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Introduction to several kinds of insulating paints

Insulation paint is a special kind of paint
Insulating paint, also called insulating coating, is a coating with excellent electrical insulation.It has good electrochemical properties, thermal properties, mechanical properties and chemical properties. Mostly inslulating paint is varnish, also colored paint.Insulating paint is a kind of special paint.Insulating paint is an important insulating material which is based on high polymer and can be cured into insulating film or insulating whole under certain conditions.The insulating paint is composed of base material, flame retardant, curing agent, color filler, solvent and so on.

Classification and application of insulating paint
1.Impregnating paint.Impregnating paint is divided into two categories: solvent paint and solvent-free paint, mainly used for impregnating the coils of motors and electrical appliances to fill their gaps and micro-holes, and after curing, it can form a continuous flat film on the surface of the impregnated object, and make it bond into a hard whole.
2.Enameled wire paint.Enameled wire paint is mainly used for enameled wire insulation.Due to the wire in the process of winding coils, wire inserting, etc, will be affected by the thermal, chemical, and a variety of mechanical force, so the wire coating should have feartures below: good coating (i.e., can be evenly coated), coating adhesion, surface smooth, soft with toughness, certain abrasion resistance and flexibility, good electric performance, heat resistance, solvent resistance, no corrosion to the copper conductor.
3.Coat paint.Coat paint is used to coat impregnated coils and insulating parts, forming an insulating protective layer of uniform thickness on the surface to prevent the primitive insulation from mechanical damage and erosion of atmosphere and chemicals, and improve the surface insulation strength. Therefore, the requirements of the coating paint are: fast drying, strong adhesion, hard film, high mechanical strength, moisture resistance, oil resistance, corrosion resistance and other characteristics. Coating paints are divided into alkyd, epoxy and silicone paints according to the type of resin.Epoxy paint has better moisture resistance, mildew resistance, internal dryness and adhesion than alkyd paint, with high hardness. It is widely used for the surface coating of electric machinery and electrical equipment parts in hot and humid areas.Silicone paint has high heat resistance and can be used as a coating paint for class H electrical machines.
4.Silicon steel sheet paint.Silicon steel sheet paint is used to coat silicon steel sheet to reduce the eddy current loss of the core and enhance the corrosion resistance.High temperature and short time drying are required after coating.It is characterized by thin layers, strong adhesion, hard, smooth, uniform thickness, oil resistance, moisture resistance, good electrical performance.
5.Anti-corona paint.Corona discharge is a kind of discharge phenomenon in extremely uneven electric field, in which the air ionizes at the strong point (such as the sharp point of the electrode) and produces blue halo.Anti-corona paint is generally composed of insulating varnish and non-metallic conductor (carbon black, graphite, etc.) powder mixture, mainly used for high voltage coil , such as for  coil end of large high-voltage motor in the higher voltage.In industry, it requires the anti-corona paint with surface resistivity stability, strong adhesion, good wear resistance, fast drying, storage resistance. And anti-corona paint can be painted on the coil surface alone, can also be coated in asbestos belt, glass belt, wrapped in the coil outer layer, or coated on the glass cloth and the main insulation molding.

What is the purpose of motor winding varnishing besides insulation?
Winding dipping painting is an important and key process in motor manufacturing.The heat resistance and thermal conductivity of winding insulation can be improved by dipping paint.The insulation gap of the windings before dip painting is filled with air and poor thermal conductivity.After dipping, the insulating paint fills all the gaps of the insulation of the windings, greatly enhancing the thermal conductivity.After the formation of paint film, can reduce the contact with air, play a role in delaying oxidation and improving heat resistance.
The electrical properties of winding insulation can also be improved by dip painting.After dipping paint, the gap between winding turns, phase and insulating layer and inside insulating material is filled with insulating paint, which basically eliminates bubbles and forms solid insulation with strong pressure resistance, thus improving the electrical performance of winding insulation.
It can also improve the moisture resistance and chemical stability of the winding insulation.The winding insulation treated by special dip paint also has the ability of dew proof, corona proof, anticorrosion and oil proof.
Dip paint can also improve the mechanical strength of the winding.After being dipped in paint, the wires of the windings are bonded into a solid whole, thus strengthening the mechanical strength of the windings and reducing the insulation looseness and wear caused by electromagnetic force, vibration and thermal expansion and cold contraction.

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