National Electric Coil (NEC) products

National Electric Coil’s premier stator coil and bar design utilizes a proven, Class F, epoxy mica insulation system called NECCOBond-E. The NECCOBond line has been offered by NEC for many years, initially as a Class F polyester mica insulation system. However, in the last twenty years, NEC upgraded its design to a Class F epoxy system, hence the “E” in NECCOBond-E.

NECCOFlex-E multi-turn stator coils provide owners with the dielectric advantages of a traditional VPI coil but with a specially-engineered flexibility at the coil knuckles that eases its installation in a small bore machine or one with a tightly lapped winding. Small bore machines typically have slots that cannot always accommodate conventional multi-turn Roebel bars. The NECCOFlex coil exceeds the flexibility needed to properly install the coil cells in the slots. Compared to the alternative of using spliced half coils, a NECCOFlex winding requires only half the number of connections.

The hot-press, resin-rich manufacturing process produces multi-turn coils and Roebel bars that are best suited for industrial applications where product cost will need to be balanced against an acceptable degree of product reliably. Often, this may be the best option for owners of motors and generators that are rated up to 30 MW and operate at voltages up to 11 kv. However, for optimal reliability, care must be exercised in selecting a manufacturer.