How to Select NHN Insulation Paper for Dry-Type Transformers

Applications of NHN Insulation Paper in Dry-Type Transformers  NHN insulation paper is a composite made of Nomex ara...

Applications of NHN Insulation Paper in Dry-Type Transformers 

NHN insulation paper is a composite made of Nomex aramid paper – polyimide film (PI) – Nomex aramid paper, with a thermal class of Class H (180°C). It is widely used in dry-type transformers where high heat resistance, strong mechanical strength, and excellent dielectric properties are required. Compared with conventional materials such as DMD and NMN, NHN offers superior stability, lifespan, and environmental resistance, making it a preferred insulation material for medium- and high-end transformers.

1. Typical Applications of NHN Insulation Paper in Dry-Type Transformers

Interturn Insulation

Used between turns of the winding
Maintains structure under high temperature and overload
Reduces the risk of partial discharge

Layer Insulation

Applied between winding layers
High mechanical strength supports pressure during casting or winding
Minimizes insulation damage caused by thermal and mechanical stress

Phase Insulation

Common in cast-resin dry-type transformers
Class H rating ensures safe operation at high temperatures
Enhances safety margin between phases

End-Turn Reinforcement

Coil end-turns have high electrical stress and are prone to partial discharge
NHN wrapping, liners, or corner protection helps suppress partial discharge

Spacers, Liners, and Insulating Gaskets

Used as structural insulating spacers and pads
Low moisture absorption and excellent aging resistance make it ideal for long-term operation

Slot Insulation and Binding Insulation

NHN is flexible, easy to cut, and suitable for slot liners and binding strips
Maintains mechanical toughness and withstands thermal shock for years

2. How to Select NHN Insulation Paper for Dry-Type Transformers

To ensure long-term reliability, material selection should consider the following factors:
Thickness Selection (Common Range: 0.08–0.25 mm)

Thicker materials offer stronger insulation and mechanical performance but have reduced flexibility.

Dielectric Strength & Thermal Class

NHN is rated Class H (180°C)

Suitable for high-temperature and high-overload dry-type transformers
For designs with lower temperature rise, NMN or DMD (Class B or F) may be more economical
NHN is preferred in high-humidity, dusty, or high thermal-shock environments

Width, Roll Form, and Processing Requirements

Confirm the following specifications:
Width (commonly 1000 mm)
Roll length (50 m, 100 m, 200 m, etc.)
Whether die-cut parts are needed (gaskets, rings, spacers)
Whether adhesive-backed processing is required
Complex transformer designs benefit from die-cut NHN parts to improve assembly efficiency and consistency.

Certifications and Material Quality

Recommended materials should have:
UL-certified Class H rating
Reliable Nomex aramid paper source
High-quality polyimide film
These ensure long insulation life and stable partial discharge performance.

Cost-Performance Matching

3. Key Advantages of NHN (Compared with NMN / DMD)

Higher thermal class (Class H 180°C)
Stronger dielectric strength and safety margin
Low moisture absorption and superior aging resistance
Better mechanical and thermal shock performance
Service life 2–3× longer than NMN/DMD
These advantages significantly enhance transformer reliability.

4.Select manufacturer

XUJUE ELECTRICAL  is a professional manufacturer of high-quality electrical insulation materials with more than 65 years of manufacturing experience.

If you are looking for NHN insulation paper, please contact us and provide the product specifications, thickness and purpose you need, you can get detailed product information and quotation, and also send samples free of charge.