An insulator is a material that restricts or inhibits the flow of electricity, heat, or sound. Even though the engineering plastics that Dotmar specialise in are thermal and sound insulators, our materials lend themselves to electrical insulation.
These materials have high electrical resistance, which means they do not allow electrons to flow easily through them, as well as high dielectric strength, i.e. the resistance to breaking down by “sparking through”.
Insulators are vital in electrical systems to prevent the loss of energy through unwanted conduction and to ensure safety by containing and directing the flow of electricity.
Benefits of Plastic insulators
Resistance – engineering thermoplastics tends to volumetric and surface resistance of in the order of 1012 to 1014 Ω.cm and Ω respectively.
Dielectric Strength – traditional electrical insulating materials tend to have dielectric strength of approximately 12 kV/mm, while engineering thermoplastics commonly range from 15 kV/mm to 45 kV/mm.
Chemical Resistance – For electrolysis applications (or similar) where chemicals are present, thermoplastics, such as Polystone P, Trovidur EC-N, and Tetron S, have excellent chemical resistance and generally prove to be an ideal solution to solve for electrical insulators in chemical environments.
Temperature Resistance – Materials such as Tetron S, offer not just high electrical resistance and dielectric strength, but also allows for continuous operation up to 2600C, and short-term temperatures of up to 3100C.
Dotmar has qualified engineers that can provide direct support with plastic insulator material selection, including conducting calculations for thicknesses required to resist breaking down by “sparking through”.
Sleeve Insulators
A bush style, used to insulate a bolt or shaft from the surrounding structure.
Stand-Off Insulators
Designed to support and separate electrical conductors or components at a specific distance.
Electrolysis Bar Insulation
In addition to electrical insulation, often chemical and temperature resistance is required.
Transmission Lines
Transmission Lines
Busbar Insulation Blocks
Often requiring very high Dielectric strength to withstand the high voltages
Cathode Edge Strip
Prevents build up on the edge of a cathode in applications such as copper plants and smelting.
Material selection is a critical consideration when choosing a plastic for electrical insulators, as it directly impacts the ability for the material to function. Here are some key material selection considerations for plastic insulators:
Resistance
Typically, the higher the volumetric resistance the better the insulation characteristics and therefore the ability to perform as an insulator, but there are also applications where additional electrical functionality is required. These can be anti-static; used to eliminate the risk of sparking in an explosive environment, and ESD (Electro Static Dissipative), which is used to dissipative static charge in a controlled fashion to protect sensitive electrical equipment or components.
Dielectric Strength
The dielectric strength of a material is a measure of its ability to resist electrical breakdown (sparking through). This is a function of the resin as well as the thickness of the insulating section.
Chemical Resistance
Some applications such as electrolysis equipment and electroplating, will make use of chemicals, therefore it is imperative that the material is not affected by the chemical, as this will diminish the electrical properties of the insulating material.
Temperature
At elevated temperatures the mechanical strength of the material is influenced in the short term, but long-term exposure to elevated temperatures can result in heat aging, which can further compromise the mechanical properties, as well as the electrical insulation characteristics.
Regulatory Requirements
Does the application have regulatory requirements such as food contact, drinking water, anti-static or flame retardant. The food industry may also require materials to be metal detectable, x-ray detectable and/or visually detectable by being coloured blue.
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