ELECTRICAL INSULATION COATINGS
Primary Insulation coating
Electrical devices such as motors, generators, and transformers function on the basis of electromagnetic induction. The rotational or linear movement of such electrical rotary equipment is caused by electromagnetic fields, generated by electrical coils, and their mutual repulsion forces. The wire enamel is applied to the metal wire concentrically in several coating operations in a thermal coating process, so-called enamelling process. The wire enamel is a varnish and consists of organic components (prepolymers) that react to cross-linked polymers during the baking and thus form an impermeable electrical insulation layer.
The best stability under all operating conditions is achieved by electrical rotary equipment (motors and generators) and static electrical equipment (transformers and sensors) if all the air trapped inside the wire windings is replaced with insulation material. This stage of the value-added chain is known as impregnation or secondary insulation. This normally thermal impregnating process, i.e. chemical process under the action of heat, also increases the mechanical stability of the electrical winding and protects the enameled wire during operation from environmental influences such as moisture. This impregnation can entail a trickling of the wire winding, a dip or dip-and-roll process. Today impregnation is increasingly carried out by means of the vacuum method in order to completely eliminate any air that might be trapped (VPI process). Trapped air bubbles reduce heat dissipation, since air is a good heat insulator, or they give rise to disruptive electrical charges in high-voltage applications, which can destroy the insulation. In addition, UV light curing might be employed, which creates very highly cross-linked, and thus impermeable, impregnating layers. The impregnating resin or varnish (impregnating material generally) consists of organic components (prepolymers) that react to cross-linked polymers during the curing process and thus form a further electrical insulation layer additional to the wire enamel.
The following different impregnating resins exist
Unsaturated polyester resins (UPs) with styrene or vinyl toluene as a reactive thinner UPs without volatile organic substances (Monomer free so-called MF resins) Epoxy resins Water-based resins Alkyd resins with an organic solvent or water-based.Where transformers for electrical power transmission are concerned, either impregnating resins (dry transformers) or insulation fluids (wet transformers) are used.
Electronic & Engineering Materials
The primary and secondary insulation completes the basic insulation of electrical equipment. For a range of electrical equipments as sensors, instrument transformers, induction systems, and printed wiring boards, additional properties are desired such as improved heat dissipation, much greater mechanical stability at high vibrational forces, noise reduction, and often the complete exclusion of environmental influences.
These properties are obtained by embedding or completely encapsulating or coating with an insulating material – in blends with other materials also called compound. Depending on whether – in what is usually a thermally based casting process, i.e. a chemical process under the action of heat – the mold is removed after casting or becomes a permanent element of the cast part, the process is referred to as casting insulation or potting insulation respectively.
In many cases the casting process is carried out under a vacuum to prevent air pockets. Trapped air bubbles reduce heat dissipation, since air is a good heat insulator, or they give rise to disruptive electrical charges in high-voltage applications, which can destroy the insulation. If the part being cast is fully coated with an insulating material, the process is called encapsulation.With electronic components, especially printed wiring boards (PWBs), thin layers are applied to protect them from harmful environmental influences. In these cases the process is known as “conformal coating”.
The following different resin systems exist & we at TARALAC supply the material of all resin types
- Polyester resins
- Polyurethane resins
- Silicone resins
- Epoxy resins
- Alkyd resins
- Acrylate resins (etc.)
Coatings for Transformers
The protective coating system used on power transformer radiators should be able to last without any appreciable maintenance during the first 10 to 15 years.
As per the current market scenario for transformers, our market is generally
- Domestic Tender Based Sales, Hence FAST PRODUCTION is required.
- Required Life Time Protection of Internal Walls of Tank from Hot Transformer Oil
- Complex Radiator Parts, Required Consistent Paint Coating Thickness (DFT)
- Protection from SEA and COASTAL Environment, Mostly for Exports to African and European Nations
- Outdoor Uses and Storage, Hence Required UV and MOISTURE Protection
- Heavy and Bulky Machinery, Hence More chances of SCRATCHES in Handling
- Implements Use in various Environment Conditions, Required CHEMICAL Protection
Depending upon various factors like Customer Specified Coating Requirements, Budgets, Quality of Pre Surface Treatment, Availability of Paint Shop, Skilled Painters and many others… We Recommend below Three Coating Systems for Optimum and Most Effective Results.
- Polyurethane & EPOXY Based Weather Resistance and Corrosion Protection Coating System
- High Solid PU & Epoxy Zinc Rich/ MIO based High Protective Coating System
- Fast Cured Synthetic Enamel based Conventional Coating System