Low thermal conductivity 3. A wide range of colours 5. Low electrical conductivity. Plastics, most commonly, are classified as 1. Thermoplastic and 2 Thermosetting. Thermoplastic materials are those which soften on the application of heat, with or without pressure but they require cooling to set them to shape.
Thermosetting materials are those plastics which require heat and pressure to mould them into shape. Thermoplastic Materials: Polyethylene or Polythene : Polythenes are obtainable as viscous liquids, gums and tough flexible solids suitable for moulding. They have waxlike in appearance, semi-transparent, odourless and one of the lightest plastics. Flexible over a wide temperature range. High resistivity and dielectric strength.
Chemically resistant. Do not absorb moisture. Dielectric losses and dielectric constant are low. They are relatively cheaper in cost. Polyvinyl chloride PVC : The vinyl chlorides are formed from hydrochloric acid, limestone, and natural gas or coal. The forms of vinyl chloride are almost unlimited. PVC is used in electric and electronic equipment such as circuit boards, cables, electrical boxes, computer housing, insulation and adhesive tapes.
The flexible types are strong, tear resistant and have good ageing properties. The rigid types have good dimensional stability and are water resistant. They are resistant to acids and alkalies. It becomes soft beyond C. It is self extinguishing when ignited and the source of flame is removed. It offers more resistance to oxygen, ozone and sunlight. Softening temperature Insulation resistance For example PVC is difficult to ignite and in the absence of a powerful external flame will not 8.
This is due to its chlorine compound. This makes it an ideal construction and cable material. The incineration burning of PVC causes the release of toxic chemicals like dioxins and other chemicals that are harmful to humans. Thermosetting Plastics Aminos [a] Urea formaldehyde resins : They are derived from the reaction of urea with formal dehyde or its polymers. These resins cannot offer high resistance to heat.
It is highly resistant to chemicals. Possess outstanding electric arc resistance. Excellent resistance to water. Available in full range of transluscent or opaque colours. Boards are made from these material are used as distributor heads, casings for electric devices, terminal boards. Phenolics [Phenol formaldehyde resin]: They are made by a reaction between phenol and formaldehyde.
They are probably the most widely used and cheapest of thermosetting plastics. Strong, rigid and dimensionally stable. Heat and solvent resistant.
Non-conductors of electricity. Used as Electrical appliance handles, TV and Radio cabinets 1. Varnishes, of different types are used in the insulation system of electrical machines for impregnation and finishing applications. Advantages of these coatings are: Increased mechanical bonding to the winding wires Improved dielectric properties Improved thermal conductivity Protection to the winding against moisture and chemically corrosive environment.
Varnishes are classified based on: 1. Applications of varnish. Type of varnish curing method. Based on main raw material used in varnish. Insulating varnish based on applications: 1. Impregnating varnish 2. Finishing varnishes 4. Bonding varnishes 5. Special purpose varnishes. Insulating varnish based onCuring method : 1. Air drying type 2. The above varnishes come in Solvent based and Solvent-less based. Impregnating varnish: The main function of impregnating varnish is not electrical insulation of current-carrying conductors.
The filling of empty spaces not only gives mechanical strength, but also hinders or prevents penetration of unwanted substances from the environment. This gives the component improved resistance to chemical attack, to moisture, thus extending its service life.
They are applied by dipping the component in the varnish, or less often by trickling process. These type of varnishes needs to be cured heated in a oven at temperatures ranging from oc to oc for 2 to 12 hours time. Finishing coating varnish : Finishing varnishe is used not to strengthen the windings, but to protect the component from external attack by environment conditions.
They are applied purely as a surface coating, and are characterised by outstanding film forming properties. Often applied by paint brush or sprayed, in repair shops after rewinding works. They are mostly air drying type. It takes almost a day to completely cure. Core plate varnish : This varnish is applied to electrical laminations used in electrical machines. This acts as insulating layer between successive laminations. It is baked at high temperatures, oo c for about 5 min.
