Electric Motor insulation is not simple, here I have summarized 50 key issues about electric motor insulation as follows;
What does electric motor insulation includ?
A: Electric Motor insulation includes inter-strand, inter-turn, inter-row, inter-layer and ground insulation of the coil, various insulation components used for end support or fixing, and insulation of connecting wires and lead wires.
What is the main insulation of the coil?
A: The main insulation of the coil refers to the insulation between the coil to the body and other windings, which is also called the insulation to the ground.
What is inter-turn insulation?
A: Turn-to-turn insulation refers to the insulation between turns of the same coil and turns.
What is the inter-strand insulation?
A: Inter-strand insulation refers to the insulation between the strands of the same turn, generally for the insulation of the winding electromagnetic wire itself.
What is inter-row insulation?
A: Inter-row insulation is the insulation of several rows of wires connected in parallel.
Why people regard the coil as the heart of the motor?
A: electtric Motor insulation structure is to play a role in electrical insulation, but some also play a mechanical support, fixed role in the long-term operation of the motor insulation by the role of electricity, heat, mechanical force and the impact of different environmental conditions, insulation will gradually aging, and eventually lose its proper performance. Therefore, the reliability and life of the motor is largely determined by the insulation of the coil, so people compare the coil to the heart of the electric motor.
What are the basic factors of insulation damage of commonly electric motor coils?
A: Commonly electric motor coil insulation damage to the basic factors are thermal, electrical, mechanical force and environmental conditions.
Electric motor winding insulation for which kinds of heat-resistant grade?
A: Electric Motor winding insulation can be divided into: B grade, F grade, H grade, C grade.
What are the main factors that determine the insulation structure of low-voltage electric motors?
A: The main is the slot shape. Insertion method. Insulation material and insulation treatment process.
Small and medium-sized electric motor stator slot shape depending on what? What slot shape is generally used in small low-voltage electric motors?
A: Small and medium-sized electric motor stator slot shape depends on the capacity and voltage and winding form, small low-voltage electric motors are generally used in the semi-closed slot.
What does high-voltage electric motor mean?
A: High-voltage electric motors generally refer to 3KV and above AC motors and generators.
High-voltage electric motor coil insulation structure of the coil stator to determine the main type of insulation?
A: Mainly to determine the inter-turn insulation. Slot insulation. End insulation and lead insulation.
The main insulation of high-voltage electric motor coil is usually composed of which three materials? What is the main improve for Main insulation ?
A: Main insulation is usually composed of mica, reinforcing material and adhesive, and the main insulation improvement mainly improves the heat resistance of the adhesive and electric motor performance.
What are the two structural forms of synchronous motor convex pole rotor coil?
A: The two structural forms of synchronous machine convex pole rotor coils are multi-layer multi-turn pole coils and single-layer multi-turn pole coils.
What are the types of synchronous machine hidden pole rotor coils?
A: Synchronous machine hidden pole rotor coil has continuous type. Half-turn type and single concentric type.
What are the two types of inlaid wire rotor windings? What kind of electric motor are they suitable for?
A: There are two types of winding: loose and inserted, the former is used for small motors and the latter is used for medium and large electric motors.
Insulating varnish can be divided into several categories according to the use?
A: Insulating varnish can be divided into impregnating varnish according to its use. Covering varnish. Guigang sheet varnish. Enameled wire enamels. Gluing varnish, etc.
Insulating impregnating varnish can be divided into which two categories? What are their advantages and disadvantages?
A: Insulating impregnating varnish can be divided into two types.
① solvent insulating impregnating varnish.
② solvent-free insulating impregnating varnish. The former has good permeability, long storage period, cheap.
Use and production management is convenient, but the paint has a long baking time when dipping workpiece curing slow, solvent evaporation caused by waste and environmental pollution and other shortcomings.
The latter has the advantages of fast curing, viscosity changes with temperature, small volatiles during curing, good insulation and dielectric properties, large amount of hanging paint, etc.,
But this paint has the disadvantages of expensive, short storage period, large viscosity, complex production management.
What are the basic principles for the selection of insulating impregnating paint?
A: ① Viscosity should be low, solid content should be high, easy to penetrate and fill the impregnation. The amount of hanging paint should be large.
② impregnating paint thick layer curing fast, good dryness, strong bonding, paint film is elastic, and can withstand the centrifugal force of the electric motor operation.
