Roebel bar for rotating electrical machines
View Patent ↗A Roebel bar for a rotating electrical machine includes a straight slot part disposed in a slot in an iron sheet of a stator of the rotating electrical machine and a bent yoke part adjacent to the straight slot part and protruding from the stator, wherein the bent yoke part is configured to connect the Roebel bar to at least one more Roebel bar so as to form a winding. A copper conductor disposed in the straight slot part and the bent yoke part is surrounded by an insulation having an outer surface. A slot corona shielding includes an electrically conductive layer disposed on the outer surface of the insulation in an area of the straight slot part. A yoke corona shielding includes a semiconducting layer disposed on the outer surface of the insulation in an area of the bent yoke part.
1. A Roebel bar for a rotating electrical machine comprising:
a straight slot part disposed in a slot in an iron sheet of a stator of the rotating electrical machine;
a bent yoke part adjacent to the straight slot part and protruding from the stator, wherein the bent yoke part is configured to connect the Roebel bar to at least one more Roebel bar so as to form a winding;
a copper conductor disposed in the straight slot part and the bent yoke part;
a first insulation surrounding the copper conductor and having an outer surface;
a slot corona shielding including an electrically conductive layer disposed on the outer surface of the first insulation in an area of the straight slot part;
a yoke corona shielding including a semiconducting layer disposed on the outer surface of the first insulation in an area of the bent yoke part; and
an element configured to lower a capacitive coupling disposed in a transitional region between the straight slot part and the bent yoke part so as to prevent excessive heating and discharges in the transitional region, the element including an additional second insulation disposed directly on the first insulation and extending along the transitional region.
2. The Roebel bar as recited in claim 1 , wherein a material of the first insulation differs from a material of the additional second insulation.
3. The Roebel bar as recited in claim 2 , wherein the materials of the first and second insulation each have a different insulating quality.
4. The Roebel bar as recited in claim 2 , wherein the first insulation includes resin-impregnated glass/mica strips, and wherein the additional second insulation includes at least one of resin-impregnated strips, wovens and nonwovens comprised of quartz glass.
5. The Roebel bar as recited in claim 2 , wherein the first insulation includes resin-impregnated glass/mica strips, and wherein additional second insulation includes at least one of resin-impregnated strips, wovens and nonwovens comprised of polymeric fibers.
6. The Roebel bar as recited in claim 4 , wherein the resin-impregnated strips, wovens and nonwovens include a resin with a low dielectric constant.
7. The Roebel bar as recited in claim 5 , wherein the resin-impregnated strips, wovens and nonwovens include a resin with a low dielectric constant.
8. The Roebel bar as recited in claim 2 , wherein the additional insulation includes polymers having a relative dielectric constant of between 2 and 4.
9. The Roebel, bar as recited in claim 8 , wherein the polymers are selected from the group consisting of: PTFE and PP.
10. The Roebel bar as recited in claim 8 , wherein the additional insulation is applied by one of shrink-fitting, spraying, immersion, adhesion, vulcanizing and pouring.