High voltage device containing a flexible prepreg

• US 4,105,984 A
• Filed: 03/02/1976
• Issued: 08/08/1978
• Est. Priority Date: 06/22/1973
• Status: Expired due to Term

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Smith, James D. B., Kauffman, Robert N.
• Primary Examiner(s): Lovering, Richard D.
• Application Number:
  US05/663,036
• Time in Patent Office: 889 Days
• Field of Search: 336/205, 336/60, 174/25 C, 428/222, 428/413
• US Class Current: 336/60
• CPC Class Codes: H01B 3/48 fibrous materials fibre-reinforced plastics H01B3/47
• CPC Class Codes: H02K 3/24 with channels or ducts for cooling medium between the conductors
• CPC Class Codes: H02K 3/30 Windings characterised by the insulating material
• CPC Class Codes: H02K 3/34 between conductors or between conductor and core, e.g. slot insulation
• CPC Class Codes: Y10T 428/249922 Embodying intertwined or helical component[s]
• CPC Class Codes: Y10T 428/31511 Of epoxy ether

Abstract

A flexible, nontacky prepreg for use in bonding high voltage coils and inner cooling channels which comprises a fibrous mat material containing a high molecular weight epoxy and a sterically hindered anhydride. The resin comprises approximately 25 to 500% by weight of the fibrous mat material.

Claims

1. A high voltage electrical device comprising a plurality of high voltage coil strips having a groundwall insulation therearound, said coils having adjacent thereto and being bonded together by at least one prepreg comprising a fibrous mat containing an ungelled prepreg resin comprising epoxy resin having an epoxy equivalent weight greater than about 350 and at least one sterically hindered anhydride, and said groundwall having impregnated therethrough a styrene-epoxy-anhydride impregnating resin, the groundwall contacting at least a portion of said prepreg, said prepreg resin comprising from 25 wt.% to 500 wt.% of the prepreg and being compatible with the impregnating resin, so that the prepreg resin and the impregnating resin can be finally cured to integrally bond the prepreg and the groundwall together without delamination.

2. A high voltage device as set forth in claim 1 comprising at least two rows of coil strips having said prepreg positioned therebetween.

3. A device as set forth in claim 1, wherein said epoxy prepreg resin has an epoxy equivalent weight of between 360 to 400, a power factor of below 10% at 150°

C after curing, contains 18 to 29 parts liquid anhydride and 15 to 25 parts solid anhydride per 100 parts of epoxy resin, and also includes a nonhalide phosphonium salt accelerating agent.

4. A high voltage electrical device comprising a plurality of high voltage coil strips and inner-cooling channels having a groundwall insulation therearound, said coils and channels having adjacent thereto and being bonded together by at least one prepreg comprising a fibrous mat material containing an ungelled prepreg resin consisting essentially of epoxy resin having an epoxy equivalent weight greater than about 350 and at least one sterically hindered anhydride which is substantially unreactive with the epoxy resin at ambient temperatures, and said groundwall having impregnated therethrough a styrene-epoxy-anhydride impregnating resin, the groundwall contacting at least a portion of said prepreg, said prepreg resin comprising from 25 wt.% to 500 wt.% of the prepreg and being compatible with the impregnating resin, so that the prepreg resin and the impregnating resin can be finally cured to integrally bond the prepreg and the groundwall together without delamination.

5. A device as set forth in claim 4, wherein said prepreg epoxy resin has an epoxy equivalent weight value of between 360 to 400, a power factor of below 10% at 150°

C after curing, contains 18 to 29 parts liquid anhydride and 15 to 25 parts solid anhydride per 100 parts of epoxy resin, and said device comprises at least two rows of coil strips having said prepreg positioned therebetween.

6. A device as set forth in claim 4 wherein said prepreg resin is prepared from 100 parts by weight bisphenol A epoxy, 18-29 parts by weight 1-methyltetrahydrophthalic anhydride and 15-25 parts by weight hexahydrophthalic anhydride.

7. A device as set forth in claim 6 wherein said resin includes a nonhalide phosphonium salt accelerating agent.