③Good electrical properties, heat resistance, moisture resistance, oil resistance and chemical stability.
④It is harmless to conductors and other insulating materials and has good compatibility.
⑤ Cheap, materials based on domestic, long storage period and small toxicity, etc.
What are the basic principles for the selection of insulation covering paint?
A: ①Fixed color, smooth, flat, bright and glossy paint film.
②Have a high degree of dispersion. The covering power should be strong.
③Long storage period, good stability, no gumming phenomenon.
④The paint film has enough hardness and wear resistance, good mechanical properties.
⑤The paint film has good arc resistance and dielectric properties.
⑥The paint film has good moisture-proof, oil-proof and chemical-proof, and for the insulating covering paint for the motor with temperature and heat should also have anti-toxicity and anti-salt spray.
(7) For the special anti-corona covering paint used for high-voltage motors, there is also good resistance stability, uniformity and a certain resistance value.
What are the two kinds of epoxy resins commonly used for coil insulation?
A: The commonly used epoxy resins are bisphenol A type and phenolic epoxy resin.
Which two types of epoxy resin curing agents can be classified according to the curing temperature?
A: Room temperature curing agent and heating curing agent.
What are the impregnated fiber products made of?
A: Fiber products made of insulating fiber products as the substrate, impregnated with insulating paint, such as lacquered cloth, lacquered tubes and tapes, etc.
What are the advantages and disadvantages of glass fiber? What methods are commonly used to improve its disadvantages?
A: The advantages of strong tension resistance, high heat resistance, moisture absorption is small. The disadvantages are: poor flexibility, not resistant to folding, often synthetic fibers to interweave or chemical treatment methods to improve its flexibility and adhesion of the paint film.
What kinds of glass lacquer cloth are commonly used for coil insulation?
A: Four kinds of glass cloth are commonly used for coil insulation, namely: 2430 asphalt alkyd glass cloth, 2432 alkyd glass lacquer cloth, 241 polyester glass lacquer cloth, 2450 silicone glass lacquer cloth.
What material is the insulating paint tube made of? What is its main role?
A: Insulating lacquer tube is made of natural fiber, synthetic fiber or alkali-free glass fiber woven into a tube, and then dipped in insulating lacquer or resin, after drying and made of a certain electromechanical properties and soft lacquer tube, mainly used for low-voltage coil or winding of the lead wire, inter-pole connection line insulation.
What are the commonly used lacquer tubes?
A: Commonly used lacquer tubes are 2751 silicone rubber edge glass lacquer tube (H level insulation) and 2750 silicone glass lacquer tube (H level insulation).
How are the laminated products made?
A: Laminated products are made of fiber products substrate, dipped or coated with different adhesives, made of fiber products, and then hot pressed or rolled into a laminated junction of insulating materials, mainly including laminate, tube (tube), rod and special profiles.
What is the basic media barrier of mica products?
A: It is mica.
What properties does mica have?
A: Mica has good insulation and dielectric properties, high heat resistance and chemical stability.
What are the three kinds of widely used powder mica paper according to their different preparation processes?
A: ① Cooked mica paper, it is the use of mica scrap, the production of powder mica paper by thermochemical methods.
② raw mica paper, it is the use of mica scrap, the application of high-pressure water crushing method of production of powder mica paper.
③Large scale mica paper, it is pure mica material, with high pressure water impact method to produce the scale of larger powder mica paper.
What are the advantages of powder mica paper compared with flake mica?
A: It has the following advantages.
①Improve the utilization rate of natural mica, from the original 7% - 10% can be increased to more than 80%.
②The thickness of powder mica paper is uniform, and the thickness of the products made is uniform, thus the electrical properties are stable and the thermal conductivity is good.
③It is conducive to mechanized production of powder mica products, which can improve the production efficiency, reduce the cost and improve the labor conditions.
What is the main composition of mica products?
A: Mainly composed of mica, adhesives and reinforcing materials?
There are many kinds of mica products, which categories can be classified according to their uses?
A: According to the purpose, they can be divided into four categories: mica tape, mica plate, mica box and mica glass.
What kinds of electrical films are commonly used for coil insulation? Briefly describe their common points? What are their uses?
A: The commonly used electrical films are: 6062 polyester film; 6065 polyester imide film and PTFE film. Their common points are thin thickness, soft, moisture-resistant, and have good electromechanical properties.
