The present invention relates to a multilayer laminate comprising at least three layers, wherein the two outer layers are each nonwoven backing sheet (7) containing a crystalline silicate mineral powder impregnated with a coating of an impregnating resin based on acrylate derivatives, which is suitable for increasing the compactness of the insulating sheet and for preventing the silicate mineral powder from detaching from the aramid fiber during use; the multilayer laminate having an inner layer being free of crystalline silicate mineral powder that comprises either i) heat resistant floc and binder, or ii) heat resistant polymeric film. The impregnating resin also comprises an organic solvent, which is capable of reducing the viscosity thereof and of promoting its deep penetration into the sheet. In addition, the impregnating resin comprises a UV polymerization photoinitiator which is suitable for curing the resin, only after said resin has been applied to the sheet and has penetrated deeply therein. The invention also describes the method for impregnating the insulating sheets.

An insulating system having improved partial discharge resistance includes an insulating tape around a conductor. The tape is a mica tape joined to a carrier. The tape is impregnated with a synthetic resin, and is interspersed with a nanoparticulate filler, present bimodally, in the form of two fractions of the filler differing in particle size and fraction size. An adhesion promoter may be in the resin.

An insulating system having improved partial discharge resistance includes an insulating tape around a conductor. The tape is a mica tape joined to a carrier. The tape is impregnated with a synthetic resin, and is interspersed with a nanoparticulate filler, present bimodally, in the form of two fractions of the filler differing in particle size and fraction size. An adhesion promoter may be in the resin.

An electrical insulating system and an associated insulated stator bar are provided. The electrical insulating system includes an electrically insulating mica paper and a fiber glass disposed on a first surface of the electrically insulating mica paper. The electrically insulating mica paper and the fiber glass are impregnated with a curable binder resin composition. The curable binder resin composition includes about 21 weight percent to about 73 weight percent of a solid or semi-solid epoxy resin having an epoxide functionality of about 2.5, about 0.8 weight percent to about 49 weight percent of a liquid epoxy resin having an epoxide functionality of about 2, about 4 weight percent to about 15 weight percent of a bisphenol A-formaldehyde novolac, a metal acetylacetonate catalyst, and about 2.5 weight percent to about 15 weight percent of a toughener selected from the group consisting of polyethersulfone, methylmethacrylate butadiene styrene, and a combination thereof.

An electrical insulating system and an associated insulated stator bar are provided. The electrical insulating system includes an electrically insulating mica paper and a fiber glass disposed on a first surface of the electrically insulating mica paper. The electrically insulating mica paper and the fiber glass are impregnated with a curable binder resin composition. The curable binder resin composition includes about 21 weight percent to about 73 weight percent of a solid or semi-solid epoxy resin having an epoxide functionality of about 2.5, about 0.8 weight percent to about 49 weight percent of a liquid epoxy resin having an epoxide functionality of about 2, about 4 weight percent to about 15 weight percent of a bisphenol A-formaldehyde novolac, a metal acetylacetonate catalyst, and about 2.5 weight percent to about 15 weight percent of a toughener selected from the group consisting of polyethersulfone, methylmethacrylate butadiene styrene, and a combination thereof.

A coil for a rotary electrical machine comprising a coil conductor and an insulation layer disposed around an outer periphery of the coil conductor, the insulation layer comprising a cured product of a mica tape, the mica tape comprising mica, a reinforcing member and a thermosetting resin, and having a reaction heat generated by a curing reaction of the thermosetting resin, as measured by differential scanning calorimetry (DSC), of 270 J/g or less.

A method is disclosed of applying a mica paper around an electrical conductor, the process including attaching the tape comprising the mica paper to the conductor at an attachment point on the conductor; winding the tape around the conductor surface until the tape has been wound to a point that is at least 25 percent of the conductor circumference from the attachment point and then initiating a continuous removal of the support layer from the tape, starting at the attachment point; the mica paper remaining in contact with the surface of the conductor; and continuing to wind the tape around the conductor while simultaneously removing the support layer at a removal point until a desired amount of conductor surface is completely covered with at least one layer of the mica paper, with the proviso that the removal point is maintained at least 25 percent of the conductor circumference behind the winding point until the desired amount of conductor surface is completely covered. A tape is also disclosed of mica paper and a support layer, wherein the mica paper; wherein the initial elongation of the support layer is equal to or less than the initial elongation of the mica paper; and wherein the support layer is demountably attached to the mica paper such that when a delamination force of 10 N/10 mm or less is imposed on the support layer it can be separated from the mica paper.

A method is disclosed of applying a mica paper around an electrical conductor, the process including attaching the tape comprising the mica paper to the conductor at an attachment point on the conductor; winding the tape around the conductor surface until the tape has been wound to a point that is at least 25 percent of the conductor circumference from the attachment point and then initiating a continuous removal of the support layer from the tape, starting at the attachment point; the mica paper remaining in contact with the surface of the conductor; and continuing to wind the tape around the conductor while simultaneously removing the support layer at a removal point until a desired amount of conductor surface is completely covered with at least one layer of the mica paper, with the proviso that the removal point is maintained at least 25 percent of the conductor circumference behind the winding point until the desired amount of conductor surface is completely covered. A tape is also disclosed of mica paper and a support layer, wherein the mica paper; wherein the initial elongation of the support layer is equal to or less than the initial elongation of the mica paper; and wherein the support layer is demountably attached to the mica paper such that when a delamination force of 10 N/10 mm or less is imposed on the support layer it can be separated from the mica paper.

Tape adhesives suitable for impregnating processes for insulation systems are described. Embodiments of the tape adhesives include solid insulation material such as mica, anhydride-free impregnating resins and accelerators for the anhydride-free impregnating resins. The tape adhesives may be adjusted with respect to the reactivity of the accelerators for the anhydride-free impregnating resins in relation for the storage stability of the overall insulation systems.

Tape adhesives suitable for impregnating processes for insulation systems are described. Embodiments of the tape adhesives include solid insulation material such as mica, anhydride-free impregnating resins and accelerators for the anhydride-free impregnating resins. The tape adhesives may be adjusted with respect to the reactivity of the accelerators for the anhydride-free impregnating resins in relation for the storage stability of the overall insulation systems.