Binder varnish : This type of varnish is used as bonding agent between two insulating materials. Mechanically weak materials when bonded show good rigidity. It is baked at temperatures of about oc to oc for a duration of 3min. Properties of Insulating varnish coating after curing : Varnish after application and after under going required curing process at appropriate temperature forms into a uniform film on the materials. The elastic varnish film has very good mechanical properties such as hardness, flexibility, penetration, good adhesion and Bonding strength.
It has good dielectric behaviour and dielectric strength. Applying Varnishes: For treating coils, windings, and insulating parts with insulating varnishes the methods generally used are Vacuum impregnation, Hot dipping. Finishing varnishes are usually applied by brush or spray. Mica sticking varnishes are applied by brush or sometimes by machine[ by passing a roller which dips in the varnish].
Synthetic varnishes are frequently used for impregnation by dipping and require baking to develop their properties fully. Clear baking varnishArmatures, field coils and instruments. Black baking varnishes Armatures, field coils and transformers when higher electric strength and resistance to moisture, acids, and alkalies are wanted. They have less resistance than those of clear. Sticking varnish.
Cementing cloth, paper, mica etc. Core-plate varnish[air drying, baking and flashing].. Insulating armature and transformer laminations. The air drying is not suitable for oil-immersed operation. Epoxy resin varnish [baking]..
All coil impregnation, internal curing, where superior durability and chemical and moisture resistance are required. Silicone resin varnish [air drying and baking].. Motor stators and rotors, transformers, coils, for high temperatures and high-humidity service.
Polyester resin varnishes [baking]Motor stators and rotors, transformers, coils, for high temperature service not so severe as to require silicones. Phenolic varnishes [baking ]. Hermetic motor coils and bonding of form wound coils. Table 1. Epoxy varnished glass tape on coil ends and alkyd bonded mica glass sheet between layers No extra insulation because the phase-tophase insulation itself is sufficient Bakalized fabric strip Epoxy fibreglass strip.
A Mica tape B rubber tape C cotton tape D Plastic tape Which one of the following is used as slot liner in an electric motor? A silk tape B Micanite tape C Film paper wood as sticks is used as in an electric motor.
The electrical devices coated with varnish should be heated at about o c for 3 5 hours to attain good insulating property. Part - B Answer the following questions in one or two words 1. What property should be more for the insulating material to be thinner?
Which classes of insulating material can withstand temp. In motor winding applications, where film paper is used? What is the name of the MICA splitting bonded to electrical grade paper? Which is called as secondary insulation in a motor? Give two examples of Thermoplastic material? Give two examples of Thermosetting plastic material? Which type of rubber can maintain its properties even at low temperature eg.
Part - C Answer the following question briefly 1. What are the areas in which insulating materials are used? List the classes in which insulating materials are classified based on Temperature? Give two examples of insulating materials in each of the above classes. List four important characteristics of a good insulating material. List some of the insulation materials in which sleeves are made? Discuss about the properties of any four insulating materials used in coil winding of Electric motors.
What are differences between Thermoplastic and thermosetting plastics? Discuss the properties of any two materials from each category. It is used for the winding of electric motors, transformers, inductors, generators, speaker coils, etc. A wire is a single, usually cylindrical or rectangular cross-section, length of metal. Wires are used to carry electricity and telecommunications signals. Wire is generally formed by drawing the metal through a hole in a die or draw plate.
Standard sizes are determined by various wire gauges. The term wire is also used more loosely to refer to a bundle of such strands, as in multistranded wire, which is more correctly termed a wire rope in mechanics, or a cable in electricity. The metals must in the first place be ductile and strong in tension, the quality on which the utility of wire principally depends.
The metals suitable for wire, possessing almost equal ductility, are platinum, silver, iron, copper, aluminium and gold; and it is only from these and certain of their alloys with other metals, principally brass and bronze, that wire is prepared.
