AEC Dry Type Transformers have excellent High-Temperature characteristics with UL approved 220°C rated Insulation System. Cores are fabricated from: Precision-Cut, Burr-Free, Grain Oriented, High Electrical Grade Silicon Steel. Dip & Bake: Each Dry Type Transformer consists of one or two cycles of Varnish Impregnation and baking stages which assures a reliable, long service life, for greater Electrical Strength.