation impregnating varnish.

2) Solvent-free insulating dipping varnish. The former has good permeability, long storage period and low price. It has the advantages of convenient use and production management, but the paint has the disadvantages of long drying time and slow curing when dipping the paint workpiece, and the volatilization of the solvent causes waste and environmental pollution. The latter has the advantages of fast curing, large viscosity changes with temperature, small volatiles during curing, good insulation and dielectric properties, and large paint hanging. However, the paint has disadvantages such as high price, short storage period, high viscosity, and complicated production management. .

7. What are the basic principles for the selection of insulating dipping varnish?

Answer: 1) The viscosity should be low, and the solid content should be high to facilitate penetration and filling of the impregnation. The amount of hanging paint should be large. 2) The thick layer of dipping paint cures quickly, has good drying properties, strong adhesion, and the paint film is flexible, and can withstand the centrifugal force of the motor when it is running. 3) It has good electrical properties, heat resistance, moisture resistance, oil resistance and chemical resistance, and good stability. 4) It is harmless to conductors and other insulating materials and has good compatibility. 5) The price is cheap, the materials are based in the country, the storage period is long and the toxicity is low.

8. What are the two types of curing agents for epoxy resins according to the curing temperature?

Answer: Room temperature curing agent and heating curing agent.

9. What are impregnated fiber products made of?

Answer: Use insulating fiber products as the substrate, impregnated with insulating varnish made of fiber products, such as varnished cloth, lacquer tubes and lashing tape.

10. What are the advantages and disadvantages of glass fiber? What methods are commonly used to improve its shortcomings?

Answer: Advantages: Strong resistance to tension, high heat resistance and low moisture absorption. Its disadvantages are: poor flexibility, not resistant to folding, and synthetic fibers are often interwoven or chemically treated to improve its flexibility and paint film adhesion.

11. What material is the insulating paint tube made of? What is its main function?

Answer: The insulating paint tube is made of natural fiber, synthetic fiber or alkali-free glass fiber woven into a tube, and then impregnated with insulating paint or resin, and dried to make a flexible paint tube with certain electromechanical properties. The lead wires of low voltage coils or windings, and the connecting wires between poles are insulated.

12. How are laminates made?

Answer: Laminated products are insulating materials made of fibrous products by dipping or coating different adhesives, and then hot pressing or rolling. They mainly include laminates, tubes (tubes) ), rods and special profiles, etc.

13. Insulation material inspection items can be divided into four aspects according to their performance?

Answer: According to its performance, it can be divided into four aspects: electrical, mechanical, physical and chemical and thermal performance.

14. What are the main contents of testing the electrical performance of insulating materials?

Answer: The main items are: breakdown strength, volume resistivity, surface resistivity, relative dielectric constant, dielectric loss tangent and corona resistance.

15.What are the basic principles for the selection of insulating materials?

Answer: The basic principles for the selection of insulation materials are: 1) In the design, the insulation materials with satisfactory heat resistance should be selected according to the highest actual temperature reached by different insulation parts of the motor. 2) The compatibility of the selected insulating materials is better. 3) Appropriate materials should be selected according to the stress conditions during manufacturing and operation, the level of working voltage and the working environment conditions. 4) Materials should be selected according to process conditions. 5) Under the premise of meeting the same technical requirements, choose the lowest-priced materials and materials with good workmanship. 6) Choose according to the type of insulation structure. 7) The insulating materials used should be based on domestic and abundant resources, and use as little or no materials related to the national economy and people's livelihood as possible.

16.What are the main factors considered in the design of the insulation structure of the high-voltage motor?

Answer: The design of the insulation structure of the high-voltage motor should be comprehensively considered in terms of machinery, electricity, heat, materials, technology, and environmental conditions, with electrical strength and mechanical strength as the main considerations.

17. What is the life of motor insulation?

Answer: From the moment the motor is put into operation, under long-term working conditions, the electrical and mechanical properties of the motor insulation will always deteriorate with the use of time, and finally reach the point where it cannot work reliably. People keep the insulation in normal working conditions. The elapsed time is called the life of the motor insulation.

18.What factors are related to the insulation life of the motor?

Answer: The insulation life of the motor is related to the materials used, insulation structure, insulation technology, testing methods, management level, and factors such as mechanical, electrical, thermal, chemical, environmental, and moisture in operation

19. What are the electrical properties of motor insulation?

Answer: The electrical performance of motor insulation refers to the electrical strength, corona resistance, dielectric loss tangent and its increment A t98 insulation resistance, and relative permittivity.

20. What are the factors that affect the electrical performance of the motor insulation?

Answer: There are two reasons that affect the electrical performance of the motor insulation. 1. Influencing factors in the manufacturing process, including materials, structures, process tests, etc. 2. Influencing factors during operation, including working voltage, field strength, working environment, mechanical stress, voltage frequency, working conditions and running time, etc.

21. What is the purpose of insulating materials?

Answer: The purpose of the insulating material is to isolate the charged part from the uncharged part or the part with different potentials, so that the current can flow along the route specified by people.

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