By careful treatment extremely thin wire can be produced. Copper wires could be plated with other metals, such as tin, nickel, and silver to handle different temperatures, provide lubrication, provide easier stripping of rubber from copper. Wire used to carry electricity is made up of materials having very low resistivity such as pure copper or aluminium. Mechanical Properties: 1 Good Ductivity: It is that property of a material which allows it to be drawn into a wire.
Economical Factors: 1 Low cost 2 Easily available 3 Easy to manufacture. Characteristics of a Good Conductor Material: The conductor materials should have low resistivity so that any amount of power can be transmitted without much loss in the conductor.
Copper is very widely used in wires, cables, windings of generators and transformers, overhead conductors, busbars. It is obtained by drawing cold copper bars into conductor length. It is used for overhead line conductors and busbars.
It can be easily shaped into any form. Low-resistivity Hard Copper is used in power cables, windings, and coils as an insulated conductor. It has high flexibility and high conductivity. Aluminium : 1 Pure aluminium has silvery colour and polish. It offers high resistance to corrosion. Aluminium is most often used as overhead transmission conductors, busbars, ACRS conductors. Well suited for cold climate. Metal is costly per cent conductivity Good resistance to corrosion Heavier as compared to aluminium Good ductility and malleability Excellent soldering and welding capacity Less suited for low temperature Aluminium Metal is cheap 75 per cent conductivity Good resistance to corrosion Lighter as compared to copper Good ductility and malleability Poor solderability and weldability Well suited to cold climate.
Very small cross-section can carry heavy Cross-section should be 50 percent current more to carry the same current as that of copper. Because of softness and flexibility, it can easily be twisted repeatedly.
Due to brittleness, cannot be twisted. The wind pressure and weight of snow is The wind pressure and weight of snow is less because of smaller cross-section.
The core material wire is copper or aluminum, coated with a thin layer of a polyurethane, polyamide, or polyester resin - called as enamel. The thin layer of insulation coated on Enamelled wire, prevents the wire surfaces from being in a short circuit when wound into coils.
It is used mainly in the construction of motors, electromagnets, transformers and inductors. For ease of manufacturing inductive components like transformers and inductors, most new enamelled wire has enamel that acts as a flux when burnt during soldering.
This means that the electrical connections at the ends can be made without stripping off the insulation first. Older enamelled copper wires normally require sandpapering or scraping to remove the insulation before soldering.
Enamelled wires are classified by their diameter as SWG number or area square millimetres , temperature class and insulation class. Enameled wires are manufactured in both round and rectangular shapes. Rectangular wire is used in larger machine windings to make the most efficient use of available winding space. Breakdown voltage depends on the thickness of the covering, which can be of 3 types: Grade 1, Grade 2 and Grade 3.
Higher grades have thicker insulation and thus higher breakdown voltages. The temperature class indicates the temperature of the wire at which it can have a 20, hour service life. At lower temperatures the service life of the wire is longer about a factor 2 for every 10 C lower temperature. Common temperature classes are , and C. Table 2. Standard Wire Gauge S. Area mm2 Area mm2 0. Solderable polyurethane enamelled round copper wire. It has thermal capacity of C, C and C. The diameter ranges from 0.
Polymide-imide enamelled round copper wire, Class Paper Covered Rectangular Copper Wire Polyesterimide enamelled rectangular copper wire. It has Thermal Capacity of C. This type of enamel wire are used in High Power Motors. With thermal capacity of C and diameter range from 0.
Glass-fibre Wound, Polyester or Polyesterimide Varnish-treated, Bare or enamelled rectangular copper wire, temperature index Glass-fibre wound, polyester or polyesterimide varnish-treated, bare or enamelled rectangular copper wire, temperature index Glass-fibre wound, silicone varnish treated bare or enamelled rectangular copper wire, temperature index Glass-fibre braided, polyester or polyesterimide varnish-treated, bare or enamelled rectangular copper wire, temperature index Aromatic polymide tape wrapped round copper wires, Class Aromatic polyimide tape wrapped rectangular Copper wire, Class Very low dissipation factor, remaining reasonably constant at high frequencies or under humid conditions.
