What is UL Certification and Why Does it Matter?
Increased energy demands, ageing electrical systems, grid modernisation and the push for greater energy efficiencies are challenging the current electrical infrastructure.
Modernisation of transformers and electric motors is driving the demand for electrical insulation tapes. Key electrical equipment design stresses and assembly criteria highlight a need for insulating pressure-sensitive adhesive tapes, uniquely designed to meet thermal, dielectric, mechanical and chemical compatibility requirements. With a combination of backings and adhesives, our CHR® Products are UL recognised with thermal capabilities that range from class A (105°C) to class N (200°C).
For this article, we connected with Nirmal Patel, Product Manager, CHR Tapes at Saint-Gobain® Tape Solutions, to further explore the importance of UL listing in the electro-mechanical market and gain a better understanding of how UL class type impacts the product features, capabilities and most common applications.
In this article
First, tell us about the applicability of our products within the energy system, specifically as solutions for electrical insulation.
Yes, our products operate behind the scenes in power distribution, generation, and transmission. Primarily, they serve as insulation media for transformers, motors, and generators. These products help separate components to prevent short circuits or electrical arcing. They can act as spacers between coil wires and metal housings to prevent metal-to-metal contact within transformers, rotors, and stators, thereby avoiding electrical shocks or explosions in the power system.
Tell us about the importance of the UL listing.
Within the electromechanical market, the UL (Underwriters Laboratories) listing is one of the most recognised and respected certifications. UL recognitions are a requirement for OEMs manufacturing transformers, motors, and generators. UL 1446 is the standard that defines both guidelines and methodologies for evaluating the performance of electrical insulation materials as well as insulation systems. By understanding the UL class, we can better comprehend product interactions. We use a thermal class rating based on test results such as full thermal ageing tests, high-voltage full thermal ageing tests, and short-term thermal ageing tests, which demonstrate thermal degradation over time. The thermal classification specified by the UL recognition indicates the product's life expectancy at a certain temperature range, with the typical expected life of equipment at a rated temperature being approximately 20,000 hours.
Tell us about the high-performance electrical insulation tapes that are certified to classes defined by UL 1446.
We currently offer two brands of electrical insulation tapes to meet the demanding requirements of the electromechanical market, as well as other sectors such as aerospace, oil and gas, electronics, and industrial. These brands are the CHR and h-old® product ranges, which include a comprehensive portfolio of products for both North American and European markets.
Could you elaborate on what the UL letter class ratings mean?
A thermal class rating is issued based on test results, after which a UL certification report is provided. Essentially, it comes down to temperature range. For example, UL Class N (200ᵒC) and UL Class H (180ᵒC) fall into the high-temperature classification. This means they offer excellent temperature resistance, good dielectric strength, chemical resistance, and conformability. Within this high-temperature class, we have the following:
- Fluoropolymer Tapes, such as PTFE and FEP, which are generally ideal for insulating end windings in high-temperature motors and generators.
- Polyimide (PI) Tapes, featuring DuPont Kapton® and value grades of PI in full thickness ranges. These tapes have silicone adhesive and offer good conformability. They are often used for insulating end windings in high-temperature motors and generators.
- Glass Cloth Tapes, which have silicone adhesive, high tensile strength, and high thermal resistance. They are ideal for higher-temperature coil winding applications and are used to band layers of insulation together.
UL Class F (155ᵒC), B (130ᵒC), and A (105ᵒC) represent medium-temperature classifications. Some common products within this category include:
- PET Film/Non-woven and Paper Laminated Tapes, which are puncture-resistant, strong, and highly conformable, making them ideal for phase insulation and coil wrapping.
- PET Film Adhesive Tapes, available in various thicknesses and colours, with high tack properties for adhering to a wide range of substrates. They are flame-retardant, printable, and compatible with varnishes and resins. These tapes are commonly used for interlayer insulation, insulating smaller dry-type transformers or toroidal coils, and final binding.
- Acetate Cloth-backed Tapes, which feature a thermosetting rubber adhesive that provides excellent initial tack and high conformability. They are perfect for wrapping bobbins and smaller transformers.
- Double-sided Adhesive Tapes, which have good initial adhesion and electrical properties, making them ideal for securing insulating material during transformer manufacturing.
Why is choosing the right class of insulation important?
It is crucial to select the correct class of insulation. Using a lower class of insulation than required can lead to equipment damage or failure due to excessive heat. Conversely, using a higher class of insulation than necessary results in unnecessary added weight to the equipment and an avoidable increase in cost.
Engineers at the electrical equipment OEMs are under pressure to find products that meet both quality and on-time delivery requirements, as well as stringent safety standards. Collaborating with flexible suppliers is essential to support consistent market growth, address supply chain complexities, and respond swiftly to new opportunities.