Corona shielding strip for a high-voltage rotating electrical machine
Various embodiments of the teachings herein include a corona shielding tape for further processing to give an insulation system comprising an impregnated winding with potential control via outer corona shielding “AGS” and/or internal potential controller “IPS” and/or terminal corona shielding “EGS”, the insulation system being producible by impregnating the winding with an anhydride-free and resin-based impregnating agent at 45-85° C. and under reduced pressure. The corona shielding tape may include: a carrier tape; an electrically conductive and/or partly conductive filler in a polymer matrix; and a tape accelerator suitable for curing and/or gelation of the impregnating agent. The polymer matrix contains at least one polyvinylalcohol and/or a polyvinylalcohol copolymer. The accelerator is selected from the group consisting of: superacids and superacid salts suitable for acceleration of a cationic homopolymerization of the resin-based anhydride-free impregnating agent.
1. A corona shielding tape for further processing to produce an insulation system comprising an impregnated winding with potential control via outer corona shielding “AGS” and/or internal potential controller “IPS” and/or terminal corona shielding “EGS”, the insulation system produced by impregnating the winding with an anhydride-free and resin-based impregnating agent at 45-85° C. and under reduced pressure, the corona shielding tape comprising:
a carrier tape;
a tape adhesive;
an electrically conductive and/or partly conductive filler in a polymer matrix; and
a tape accelerator suitable for curing and/or gelation of the impregnating agent;
wherein the filler comprises at least one component selected from the group consisting of: antimony-doped tin oxide, silicon carbide, and aluminum-doped silicon carbide;
the polymer matrix contains at least one polyvinylalcohol and/or a polyvinylalcohol copolymer;
the tape adhesive, the filler, and the tape accelerator are inert to each other and therefore stable in storage at a temperature from 6 degrees to 23 degrees C. for six months; and
the accelerator comprises at least one of a superacid or a superacid salt including a sulfonium cation suitable for acceleration of a cationic homopolymerization of the resin-based anhydride-free impregnating agent.
2. The corona shielding tape as claimed in claim 1 , wherein a basis of the resin-based impregnating agent comprises an anhydride-free epoxy resin.
3. The corona shielding tape as claimed in claim 1 , wherein sulfonium cation includes an aryl radical.
4. The corona shielding tape as claimed in claim 1 , wherein multiple tape accelerators are present in combination.
5. The corona shielding tape as claimed in claim 1 , wherein the sulfonium cation includes an arylalkyl-sulfonium cation.
6. The corona shielding tape as claimed in claim 1 , further comprising a dialkylarylsulfonium cation.
7. The corona shielding tape as claimed in claim 1 , further comprising an aryl radical of a sulfonium cation in substituted form.
8. The corona shielding tape as claimed in claim 1 , wherein the tape accelerator includes a sulfonium cation having an aryl radical comprising a acetyloxy phenyl radical.
9. The corona shielding tape as claimed in claim 1 , wherein the tape accelerator comprises a superacid salt having the following chemical structure:
10. The corona shielding tape as claimed in claim 1 , wherein the polymer matrix comprises multiple polyvinyl-alcohols.
11. The corona shielding tape as claimed in claim 1 , wherein the polymer matrix comprises at least one polyvinylalcohol having crosslinked components.
12. The corona shielding tape as claimed in claim 1 , wherein the filler comprises at least one component selected from the group consisting of: carbon black, graphite, and carbon nanotubes.