Uses: mainly used as coil winding insulation, low-voltage motor slot insulation, etc., while PTFE film is often used as the coil insulation hot pressing molding release material.
Briefly describe the composition and purpose of composite products?
A: Composite products are made of electrician's film with fiber materials bonded on one or both sides, the purpose is to enhance the mechanical properties of the film, improve the tear strength and surface stiffness to improve the use of process.
What kinds of composite products are commonly used?
A: Commonly used composite products are.
①6520 mylar film insulation paper composite foil.
②6530 polyester film glass lacquer cloth composite foil.
③Mylar film polyester fiber paper composite foil (DMD).
④Mylar film aromatic polyamide fiber paper laminated foil (NMN).
⑤Mylar film sulfonamide poly nonwoven laminated foil (SDMSD277)
⑥Polyimide film aromatic cluster polyamide fiber paper composite foil (NHN)
Insulation material inspection project according to its performance can be divided into which four aspects?
A: According to its performance can be divided into electrical, mechanical, physical and chemical and thermal properties of the four aspects.
What are the main contents of the electrical properties of the insulating materials?
A: Mainly: breakdown strength, volume resistivity, surface resistivity, relative dielectric constant Lou, dielectric loss angle tangent and corona resistance and other items.
Write out the composition of mica products to determine the content of the three basic formula? And mark the meaning of the letters in each category?
A: 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 - the weight of the specimen before drying (g)
G1 - specimen weight after drying (g)
G2 - specimen weight after scorching (g)
K - glass cloth standard weight (g/m²)
F - specimen area (m²)
D - the number of reinforcing layers.
Briefly describe the two appearance inspection methods of insulating paint?
A:Test tube method:Pour the paint into a dry, clean, colorless glass test tube of 15mm in diameter.
The test tube method: the paint is poured into a 15mm diameter dry, clean, colorless glass test tube and left to stand in the environment until the bubbles disappear; the color of the paint is observed in daylight under diffused light, whether it is transparent or not. 0 smear method, two pieces of paint film specimens are taken before the determination of electrical properties to observe the color of the paint film, gloss, the presence of mechanical impurities and particles, etc.
What are the basic technical requirements of high-voltage elelctric motor coil stator?
A: Accurate number of turns, good insulation between turns.
Good insulation to ground. The size and shape of the coil meets the requirements.
The main insulation should have good performance of the embedded wire process.
Meet other special requirements, such as explosion-proof, moisture-proof and mold-proof.
What are the forms of wire turn arrangement of common coil type high-voltage stator coils?
A: The arrangement form has single winding, double rows of several roots and winding, single rows of several roots and winding, bow transposition, N-shaped transposition, brick-shaped arrangement, etc.
What are the types of inter-turn structure of high-voltage stator coils?
A: There are usually the following types:
① with winding line insulation as inter-turn insulation.
② inter-turn pad gold film pad strip.
③Nose or full coil inter-turn half-stacked with a layer of mica tape.
④1 to 2 layers of mica tape per turn and a half stack.
⑤ Bow shaped transposition coil transposition at the set of insulating tube, N-shaped transposition coil package inter-row insulation, wire turns and the intersection of the nose pad soft mica plate.
Why should the coil be shaped? When shaping?
A: Coil shaping is to make the shape and size of the coil to meet the design requirements, and make the end of the whole coil shape is basically the same. To reduce insulation damage, shaping in the inter-turn insulation wrapping and ground insulation wrapping before.
What does inter-turn gluing mean? What is the function?
A: Inter-turn gluing refers to the hot pressing of each turn of wire in the straight part of the coil into a solid whole, which can make the cross-sectional size of the coil meet the requirements and provide a guarantee for the thickness of the main insulation, and can improve the stiffness of the coil and reduce the deformation of the coil in the manufacturing process.
What are the basic requirements of insulation tape wrapping?
A:1.Half stacked package is accurate.2.The layers are flat and fold-free.3.The band tension is appropriate.4.The wrapping direction is the same.5.The number of layers meets the requirements.
What are the two methods of lead insulation?
A: One is to wrap the lead insulation first, and then wrap the end insulation, and the other is to wrap the lead insulation in the process of wrapping the end main insulation.
What is insulation lap? Several lap methods?
A, insulation lap is the slot insulation and end insulation of the coil stator coil with two materials wrapped, the two materials should be in a certain position on the lap that insulation lap, divided into two types of coil insulation lap and winding insulation lap.
