An enamelled wire for a winding of an electric motor, including: an electrical conductor, and an electrical insulation system surrounding the electrical conductor, the electrical insulation system including a first electrical insulation layer including a first polymer and surrounding the electrical conductor, and a second electrical insulation layer surrounding the first electrical insulation layer, wherein the second electrical insulation layer includes a second polymer and a filler material dispersed in the second polymer, the filler material consisting of: A) graphene oxide, or B) graphene oxide and a first metal oxide, or C) graphene oxide, the first metal oxide, and a second metal oxide, or D) graphene oxide and the second metal oxide, wherein the filler material is present in an amount of 5-40% of the volume of the second electrical insulation layer.

Provided is a polyimide precursor including a polyimide precursor obtained by a reaction between a diamine compound and a tetracarboxylic dianhydride compound, in which the diamine compound contains at least one type selected from the group consisting of an aromatic diamine and an alicyclic diamine, the tetracarboxylic dianhydride compound contains at least one type selected from the group consisting of an aromatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride, and the total amount of the alicyclic diamine and the alicyclic tetracarboxylic dianhydride is 5.0 mol % or more and 70.0 mol % or less with respect to the total amount of constituent monomers of the polyimide precursor.

Provided is a polyimide precursor including a polyimide precursor obtained by a reaction between a diamine compound and a tetracarboxylic dianhydride compound, in which the diamine compound contains at least one type selected from the group consisting of an aromatic diamine and an alicyclic diamine, the tetracarboxylic dianhydride compound contains at least one type selected from the group consisting of an aromatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride, and the total amount of the alicyclic diamine and the alicyclic tetracarboxylic dianhydride is 5.0 mol % or more and 70.0 mol % or less with respect to the total amount of constituent monomers of the polyimide precursor.