ELECTRIC RESISTANCE HEATING CABLE

• US 3,646,322 A
• Filed: 01/05/1971
• Issued: 02/29/1972
• Est. Priority Date: 02/13/1970
• Status: Expired due to Term

• Current Assignee: Bernardus Willebrordus Speekman
• Original Assignee: Bernardus Willebrordus Speekman
• Inventors: Speekman, Bernardus Willebrordus
• Primary Examiner(s): Gilheany, Bernard A.
• Assistant Examiner(s): Bell, F. E.
• Application Number:
  US05/103,978
• Time in Patent Office: 420 Days
• Field of Search: 219/545,548,549,528 338/210 336/222,223
• US Class Current: 219/549
• CPC Class Codes: H05B 3/56 Heating cables

Abstract

An electric resistance heating cable having alternating sectors of different temperature during use obtained by winding a heating wire having sectors of comparatively high- and comparatively lowelectric resistances on a core of an electrically insulating material and by enveloping the assembly with an electrically insulating covering.

Claims

1. An electric redistance heating cable comprising a flexible core of electrically insulating material, a heating wire wound helically around said core and extending throughout the length of the cable and a covering of electrically insulating material, the cable being divided into at least two groups of alternating sectors extending in the longitudinal direction of the cable, which sectors assume mutually different temperatures during use of the cable, said heating wire comprising sections having a comparatively high resistance per unit of length alternated by sections having a comparatively low resistance per unit of length.

2. The electric resistance heating cable as claimed in claim 1, wherein the heating wire comprises a wire having a comparatively high resistance per unit of length which is provided at regular distances with envelopes having a comparatively low resistance per unit of length and extEnding in the longitudinally direction of the wire.

3. The electric resistance heating cable as claimed in claim 1, wherein the heating wire comprises a wire having a comparatively high resistance per unit of length which is provided at regular distances with envelopes having a comparatively low resistance per unit of length and extending in the longitudinal direction of the wire, and further comprising an envelope extending throughout the length of the wire comprising a material which is still resistant to oxidation at the highest temperature which is reached during operation of the cable.