Patent ID: 9022118
Filing Date: 2015-05-05
Classification: E21B,H01C,H05B,Y10T

Abstract:
1. A heater, comprising: a longitudinally continuous metallic tubular; three insulated electrical conductors located in the longitudinally continuous metallic tubular, each of the three insulated conductors comprising an electrical conductor at least partially surrounded by an insulation layer and an electrically conductive sheath at least partially surrounding the insulation layer; a metallic tape wrapped around the three insulated electrical conductors to hold the insulated conductors together; and one or more layers of electrical insulation at least partially surrounding each of the three insulated electrical conductors and the metallic tape in the longitudinally continuous metallic tubular along at least one length of each of the insulated electrical conductors, the one or more layers of electrical insulation being configured to electrically isolate the insulated electrical conductors from each other and from the longitudinally continuous metallic tubular along at least one of the lengths of the insulated electrical conductors, and wherein one or more of the layers of electrical insulation are configured to withstand operating temperatures of at least about 750° C.