Tape Wound Core Cases and Coatings Selection 

Non-Metallic Cases (Case/Coating Code "50")

For superior electrical properties, improved wearing qualities, and high strength, non-metallic cases are widely used as protection for the core material against winding stresses and pressures. Both phenolic and nylon types meet a minimum volt breakdown of 2000 volts wire-to-wire. The glass-filled nylon types can withstand temperatures to 200°C (392°F) without softening, while the phenolic materials will withstand temperatures up to 125°C (257°F) 

Aluminum Cases (Case/Coating Code "51")

Aluminum core cases have great structural strength. A glass epoxy insert, to which the aluminum case is mechanically bonded, forms an airtight seal. These core cases will withstand temperatures to 200°C (392°F), a critical factor in designing for extreme environmental conditions. 

Aluminum Case with GVB Epoxy Paint (Case/Coating Code "52")

This case is the same basic construction as the aluminum box, but in addition it has a thin, epoxy-type, protective coating surrounding the case. This finish adds no more than 0.015" to the OD, subtracts no more than 0.015" from the ID, nor adds more than 0.020" to the height. 

GVB epoxy paint finish offers a guaranteed minimum voltage breakdown of 2000 volts wire- to-wire. This coating will withstand temperatures as high as 200°C (392°F) and as low as -65°C (-85°F) with an operating life of greater than 20,000 hours. 

Uncased/Bare Cores (Case/Coating Code "53")

Uncased cores offer a maximum window area. They also offer a slightly smaller package and lower cost where slight deterioration of properties after winding can be tolerated. 

Because of the extreme sensitivity of nickel-iron cores to winding stresses and pressures, such cores are not available in an uncased state. Magnesil cores are not as susceptible to these pressures and are available without cases. 

Encapsulated (Red Epoxy) Cores (Case/Coating Code "54")

Encapsulated cores have a guaranteed minimum voltage breakdown of 1000 volts from core to winding. The temperature rating of this finish is 125°C (257°F). Only Magnesil cores are available in encapsulated form. This protection is a tough, hard epoxy which adheres rigidly to the core, allowing the winder to wind directly over the core without prior taping. A smooth radius prevents wire insulation from damage.