No mechanical or chemical stripping required. Adequate ventilation required when tinning or soldering. Thermoplastic flow temperature not less than C, Smooth Glossy surface finish, Chemically very stable, resists extraction with R22, methanol trichloroethylene and perchlorethylene. Usable in hermetically sealed coils Excellent stability with a heat shock of not less than C. Good resistance to abrasion.
Good flexibility and adhesion to the conductor Smaller coefficient of friction, Higher mechanical intensity, Excellent heat resistance. Good solderability. Limitations : Insulation properties downgraded over C.
Prone to hydrolysis if used in hermetic systems or encapsulations when in the presence of cellulosic materials or moisture. Prolonged contact with aggressive solvents e. Round Wires: It has thin and thick conductors and are used in semi-closed slot type motors and mush winding rotors. It is wounded in reels and available in Kilograms. Rectangular straps: It is used in open type slot motors. These conductors are available as long straps in meters.
They are used in the following places. Stranded wires: Stranded wire is composed of a bundle of small-gauge wires to make a larger conductor. Stranded wire is more flexible than solid wire of the same total cross-sectional area.
Stranded wire is used whenever ease of bending or repeated bending are required. Such situations include connections between circuit boards in printed-circuit-board devices, where the rigidity of solid wire would produce too much stress as a result of movement during assembly or servicing; A.
Note: Usage of alternate sizes 1. If rewinding is done, use the existing winding wire gauge number for the new winding. Sometimes if same gauge winding wire is not available then we can use the 2 runs of wire each having half of the area of cross section of the original one.
Standard Gauge Number 10 12 14 17 2. Area of Cross-section of one particular wire gauge number is two times more than that of gauge number, when increased by three. For example area of cross-section for 17 gauge wire is approximately two times more than that of 20 gauge wires. If 17 gauge wire is not available then we use two 20 gauge wires. When 20 gauge and 17 gauge wires are used for particular length, then the weight of 17 gauge wire is double as that of the weight of the 20 gauge wire, because weight is directly proportional to the area of cross-section of the wire.
Resistance of the winding wire is indirectly proportional to the cross-sectional area of the wire. Therefore, the resistance of 17 gauge wire is half of the resistance value of 20 gauge wire. Resistance of winding is measured in two methods. Then current in each phase is measured and then the resistance of the winding is calculated. Each notch is stamped with a number, and the wire which just fits a given notch, is stated to be of, say, No. Oblong plates are similarly notched.
Many gauges are made with a wedge-like slot into which the wire is thrust; one edge being graduated, the point at which the movement of the wire is arrested gives its size. The graduations are those of standard wire, or in thousandths of an inch. In some cases both edges are graduated differently to serve for comparison between two systems of measurement. A few gauges are made with holes into which the wire has to be thrust.
All gauges are hardened and ground to dimensions. In some applications wire sizes are specified as the cross sectional area of the wire, usually in mm. Advantages of this system include the ability to readily calculate the physical dimensions or weight of wire, ability to take account of non-circular wire, and ease of calculation of electrical properties.
This determines the amount of electric current a wire can safely carry, as well as its electrical resistance and weight per unit of length. Wire gauge is applicable to both electrical and non-electrical wires, mostly used in electrical wiring.
The basis being the mil. Between these, the diameter, or thickness, decreases by The mil denotes one thousandth part of an inch more commonly denoted as thou. The circular mil is the equivalent area of a circle whose diameter is 0.
This can also be expressed as the diameter in thousandths of an inch raised to the power 2 and may or may not be rounded to the nearest ten. The circular mil is an old unit of cross sectional area, used for denoting the cross-sectional size of an electrical conductor or cable. To transfer power without much loss of power, the conductor material should be A Very light C have very low resistance B very strong D have very low weight.
