Insulating paper is a crucial insulating material used in motor products, albeit in small quantities. It is used for slot insulation, interlayer insulation, and phase-to-phase insulation in three-phase motors. Different types of insulating paper should be selected for motors with different heat resistance ratings. The most commonly used are composite insulating papers such as DMD, NMN, and NHN. With the increasing requirements for insulation and heat resistance performance, new insulating materials have emerged, such as TFT composite insulating paper.
Insulating materials should possess properties such as high toughness, excellent dielectric properties, high thermal conductivity, ease of insertion, certain hardness, resilience, and suitable heat resistance. Different application environments place different requirements on insulating materials; for corrosive environments, the corresponding insulating materials must have a certain degree of corrosion resistance.
In practical use, every effort should be made to maintain the original state of the insulation material, avoiding wrinkles, delamination, blistering, and other phenomena that affect insulation performance. Good insulation material can effectively extend the service life of a motor; conversely, insulation material that does not meet the requirements will significantly reduce the motor's lifespan. Insulating paper is a general term for electrical insulating paper. It is used as an insulating material for cables, coils, and other electrical equipment. In addition to having good insulation performance and mechanical strength, each type of insulating paper has its own characteristics.
Composition and properties of different insulating materials
●DMD Insulation Paper (Class B Insulation). This product is a composite insulation material made of a layer of polyester film coated with adhesive, one side of which is a polyester fiber non-woven fabric composite, and then calendered. It is abbreviated as DMD.
●NMN insulating paper (Class F insulation). It is a flexible composite material composed of a middle layer of polyester film and two layers of Nomex paper, with a heat resistance rating of Class F (155℃). It has good mechanical properties, such as tensile strength and edge tear resistance, as well as good electrical strength. Its smooth surface ensures fault-free operation when using automatic production lines for low-voltage motors. It is mainly used for inter-slot, slot cover, and phase-to-phase insulation in low-voltage motors, and can also be used as interlayer insulation for transformers or other electrical appliances.
NOMEX paper, also known as NOMEX, is a synthetic aromatic amide polymer insulating paper with high mechanical properties, flexibility, and good electrical properties. It retains its characteristics at high temperatures and is widely used in generators, transformers, electrical equipment, electromechanical systems, and household appliances.
The "DuPont paper" commonly known in the market is actually made from two materials produced by DuPont: one is high-density polyethylene material called Tyvek, and the other is meta-aramid fiber material called Nomex.
●NHN insulating paper (H-class insulation). It is a flexible composite material composed of a middle layer of polyimide film and Nomex paper on both sides, with a heat resistance rating of H (180℃). It has good mechanical properties, such as tensile strength and edge tear resistance, as well as good electrical strength. Its surface is smooth, ensuring fault-free operation when using automatic unwinding machines in the production of low-voltage motors. NHN is mainly used for inter-slot, slot cover, and phase-to-phase insulation of high-heat-resistant motors. It can also be used as interlayer insulation for transformers or other electrical appliances.
●TFT composite materials. These are a series of high-performance insulating paper composite products. A typical structure is a thin layer of TUFQUIN insulating paper laminated with polyester film on both sides, used in high-temperature insulation systems. Typically used in Class H motors or engines for slot insulation and groove insulation, this product offers a balance of electrical, physical, and thermal properties, improving equipment reliability through enhanced insulation material performance.
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