What aspects does motor insulation include? Answer: Motor insulation includes insulation between strands, tu...
Answer: Motor insulation includes insulation between strands, turns, rows, layers and ground of the coil, various insulating components used for various supports or fixations at the end, and insulation of connecting wires and lead wires.
Answer: The main insulation of the coil refers to the insulation between the coil and the fuselage and other windings, which is also called ground insulation.
Answer: Inter-turn insulation refers to the insulation between turns of the same coil.
Answer: Inter-strand insulation refers to the insulation between the strands in the same turn, which is generally the insulation of the winding electromagnetic wire itself.
Answer: Inter-row insulation is the insulation of several rows of wires connected in parallel.
Answer: The insulation structure of the motor plays an insulating role, but some also play a mechanical support and fixing role. During long-term operation, the motor insulation is affected by electrical, thermal, mechanical forces and different environmental conditions. The insulation will gradually age and eventually lose its proper performance. This leads to insulation breakdown and cannot continue to operate safely. Therefore, the reliability and life of the motor operation are largely determined by the insulation of the coil, so people compare the coil to the heart of the motor.
Answer: The basic factors for insulation damage of commonly used motor coils are the influence of heat, electricity, mechanical forces and environmental conditions.
Answer: Motor winding insulation can be roughly divided into: Class B, Class F, Class H, Class C.
Answer: Mainly slot shape, wire embedding method, insulation material and insulation treatment process.
Answer: The stator slot shape of small and medium-sized motors depends on the capacity, voltage and winding form. Small low-voltage motors generally use semi-closed slots.
Answer: High-voltage motors generally refer to AC motors and generators of 3KV and above.
Answer: It mainly determines the inter-turn insulation, slot insulation, end insulation and lead insulation.
Answer: The main insulation is usually composed of three materials: mica, reinforcement material and adhesive. The improvement of the main insulation mainly improves the heat resistance of the adhesive and the motor performance.
Answer: The two structural forms of the synchronous motor salient pole rotor coil are multi-layer multi-turn magnetic pole coil and single-layer multi-turn magnetic pole coil.
Answer: Synchronous machine hidden pole rotor coils are continuous, half-turn and single-layer concentric.
Answer: There are two types of wire embedding for wound rotor windings: loose embedding and insertion. The former is used for small motors, and the latter is used for medium and large motors.
Answer: Insulating varnishes can be divided into impregnation varnish, covering varnish, Guigang flake varnish, enameled wire varnish, adhesive varnish, etc.
Answer: Insulating impregnation varnishes can be divided into two types:
① Solvent-containing insulating impregnation varnish.
② Solvent-free insulating impregnation varnish. The former has good permeability, long storage period and low price. It has the advantages of convenient use and production management, but the varnish has the disadvantages of long baking time and slow curing when impregnating the workpiece, and the volatilization of the solvent causes waste and pollutes the environment. The latter has the advantages of fast curing, large viscosity change with temperature, small volatiles during curing, good dielectric properties, and large amount of paint, but the paint has the disadvantages of high price, short storage period, high viscosity, and complex production management.
Answer:
① The viscosity should be low and the solid content should be high to facilitate penetration and filling of the impregnated object. The amount of paint should be large.
② The thick layer of impregnating paint cures quickly, has good drying properties, strong adhesion, and the paint film is elastic and can withstand the centrifugal force during motor operation.
③ It has good electrical properties, heat resistance, moisture resistance, oil resistance and chemical resistance.
④ It is harmless to conductors and other insulating materials and has good compatibility.
⑤ It is cheap, the material is based in China, the storage period is long and the toxicity is low.
Answer:
① It has a fixed color, the paint film is smooth, flat, bright and shiny.
② It has a high degree of dispersibility. The covering power should be strong.
③ Long storage period, good stability, no cementation phenomenon.
④ The paint film has sufficient hardness and wear resistance, good mechanical properties.
⑤ The paint film has good arc resistance and dielectric properties.
⑥ The paint film has good moisture resistance, oil resistance, and chemical corrosion resistance. For the insulation covering paint for warm and hot zone motors, it should also have anti-toxicity and salt spray resistance.
⑦; For the special anti-corona covering paint used for high-voltage motors, it also has good resistance stability, uniformity and a certain resistance value.
Answer: Commonly used epoxy resins are bisphenol A type and phenolic epoxy resin.
Answer: Room temperature curing agent and heating curing agent.
Answer: Fiber products made of insulating fiber products as the base material and impregnated with insulating paint, such as varnished cloth, varnished tubes and binding tapes.
Answer: The advantages are strong tensile strength, high heat resistance, and low moisture absorption. Its disadvantages are: poor softness, not folding resistance, and synthetic fibers are often interwoven or chemically treated to improve its softness and adhesion of the paint film.
Answer: Four types of glass cloth are commonly used for coil insulation, namely: 2430 asphalt alkyd glass cloth, 2432 alkyd glass cloth, 241 polyester glass cloth, and 2450 silicone glass cloth.
Answer: Insulating paint tubes are made of natural fibers, synthetic fibers or alkali-free glass fibers woven into a tube, then impregnated with insulating paint or resin, and dried to make a kind of paint tube with certain electromechanical properties and softness. It is mainly used for the lead-out wires of low-voltage coils or windings, and the insulation of inter-pole connecting wires.
Answer: Commonly used paint tubes include 2751 silicone rubber edge glass paint tube (H grade insulation) and 2750 silicone glass paint tube (H grade insulation).