Enameled wire has very thin coating of varnish over copper or aluminium wire. This thin layer of coating acts as A protective coating against rusting C protective coating of insulation B protective coating against heat D coating to give good appearance. Enamel covering on the conductor wires cannot withstand for long the effects of A current B voltage C moisture D certain solvents.
Which property allows the material to be drawn into thin wires? Which type of copper conductor is called hard copper? Where aluminmum conductors are widely used? Which one has higher resistivity for the given length.
Copper or Aluminium? What is the expected service life in hours of the wire for the given temperature class? Enamelled wires should not be used beyond this temperature.
What it is? If during rewinding same gauge winding wire is not available then we can use several runs of lesser gauge wire in place of previous one. Which parameter should be same in both the cases? What is the equivalent size in mm for 1 mil?
What is meant by conductor? In which type of motors rectangle conductors are used? What is meant by flexible wire? What are the three types of enamel thickness? Part - D Answer the following question in one page level 1. What are the advantages of using copper as winding wire? What are the properties needed for winding wire? Explain the method to find the winding wire gauge number with the gauge plate.
State any ten properties of Enamel coating of the wires. The coils used in windings are shown in Fig. Each coil has active and inactive sides. A coil can in general have any number of turns. Similarly, a two turn coil has four conductors and a three turn coil has 6 conductors. Active side of a coil : It is the part of a coil which lies in the slots under a magnetic poleand emf is induced in this part only. In Fig. For a double layer winding, one half portion of the coil drawn with solid line corresponds to the coil side lying on the top of a slot, and the dotted line corresponds to the coil side lying in the bottom layer of another slot.
This type of representation is used for double layer winding. For a single layer winding, the complete coil is represented by a solid line.
Inactive side of a coil : The inactive side of a coil consists of two portions, namely the front end side and the back end side. The portions which are used to connect other coils are called front end side. These ends have two leads called as Coil Groups : One or more coils connected in series are called coil groups, as shown in Fig.
The number of coil groups is equal to the number of poles. For AC winding, the total number of coil groups depends upon the number of poles and the number of phases. Example 3. Solution From equation 3. Pole Pitch : It is the distance between the centres of two adjacent opposite poles. It is measured in terms of slots. It is expressed in terms of number of slots per pole or electrical degrees. Full pitch coil : A coil having a coil span equal to ed is called a full pitch coil, as shown in Fig.
Short pitch coil : A coil having a coil span less than ed by an angle , is called a short pitch coil, or fractional pitch coil, as shown in Fig. It is also called a chorded coil. Pitch Factor or coil span factor or chording factor, KP: When the two sides of the same coil are short pitched by an angle , as shown in Fig.
Due to phase angle difference, the actual emf is reduced by a factor cos and is called pitch factor or coil span factor or chording factor. Solution: From Fig. From equation 3. Distribution Factor, Kd : It is defined as the ratio of phasor addition of emfs induced in all the coils distributed in m slots under one pole region to their arithmetic addition of emfs induced in all the coils distributed in m slots under one pole region.
Winding Factor, KW : It is defined as the product of pitch factor and distribution factor. Solution : From equation 3. Taking point A as reference, ie. In between points A and C, points B and D are marked as and respectively. Point A is also marked as , as it is the same point as the reference point, reached after going around circle once.
Electrical degree, qed is used for accounting the angle between two points in rotating electrical machines. Since all electrical machines operate with the help of magnetic fields, the electrical degree is used with reference to the polarity of the magnetic field. Consider a two pole machine, as shown in Fig. Point A is exactly under the North pole field and is selected as reference point with Point C is under the South pole and magnetically opposite to North pole.
It is marked as ed or e. After one encircling, point A is reached and marked as ed or e. Consider a 4 pole machine, as shown in Fig. Point A is under North pole N1 and marked as Moving clockwise, point B is situated at md from point A.
But point B is under South pole S1, which is magnetically opposite to N1. Hence, point B is marked as Now, point C is under N2, which is md away from point A. Point C has the same magnetic polarity as that of point A, hence it is marked as Point D under S2 is md from point A, and hence marked as , ie.
