Nomex® for Motor Insulation Helps Extend Equipment Life


When it comes to motor insulation, DuPont™ Nomex® brand papers and Nomex® based laminates are an ideal choice for virtually any motor, helping to increase reliability and extend equipment service life.

The outstanding thermal performance and excellent mechanical strength of Nomex® are the reasons why it is a preferred motor insulation for all types of motors—from AC and DC to random and form wound, in sizes ranging from miniature servo motors to 13.6 kV industrial drives.

In addition to its long history of proven performance in conventional motor insulation applications, Nomex® insulation is helping original equipment manufacturers (OEMs) to address the increased power density requirements and harsh operating conditions of motors used in hybrid electric vehicles (HEVs).  

With its excellent dielectric strength, Nomex® insulation can endure the electrical stresses that are commonly encountered in HEVs due to the use of inverters.  And, Nomex® paper is compatible with the oils and automotive transmission fluids (ATFs) often used in HEVs.

Today, more motors are being driven by electronic systems to achieve higher efficiency. This creates high-frequency spikes that put greater stress on the motor insulation materials. DuPont has developed specialized Nomex® papers to address this requirement.

Exceptional Thermal Protection

The use of Nomex® for motor insulation can help prevent premature motor failure and equipment downtime.  That’s because Nomex® does not shrink, embrittle, soften or melt during short-term exposure to temperatures as high as 300°C, and because it maintains good insulating properties continuously at 220°C for 10 years. 

This high-temperature durability helps to allow miniaturization and/or higher power density of electrical drive motors and enables long-term electrical dependability.  This also helps OEMs to reduce the size and weight of components such as traction motors used in high-speed trains and in the emerging electric vehicle marketplace.

Superior Mechanical Toughness

The excellent mechanical strength and resilience of Nomex® insulation help extend the service life of motors subjected to harsh operating conditions, such as the severe shock and vibration seen in steel mill drives, railway traction and automotive motors. 

An added benefit of the superior mechanical toughness of Nomex® is the manufacturing efficiencies that can be gained from automatic insertion of slot liners.

Chemical Compatibility

Nomex® paper is compatible with all classes of varnishes and adhesives, transformer fluids, lubricating oils, automatic transmission fluids (ATFs) and refrigerants.

Typical Applications in Motors

Nomex® papers and Nomex® based laminates are used in motors as:

· Slot liners
· Wedges and midsticks
· Phase insulation
· Conductor insulation
· Coil separators
· OCP tape
· Tubing
· Pole insulation
· Turn insulation
· Main wall insulation

Typical Motor Equipment

Nomex® papers and Nomex® based laminates are used in all types of motors, including:

AC Motors

· AC Industrial—Class F
· AC Industrial—Class H
· Low voltage traction (random wound)
· High voltage traction (form wound)
· High voltage motor
· Automotive starter
· Automotive alternator
· Automotive motor for EV/HEV
· Appliance
· Auxiliary motors

DC Motors

· Machine tool
· DC Traction (repair)



Nomex® paper properties

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Nomex® 800 Series

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DuPont brands

Nomex® Electrical Insulation

Nomex® paper and pressboard have earned a reputation for delivering superior quality and proven reliability for a wide range of electrical insulation applications, meeting the ever-increasing demands of a changing world.

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Industry segments

Power Generation and Distribution

DuPont offers a wide range of high-performance products that help optimize the performance and extend the service life of power generation and distribution equipment.

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