Electrical Insulating Paints: Characteristics and Uses

December 19, 2023

Electrical insulating paints are indispensable products in all sectors involving the presence of electric current. Ideal for insulating components, cables and surfaces from possible electricity dispersion, these paints help prevent short circuits, discharges and other risks associated with the flow of current.

But what are the characteristics that make electrical insulating paints so effective? And in which specific areas are they most widely used? In this article we will analyze in detail electrical insulating paints, illustrating their composition, properties and application areas.

insulating paints

Composition of Electrical Insulating Paints

Electrical insulating paints are made up of various components that help make them resistant to current flow:

  • Synthetic resins: form the paint binder and give it resistance and flexibility. The most used are epoxy, polyurethane and silicone resins.
  • Pigments: inorganic powder compounds that increase the insulating properties of the paint. The most common are titanium dioxide, zinc oxide, kaolin.
  • Solvents: used to adjust the viscosity of the paint. The most used solvents are acetone, toluene, xylene.
  • Additives: improve certain features such as UV radiation resistance, corrosion resistance, high temperature resistance.

The percentage of each component varies according to the type of electrical insulating paint and its end use. The key element to ensure good electrical insulation is the high concentration of pigments, which can reach up to 60-70% of the composition.

Characteristics of Electrical Insulating Paints

But let’s look in more detail at the properties that make electrical insulating paints so valuable for protecting components and surfaces from electrical hazards:

  • High electrical resistivity: the main feature of these paints, which prevent current flow between treated elements. Pigments provide resistivity up to 10^15 ohm*cm.
  • Barrier effect: create an insulating film that physically separates components, preventing dispersions and accidental discharges.
  • Dielectric strength: withstand high voltages without yielding and allowing current flow. The breakdown field is around 90-100 kV/mm.
  • Mechanical strength: good hardness and scratch, abrasion and impact resistance. Do not flake over time.
  • Thermal resistance: maintain insulating properties even at high temperatures, up to 155°C continuously and over 200°C for peaks.
  • Environmental resistance: not highly affected by humidity, UV rays, chemicals. Therefore suitable for indoor and outdoor use.

Thanks to these qualities, electrical insulating paints provide effective protection against electrical hazards in many applications.

Main Uses of Electrical Insulating Paints

Insulating paints are used in all fields requiring adequate protection of components and surfaces from the dangers of electricity. Here are the main areas where these products are used:

  • Insulation of electrical cables: the paints protect cables from short circuits and dispersion to ground. Ideal for power cables, bus-bars, windings of motors and transformers.
  • Insulation of electronic components: keyboards, circuit boards, terminals and other electrical and electronic components are insulated with these paints to prevent damage.
  • Insulation of metal supports: metal structures, electrical panels, shelves, brackets and other metal supports intended to hold live parts are insulated to avoid dispersions.
  • Insulating paint coating of floors and walls: to create electrically safe environments such as power plants, cabins, laboratories, the surfaces are treated with insulating paints.
  • Maintenance of electrical machinery: the paints restore the insulating properties of windings, contacts and other parts subject to wear on motors, generators, alternators.
  • Insulation of high voltage equipment: transformers, switches, disconnectors and other high voltage equipment (up to 1000V) are insulated with special paints.

In addition to these established uses, insulating paints are also finding application in emerging fields such as electric mobility, industrial electrification, wireless charging systems and wind power.

Types of Electrical Insulating Paints

There are various types of electrical insulating paints, which differ in composition and properties according to their uses:

  • Epoxy resin-based insulating paints: excellent mechanical, chemical and dielectric properties. Ideal for insulating windings of motors and transformers.
  • Polyurethane insulating paints: very high resistivity and flexibility. Suitable for insulating vibration-prone components.
  • Silicone insulating paints: excellent thermal stability up to 200°C. For high temperature insulation.
  • Acrylic insulating paints: fast drying, good environmental resistance. To insulate metal supports.
  • PTFE-based insulating paints: resistant to extreme temperatures (-70°C/+280°C), suitable for insulating electrical contacts.
  • Insulating paints for flooring: non-slip and resistant to traffic, oils, chemicals. For industrial environments.

In addition to single-component paints, there are also two-component formulations (base + catalyst) with improved performance. Insulating paints are applied by brush, roller or spray on clean and degreased surfaces.

Choosing Electrical Insulating Paint

To choose the most suitable electrical insulating paint for a specific application, several factors must be considered:

  • Working voltage: for low voltage up to 1000V, acrylic or polyurethane paints are indicated; for medium voltage up to 36kV, epoxy paints are preferable; for high voltage silicone paints.
  • Operating temperature: at room temperature all paints are suitable; at higher temperatures silicone or PTFE paints are needed.
  • Surface type: for metal, epoxy or acrylic paints are indicated; for plastic and rubber, polyurethane paints; for ceramics, silicone paints.
  • Environment of use: for outdoor use acrylic or silicone paints that are more resistant to atmospheric agents are preferred; for indoor, epoxy and polyurethane paints are also fine.
  • Mechanical requirements: if high mechanical properties are required, epoxy or polyurethane paints are preferable.
  • Application method: single-component paints for simple applications; two-components for higher requirements.
  • Drying: if fast drying is needed, acrylic or polyurethane paints are indicated.

In addition to the type, it is important to consider the thickness of the insulating film required: it ranges from a minimum of 80-120 microns for low voltage, up to 1 mm and over for high voltage. Finally, for critical applications it is advisable to carry out preliminary tests.

Maintaining Insulated Surfaces

To ensure long-lasting electrical protection, proper maintenance of insulated surfaces with special paints is necessary. Periodically it is necessary to:

  • Visually check the coating integrity, making sure there are no cracks, flaking or swelling.
  • Promptly repair any damaged areas, to prevent infiltration and localized dielectric losses.
  • Perform electrical tests to verify that the insulation maintains the prescribed values of surface resistance and dielectric strength.
  • Remove dirt and deposits that can create current leakage paths.
  • Apply a new layer of insulating paint if the previous one is worn or no longer provides protection.

By choosing the right electrical insulating paint and taking care of proper maintenance, it is possible to minimize electrical hazards and achieve maximum protection of components and surfaces in the presence of dangerous voltages.

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