Potting transformer is same as standard transformer principle just covered with flame-retardant plastic and filled with epoxy or PU glue in the box. With an potting/encapsulated design, every component is protected against dust, lint, moisture, and corrosive contamination.
What Is Transformer Potting?
The transformer potting consists of a box and glue between the transformer and casing. The biggest advantage of the potting transformer is its convenient use, good environmental isolation, attractive appearance, and good heat dissipation.
There are round enclosures or fill cases available for additional protection in harsh environments, and attractive uniform packaging is also available.
What’s Transformer Potting Meaning?
Potting is the process of filling or submersing a complete transformer using a compound material. Transformers can be bonded, sealed, potted, and coated with this glue.It is liquid before curing, and its viscosity varies with the material, performance and production process. Its use value is realized after the glue has completely cured, and it has many properties such as being waterproof, moisture-proof, dust-proof, insulating, thermal conductive, confidential, anti-corrosion, temperature resistant, and shock resistant.
What are there transformer potting material?
Potting compound for transformer is the material which we potting in the transformer.
Several types of transformer potting material exist. In this article, we will introduce epoxy resin material, polyurethane material, and silicone material.
1. An epoxy potting compound
It meets the EU ROHS standard and has high hardness, smooth surface, and good gloss, and is anti-theft, anti-corrosion, aging-resistant, thermal shock-resistant, waterproof, oil-proof, dust-proof, and waterproof.
Advantage:
Epoxy resin is generally hard, and some slightly modified epoxy resins are soft. Epoxy resin potting have the advantages of better adhesion to a substrate, better insulation, and good acid and alkali resistance. Epoxy resin can be used as a transparent material, with good light transmittance and low cost.
Disadvantages:
It is weakly resistance to cold and heat changes, and cracks are likely to occur as a result; after curing, the colloid has high hardness and brittleness, and high mechanical components are easily damage. Epoxy resin is hard because it is potted and cured, so it cannot be opened, making it a “lifetime” product. Transparent epoxy resins tend to be prone to yellowing under light or high temperatures and have poor weather resistance.
2. Polyurethane potting
Polyurethane potting (PU potting ) comprises polyols and diisocyanates of polyols, polyethers, and polydienes, as well as diols and diamines as chain extenders. An potting can generally be prepared using prepolymers and one-step processes.
Potting material made from polyurethane has a low hardness, moderate strength, good elasticity, water resistance, mildew resistance, shock resistance, transparency, excellent electrical insulation, good flame retardancy, and good adhesion to steel, aluminum, copper, nickel, tin and other metals. Transformers and circuits are protected by the potting material against vibration, corrosion, moisture and dust.
Advantage:
The polyurethane potting has a good low temperature resistance, a slightly soft texture, good adhesion to general potting materials, and is good to use in water-proof, moisture-proof, and insulating applications.
Disadvantages：
Having a poor high temperature resistance and easy to foam, vacuum defoaming must be used after curing; the surface of the colloid is not smooth and has poor toughness, and there is poor anti-aging ability, shock resistance, and ultraviolet ray resistance, and the colloid changes color easily.
3. A silicon potting compound
There are a number of types of silicone potting , each with different properties. There are silicone potting that are temperature-resistant, waterproof, insulating, optical, adhering to different materials, and soft and hard.A silicone potting can be added with functional fillers to give them electrical, thermal, and magnetic properties. Silicone potting are usually poor mechanically, but that is exactly what allows them to be easily maintained by simply prying open the potting and replacing the part. Generally, silicone potting can be made transparent, opaque, or colored to suit your specific needs. Potting compounds made from silicone are resistant to shock, electrical properties, waterproof properties, high and low temperature resistance, and anti-aging properties.
A two-pack silicone potting includes both condensation and addition types. As a general rule, condensation types have poor adhesion to components and the potting cavity, and volatile low-molecular-weight substances are produced during curing, resulting in a relatively noticeable shrinkage after curing. In addition type (silicon gel only), there is little shrinkage, no low molecular weight is produced during curing, and heating cures it quickly.
Advantage:
The silicone potting is soft after curing. It can eliminate most mechanical stress and provide shock absorption protection. Stable physical and chemical properties, good temperature resistance between -50°C and 200°C for a long time. Having excellent heat resistance, it can play a good protective role outdoors for more than a year, and does not yellow easily. After potting, it improves the insulation between internal components and lines, and it improves the transformer’s stability.
Disadvantages：
The adhesion is a little poor.
What is epoxy potting compound used for?
The epoxy encapsulant potting compound is commonly used in the protection of printed circuit boards and electronic devices in harsh environments. Chemical, mechanical, thermal, and electrical shock is less likely to damage electronic components when sealed with a high-quality epoxy potting compound.