After one complete encircling, point A is reached again, and marked as , ie. The mechanical and electrical degrees defer one another from the point of reference. Thus, mechanical and electrical degrees are related by the number of poles, P. Solution: From equation 3. Solution : S 6 P 6 From equation 3. Numbering the coil sides in slots: For convenience in laying out the windings, for double layer windings, the coil sides forming the top layers in the slot are given odd numbers and those forming the bottom layers are given even numbers.
The scheme of numbering the coil sides for two different double layer windings in slots are shown in Fig. For single layer winding, coil sides are numbered as shown in Fig. The slots used in the stator of induction motors, may be completely open or semiclosed as shown in Fig. The types of rotor slots used for squirrel cage induction rotor may be either closed or semiclosed types as shown in Fig.
The slots used in the armature of dc machines, may be completely open or semi-closed as shown in Fig. The type of slot insulation will vary according to the capacity of the machine. Slot Liner : The slot liner is an insulation sheet cut to the inner dimensions of the slots and projected on either side of the slots. In some applications, the edges of the slot liner are folded on either end to prevent them from sliding in the slots, as shown in Fig.
Coil Separator : When multilayer windings are used, to insulate the winding layers from each other, coil separators are used, as shown in Fig. They should be extended on either side of the slot. Packing Strip : The thick insulation paper used in between the slot liner and wedge is called a packing strip, as shown in Fig. This should extend beyond each end of the armature core. Wedge : It is a solid insulation piece like bamboo or fibre used to prevent the conductors from coming out of the slots.
It should be tightly held in the slots, as shown in Fig. Field Coil Formation : Field coils are wound with insulated copper wire whose diameter and number of turns depend on the exciting voltage and machine capacity. The wire can be wound on a wooden former that consists of the inner dimensions of the coil. The coils are wound over the former with the help of the coil winding machine. All coils are wound identically. The number of turns depends on the voltage rating of the machine where as the conductor size depends on the current rating.
For development of dc armature windings, few pitches related to the types of dc armature windings are Back pitch, Front pitch and Winding pitch. Back Pitch, Yb : It is the distance between the two active sides of the same coil under adjacent opposite poles.
For double layer winding, 3. Front Pitch, Yf : It is the distance between two coil sides connected to the same commutator segment. It should be an odd integer. Winding Pitch or Coil Pitch, Y : It is the distance between starting ends of two consecutive coils expressed in terms of coil sides. For a double layer winding, winding pitch should be an even integer. From Fig. In this type of winding, as shown in Fig. It is not, however, strictly a double layer winding, as the coil sides are places side by side and not one above the other.
Not Helpful 0 Helpful 3. Include your email address to get a message when this question is answered. By using this service, some information may be shared with YouTube.
Helpful 2 Not Helpful 0. If possible, practice on an old or inexpensive motor before you attempt to rewind an expensive one. Helpful 2 Not Helpful 2. Taking your motor to a repair shop to have it worked on by a qualified pro is much cheaper than being forced to replace the entire thing as a result of rewinding it incorrectly yourself.
Helpful 1 Not Helpful 1. Take some time to brush up on how electric motors work before you begin removing anything. Only magnet wire should be used to rewind a motor. No other type will be able to channel the electromagnetic energy needed to turn the motor. Using the wrong kind of wire could even lead to electrocution.
Helpful 1 Not Helpful 0. Always use the same gauge wire that was used originally. You Might Also Like How to. How to. Expert Interview. More References 7. About This Article. Co-authored by:. Co-authors: Updated: May 6, Categories: Motors Generators and Transformers. Article Summary X To rewind an electric motor, remove the motor's outer housing and use your hands to pull the armature out of the stator.
Thanks to all authors for creating a page that has been read , times. I couldn't find any info to do it, so I took it apart and had to do it twice, first time it burnt up. I don't know why, but I think I used the same amount of wire for both speeds, second time I did less for 2nd speed and used two different color wires to know which one is which, and after the second time the fan has been working properly.
