High voltage winding with protection against glow discharge

• US 3,891,880 A
• Filed: 05/18/1973
• Issued: 06/24/1975
• Est. Priority Date: 06/16/1972
• Status: Expired due to Term

• Current Assignee: Helmut Britsch
• Original Assignee: Helmut Britsch
• Inventors: Britsch, Helmut
• Primary Examiner(s): Skudy, R.
• Application Number:
  US05/361,648
• Time in Patent Office: 767 Days
• Field of Search: 310/196,254,200,258,208,259,214,216,215,217,218,45 161/91,90,163,189 336/70 179/110,140-144 317/2
• US Class Current: 310/196
• CPC Class Codes: H01F 5/06 Insulation of windings
• CPC Class Codes: H02K 3/40 for high voltage, e.g. affording protection against corona discharges
• CPC Class Codes: Y10S 174/22 Winding per se
• CPC Class Codes: Y10S 174/29 having a semiconductive layer
• CPC Class Codes: Y10T 442/3252 Including synthetic polymeric strand material

Abstract

An insulated high-voltage winding of an electrical machine is protected against glow discharge by application thereto of a wound-on tape of semi-conductive material which has been prestretched in its longitudinal direction and which is thereafter contracted by heat treatment. In one embodiment, the tape is a woven structure in which the warp threads consist of a prestretched, non-heat set polymer such as polyester and the weft threads being of the same material but dimensionally stable. In a modified embodiment for the woven tape, the weft threads consist of an inorganic material such as glass or asbestos. According to another embodiment the tape is constituted by sections cut from a foil which is pre-stretched in a longitudinal direction and nonheat-set, the foil being made from polymerous carbon fluoride, or polyester or polyvinylidenefluoride. The surface of the foil sections to be wound onto the winding insulation can be pretreated such as by cauterization or corona discharge to improve its adhesive character.

Claims

1. An insulated high-voltage winding installed in the slots of the stator component of an electrical machine and wherein external glow-protection means are provided between the insulation on said winding and the slotted portion of said stator, said external glow-protection means being constituted by a wound-on impregnatable woven tape of an electrically semiconductive material covering the entire surface of said winding insulation, the warp threads of said woven tape consisting of a pre-stretched non-heat set and heat contractible filamentary material having an organic polymeric structure and the weft threads thereof consisting of dimensionally stable filaments.

2. A glow-protected insulated high-voltage winding as defined in claim 1 wherein the that contraction factor of wrap threads of said woven tape amounts to between 1 and 12 percent, and preferably between 2 and 5 percent.

3. An insulated glow-protected high-voltage stator winding as defined in claim 1 wherein the warp threads of said glow-protection woven tape are constituted by pre-stretched non-heat set filaments of polyester and the weft threads consist of dimensionally stable filaments of the same material.

4. An insulated glow-protected high-voltage stator winding as defined in claim 1 wherein the weft threads of said glow-protection tape consist of dimensionally stable filaments of an inorganic material.

5. An insulated glow-protected high-voltage stator winding as defined in claim 1 wherein the weft threads of said glow-protection tape consist of dimensionally stable filaments of glass.

6. An insulated glow-protected high-voltage stator winding as defined in claim 1 wherein the weft threads of said glow-protection tape consist of dimensionally stable filaments of asbestos.

7. An insulated high-voltage winding installed in the slots of the stator component of an electrical machine and wherein external glow-protection means are provided between the insulation on said winding and the slotted portion of said stator, said external glow-protection means being constituted by a wound-on impregnatable tape of an electrically semi-conductive material covering the entire surface of said winding insulation, said tape being constituted by sections taken from a foil of a non-heat set polymeric material which is pre-stretched in a longitudinal direction and heat contractible in such direction.

8. An insulated glow-protected high-voltage stator winding as defined in claim 7 wherein said glow-protection foil consists of polymeric carbon fluoride.

9. An insulated glow-protected high-voltage stator winding as defined in claim 7 wherein said glow-protection foil consists of polyvinylidenfluoride.

10. An insulated glow-protected high-voltage stator winding as defined in claim 7 wherein said glow-protection foil consists of polyester.

11. An insulated glow-protected high-voltage stator winding as defined in claim 7 wherein the insulation on said winding consists of a glass-mica tape and wherein the surface of said glow-protection foil at the side thereof in contact with the glass-mica tape insulation on said winding is pre-treated to facilitate adhesion thereof to said tape insulation.

12. An insulated glow-protected high-voltage stator winding as defined in claim 11 wherein said glow-protection foil is constituted by fluorinated polymers and the surface thereof in contact with the glass-mica tape insulation is pre-treated by cauterization.

13. An insulated glow-protected high-voltage stator winding as defined in claim 11 wherein said glow-protection foil is constituted by polyester and the surface thereof in contact with the glass-mica tape insulation is pre-treated by a glowdischarge.