Applications of NMN Insulation Paper in Low-Voltage Motors and Transformers

NMN insulation paper, as a high-performance insulation material, is made by laminating polyester film (commonly PET) with polyaramid paper (such as Nomex® or similar materials). In this composite structure, “N” stands for polyaramid paper (Nomex® type) and “M” stands for polyester film (Mylar® type). Through lamination or adhesive bonding processes, the two layers are firmly combined, creating a composite insulation material that integrates the advantages of both. This ensures reliable protection for the safe and stable operation of electrical equipment.

Application in Low-Voltage Motors

Low-voltage motors cover a wide range of fields, including industrial drive motors, household appliance motors, and new energy vehicle drive motors. In these applications, NMN insulation paper plays a vital role, mainly serving as slot insulation, interlayer insulation, and phase-to-phase insulation.

1. Slot Insulation (Slot Liner)

Slot insulation is applied to the inner wall of stator or rotor core slots, acting as the main insulation barrier between conductors (enameled wires) and the iron core. It effectively prevents ground breakdown. NMN insulation paper demonstrates significant advantages in slot insulation applications:

High Dielectric Strength:

The PET film in the middle layer provides NMN insulation paper with excellent electrical insulation performance, enabling it to withstand voltages and surge impulses during motor operation, thereby ensuring electrical safety.

Outstanding Mechanical Strength:

During the automated winding process, enameled wires are inserted into slots at high speed. Thanks to its abrasion resistance and tear strength, NMN insulation paper can resist scratches and punctures, effectively preventing insulation failures caused by damage and ensuring long-term reliable motor operation.

Good Thermal Resistance:

Typically rated as Class H (180 °C), NMN insulation paper allows motors to operate at higher temperatures. This is especially important for enclosed motors, motors with poor cooling, or motors operating under heavy loads. Its heat resistance helps increase power density or extend service life.

Excellent Flexibility:

Easy to bend and fit into the core slot profile, NMN insulation paper adapts well to automated production processes, thereby improving manufacturing efficiency.

2. Interlayer Insulation/Phase Insulation

Interlayer insulation and phase insulation separate windings of different phases to prevent short circuits. In addition to the electrical and mechanical properties mentioned above, NMN insulation paper's excellent stiffness (both hard and flexible) makes it easier to cut, insert, and secure between windings of different phases. This provides reliable physical isolation and ensures safe insulation between motor phases.

Applications in Low-Voltage Transformers

NMN insulation paper is also widely used in low-voltage transformers, such as control transformers, power transformers, and instrument transformers, primarily for interlayer and segment insulation.

1. Interlayer Insulation

In transformer windings, a layer of insulation paper is applied between every one or several layers of conductors to prevent voltage breakdown between layers. NMN insulation paper offers the following advantages for interlayer insulation:

High dielectric strength: Even with thin insulation layers, NMN insulation paper provides sufficient insulation margin, helping to reduce the overall size of the transformer and increase its power density. 

Strong Thermal Stability: Transformers generate heat during long-term operation. The high-temperature resistance of NMN insulation paper ensures long-term stability of its insulation performance, effectively preventing insulation failure caused by overheating and aging, ensuring safe and reliable operation of the transformer.

High Tensile Strength: During the winding process, the material is subjected to tensile forces. NMN insulation paper has high tensile strength and is not easily broken, meeting the process requirements of transformer winding.

2. Barrier Insulation (Sectional/Isolation Insulation)

Barrier insulation is mainly used to separate the primary and secondary windings or to isolate different voltage-level winding sections. With its reliable safety performance, NMN insulation paper ensures complete separation between high- and low-voltage windings, making it one of the key materials for guaranteeing the safe operation of transformers.

Thanks to its excellent electrical, mechanical, and thermal properties, NMN insulation paper has been widely applied in low-voltage motors and transformers, providing strong support for performance improvement and safe operation of electrical equipment. With the continuous development of the electrical industry, NMN insulation paper is expected to play an increasingly important role in more application fields.