Answer: Laminated products are made of fiber products, impregnated or coated with different adhesives, and then hot-pressed or rolled to form a layered tree of insulating materials, mainly including laminated boards, tubes (tubes), rods and special profiles.
Answer: Mica.
Answer: Mica has good insulating dielectric properties, high heat resistance and chemical stability.
Answer:
① Cooked powder mica paper, which is powder mica paper produced by thermochemical method using mica scraps.
② Raw powder mica paper, which is powder mica paper produced by high-pressure water pulverization using mica scraps.
③ Large-scale mica paper, which is pure mica material, is produced by high-pressure water impact method. Powdered mica paper has larger scales.
Answer: It has the following advantages:
① Improve the utilization rate of natural mica, from the original 7%-10% to more than 80%.
② The thickness of powdered mica paper is uniform, and the thickness of the finished products is uniform, so the electrical properties are stable and the thermal conductivity is good.
③ It is conducive to the mechanized production of powdered mica products, which can improve production efficiency, reduce costs and improve working conditions.
Answer: It is mainly composed of mica, adhesives and reinforcing materials?
Answer: According to their uses, they can be divided into four categories: mica tape, mica board, mica box and mica glass.
35.What are the electrical films commonly used for coil insulation? Briefly describe their common points? What are their uses?
Answer: Commonly used electrical films are mainly 6062 polyester film, 6065 polyesterimide film and polytetrafluoroethylene film. Their common features are thin thickness, softness, moisture resistance, and good electromechanical properties.
Application: Mainly used as coil wrapping insulation, slot insulation of low-voltage motors, etc., and polytetrafluoroethylene film is often used as a demolding material for coil insulation hot pressing.
Answer: Composite products are made by bonding fiber materials on one or both sides of electrical films to make insulating materials. The purpose is to enhance the mechanical properties of the film, improve the tear strength and surface stiffness to improve the processability.
Answer: Commonly used composite products are:
①6520 polyester film insulation paper composite foil.
②6530 polyester film glass varnish cloth composite foil.
③Polyester film polyester fiber paper composite foil (DMD).
④Polyester film aromatic polyamide fiber paper composite foil (NMN).
⑤ Polyester film sulfone amide polyester non-woven composite foil (SDMSD277).
⑥ Polyimide film aromatic cluster polyamide fiber paper composite foil (NHN).
Answer: According to their performance, they can be divided into four aspects: electrical, mechanical, physical and chemical, and thermal performance.
Answer: Mainly: breakdown strength, volume resistivity, surface resistivity, relative dielectric constant, dielectric loss tangent and corona resistance.
Answer:
① Volatile content X (%) X = (G-G1) / Gx100%
② Adhesive content Y (%) Y = (G1-G2) / G1x100%
③ Mica content Z (%) Z = 100%-(Y+KxKxFxD) / G1x100%
Where G——sample weight before drying (g)
G1——sample weight after drying (g)
G2——sample weight after burning (g)
K——glass cloth standard weight (g/m²)
F——sample area (m²)
D——number of reinforcement layers.
Answer: Test tube method: Pour the paint into a dry, clean, colorless glass test tube with a diameter of 15mm,
and let it stand in the environment until the bubbles disappear; observe the color of the paint under the diffuse light of the day to see if it is transparent. 0 smear method, take two pieces of paint film samples before measuring electrical properties to observe the color, gloss, mechanical impurities and particles of the paint film.
Answer: Accurate number of turns and good insulation between turns.
Good insulation to ground. The size and shape of the coil meet the requirements.
The main insulation should have good wire embedding process performance.
Meet other special requirements, such as explosion-proof, moisture-proof and mildew-proof.
Answer: The arrangement forms include single winding, double-row winding, single-row winding, bow-shaped transposition, N-shaped transposition, brick-shaped arrangement, etc.
Answer: Usually there are the following types:
① Use winding wire insulation as inter-turn insulation.
② Gold film pads are used between turns.
③ The nose or the whole coil is wrapped with a layer of mica tape every other turn.
④ 1 to 2 layers of mica tape are wrapped per half turn.
⑤ The insulated tube is placed at the transposition of the bow-shaped transposition coil, and the insulation between the rows of the N-shaped transposition coil is placed, and the soft mica board is placed at the intersection of the wire turns and the nose.
Answer: The purpose of coil shaping is to make the shape and relevant dimensions of the coil meet the design requirements, and to make the end shape of the entire coil basically consistent. In order to reduce insulation damage, shaping is carried out after the inter-turn insulation wrapping and before the ground insulation wrapping.
Answer: Inter-turn glueing refers to hot pressing the turns of the wire in the straight part of the coil into a solid whole. Its function can make the cross-sectional dimensions of the coil meet the requirements, provide a guarantee for the thickness of the main insulation, and improve the stiffness of the coil, reducing the deformation of the coil during the manufacturing process.
Answer:
1.Accurate half-lapping.
Answer: One method of wrapping lead wire insulation is to wrap the lead wire insulation first, and then wrap the end insulation. The other method is to wrap the lead wire insulation during the process of wrapping the end main insulation.
Answer: Insulation overlap is when the slot insulation and end insulation of the ring-type stator coil are wrapped with two materials, the two materials should be overlapped at a certain position, that is, insulation overlap, which is divided into wrapping insulation overlap and wrapping insulation overlap.
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Time:11-05 2024
Time:10-29 2024
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