Magnet core

A method for production of a magnet core comprising a relative permeability μ that is greater than 500 and less than 15,000, a saturation magnetostriction λs whose amount is less than 15 ppm and consisting of a ferromagnetic alloy in which at least 50% of the alloy consists of fine crystalline particles with an average particle size of 100 nm or less and is characterized by the formula FeaCobNicCudMeSifBgXh in which M is at least one of the elements from the group consisting of V, Nb, Ta, Ti, Mo, W, Zr, Cr, Mn and Hf,

• a, b, c, d, e, f, g are stated in atom %,
• X denotes the elements P, Ge, C as well as commercial dopants and a, b, c, d, e, f, g, h satisfy the following conditions:
• 0≦b≦40;
• 2<c<20;
• 0.5≦d≦2;
• 1≦e≦6;
• 6.5≦f≦18;
• 5≦g≦14;
• h<5 atom %
• with 5≦b+c≦45, in which a+b+c+d+e+f=100, the method comprising the step of performing a heat treatment in a magnetic transverse field of the magnet core.

A current transformer for alternating power with a magnet core comprising a relative permeability μ that is greater than 500 and less than 15,000, a saturation magnetostriction λs whose amount is less than 15 ppm and consisting of a ferromagnetic alloy in which at least 50% of the alloy consists of fine crystalline particles with an average particle size of 100 nm or less and is characterized by the formula FeaCobNicCudMeSifBgXh in which M is at least one of the elements from the group consisting of V, Nb, Ta, Ti, Mo, W, Zr, Cr, Mn and Hf,

• a, b, c, d, e, f, g are stated in atom %,
• X denotes the elements P, Ge, C as well as commercial dopants and a, b, c, d, e, f, g, h satisfy the following conditions:
• 0≦b≦40;
• 2<c<20;
• 0.5≦d≦2;
• 1≦e≦6;
• 6.5≦f≦18;
• 5≦g≦14;
• h<5 atom %
• with 5≦b+c≦45, in which a+b+c+d+e+f=100,
• wherein the current transformer, in addition to the magnetic core as transformer core, has a primary winding and at least one secondary winding, wherein the secondary winding is low-resistance terminated by a load resistance and/or measurement electronics.