More reader stories Hide reader stories. Did this article help you? Cookies make wikiHow better. By continuing to use our site, you agree to our cookie policy. Jose Huerta Sep 3, John Sherrer Jun 27, Also the amount of wire to be exact when winding it back to the stator really is important, that's why I had measured it after I removed it, thanks for the heads up. Patrick Chinedum Dec 5, It inspires confidence, thanks. Shawn K. Jan 6, But you'd better know what you're getting into!
Kevin Kipruto May 13, Share yours! More success stories Hide success stories. Featured Articles How to. Trending Articles How to. Third time i successful rewind motor. Because gap between stator and cover was very small, i decided to do a little bit bigger first coils, and a little bit smaller last coils.
You can se that on measurment of resistance where, winding resistances aren't identical. But in next measurement we can see that resistances do not dramatically affect on electric motors performance.
I made all tests with two different voltages. Motor was made for voltage V, but now we have V in EU. In upper table there is data from manufacturer in first line. In second line is measurement at V and third line at V. If we compare all data we can see that motor isn't bad at all. All parameters are very close together. I hope you enjoined my presentation of rewinding a three phase motor. If you have any questions please ask, and i will try to answer ass soon as possible. Thank you for your attention.
Question 1 year ago on Step Answer 5 months ago. Answer 7 months ago. Answer 1 year ago. I want 24 slot 2Pol 3 phase 1 kilowatt motor winding diagram, and 48 slot ,3 phase motor diagram and motor winding model, connection diagram please give me. Question 1 year ago. Question 1 year ago on Introduction. Reply 1 year ago. Working as an industrial electrician this is counter productive vs purchasing a new one. However, some fantastic learning to be gained from this. I plan on having our apprentice look through this and also work through the calculations.
Fantastic detail. Thanks for the time commitment and also for a great intructable! Reply 3 years ago. I was curious about what the economics were for rebuilding such motors Could somebody make a living rebuilding these? I see several videos of people in India doing it, so I guess at least there it's a business. It's amazing the amount of effort and detail work that goes into it.
It seems like it wouldn't be worth it but I guess it must be at least marginally cheaper than building from scratch. Typically we will only rewind over 10hp. But yes there are companies out there that specialise in motor testing and rewinding. Please sir,single phase motor rewinding formula pdf send to gmail adress- pyithein gmail.
Introduction: Rewinding 3 Phase Motor. More by the author:. If you have any questions you can easily message me. I got this motor at my university. Motors Inscription board On the motors inscription board we can find most useful information about motor: Motors nominal voltage for star Y and triangle D motor connection [V] Motors nominal current for star Y and triangle D motor connection [A] Power of the electric motor [W] Power factor cos Fi Rotation speed [rpm] Nominal frequency [Hz].
Open the cover of conduit box. You can detect burned motors winding by unique smell smells like burned lacquer. Remove rotor from stator. You can gently hit rotors axis with rubber hammer.
Remove clamp, and safety ring if you have one. Then remove second cover. Do same on both sides of stator. Heat up winding with flame torch to burn out the rest of lacquer. If you burned old lacquer you should be able to push remain winding out of stators gaps.
Now measure dimensions of stators slot. If you have other shape of slot you look at upper picture. I copied this picture from book [Neven Srb; Elektromotori]. Pole step is distance on inner circle of stator, and it marks size of each pole. Stators yoke is part of stators package which extends from stators tooth to end of package. I picked 0,8mm wire. Mark ends of coils! Put motor in it. When motor heats up, spills lacquer on motors coils as you see on pictures 3.
Turn motor around and do the same 4. You can reuse old lacquer. Put motor in hot oven, and cook it for about 4 hours 6. Take motor out and clean edge so cover will fit perfectly. Put rotor in stator, and close it with second cover.
Screw motor together. Connect end of coils to clips, according to picture from analyse motor.
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