3M™ ThermaVolt Calendered Inorganic Insulating Papers


3M™ ThermaVolt Calendered Inorganic Insulating Papers

3M™ ThermaVolt Calendered Inorganic Insulating Paper meets the high performance requirements for high-temperature, dry-type transformers as major ground insulation in electrical systems rated through Class 220(R). ThermaVolt paper offers good dielectric characteristics, excellent partial discharge resistance and high thermal conductivity – making it especially suitable for use as interwinding insulation in strip-wound coils. ThermaVolt paper also is available bonded with polyester (PET) film for applications that require enhanced stiffness and formability, such as ground and layer insulation.

ThermaVolt insulating paper, made with inorganic material, has higher thermal conductivity than meta-aramid fiber insulation and can enable coil performance improvement. As an example, an existing coil design may have a lower temperature rise at the same power level or the coil load may be increased while the temperature rise is held constant. If the coil design is optimized for higher thermal conductivity, this may result in smaller conductor size and lower overall material cost, and potentially higher efficiency, depending upon the coil design.

ThermaVolt insulating paper and laminates are RoHS & REACH Compliant.



  • High thermal conductivity
  • Long-term voltage endurance
  • Low moisture absorption
  • RoHS & REACH compliant
  • UL 94 VO Rating* (*ThermaVolt insulating paper only. Does not include ThermaVolt Laminates.)

Typical Applications: 

  • Open ventilated dry-type transformers rated through Class 220(R)
  • Ground insulation
  • Core and outer wrap
  • Interwinding (or high-low) insulation
  • Turn insulation
  • Layer insulation