Electrical Composite Insulation Paper Performance

Flexible composite materials are laminates that combine the strengths of multiple materials—typically films, papers, and non-wovens—to create superior electrical insulation. In motors and generators, these thin, pliable insulation papers are critical for slot, phase, and layer insulation. Their performance directly dictates the reliability, efficiency, and lifespan of the final electrical product. This guide explains why these materials are essential and provides a detailed breakdown of key types like DMD, NMN, and NHN.

The Critical Role of Insulation in Electric Motors

While constituting a small fraction of a motor's mass and cost, flexible composite insulation materials are non-negotiable for safety and performance. They are meticulously placed in three key areas:

• Slot Insulation: Lines the stator or rotor slots, protecting the windings from the grounded core.

• Phase Insulation: Separates windings of different phases to prevent short circuits.

• Layer Insulation: Used in transformers and some windings to isolate conductive layers.

A failure in any of these areas leads to immediate motor breakdown. Therefore, the choice of insulation is a foundational engineering decision.

Common Flexible Composite Insulation Materials

The following is a detailed introduction to the composition and properties of several common insulating materials:

• DMD Insulating Paper (Class B & F Insulation): Composed of polyester film, adhesive, and polyester fiber nonwoven fabric, it has excellent composite insulation performance and is suitable for low-voltage motors.

• NMN Insulating Paper (Class F & H Insulation): Composed of polyester film and Nomex paper, it has a heat resistance rating of Class F (155℃) or Class H(180℃), good mechanical properties and electrical strength, and is suitable for low-voltage motors.

• NOMEX 410 Paper: A synthetic aromatic amide polymer insulating paper with high mechanical properties, flexibility, and good electrical properties, suitable for generators, transformers, etc.

• NHN insulating paper (H-class insulation): It is composed of polyimide film and Nomex paper, with a heat resistance rating of H (180℃), and is suitable for motors with high heat resistance.

Why "Flexible Composites"? 

Insulating materials must possess high toughness, excellent dielectric properties, high thermal conductivity, ease of installation, appropriate hardness and resilience, and a suitable heat resistance rating. Different application environments place varying requirements on insulating materials; especially in corrosive environments, insulating materials must possess a certain degree of corrosion resistance.A successful motor insulation material must be a multifaceted performer. Flexible composite materials are specifically engineered to meet this demanding checklist:

1. High Dielectric Strength: To withstand high voltages and electrical stresses.

2. Thermal Endurance: Must perform reliably at the motor's operating temperature (Class A to H).

3. Mechanical Toughness & Flexibility: Resists tearing and punching during automated assembly and conforms tightly to uneven surfaces.

4. Thermal Conductivity: Helps dissipate heat from the windings, a key factor in motor longevity.

5. Environmental Resistance: Must withstand humidity, oils, and corrosive chemicals present in operational environments.

6. Dimensional Stability: Will not shrink, blister, or delaminate under thermal cycling.

Handling is Key: Even the best material can fail if compromised during installation. Wrinkles, creases, or punctures create weak points for electrical tracking and premature failure.