Transformer completely coated by casting thermoplastics - having same heat expansion coefft. as coil and pref. of same material

摘要

In a transformer comprising a core, a coil former or thermoplastic resin set up on part of core and coil windings applied on coil, the transformer is coated completely by a layer of thermoplastic resin having the same heat expansion coefft. as the material of coil former as well as good wetting action towards the coil material. Resin layer pref. consists of the same material as that of coil. The thermoplastic material of layer and of core can be polyamide, polyester, polyethylene, polypropylene, polystyrene, polyactal, PMMA, ABS-resin, styrene-acrylonitrile copolymer or polyurethane. Blisters, local overheating and cracks are avoided. The transformer is water-tight, resistant to chemicals and has high insulating power.