Patent ID: 7837807

Claim:
A magnetic core for current transformer, which the composition is represented by the general formula: Fe 100-x-z Ni x X′ z (atomic %), wherein X′ is at least one element selected from Si and B, and x and z comprises an amorphous alloy which is the composition of 5≦x≦30 and 14≦z≦30, respectively, a magnetic flux density B 8000 in 8000 Am −1 of said amorphous alloy is more than 1.2 T, an anisotropy field H K is in the range of more than 150 Am −1 and less than or equal to 1200 Am −1 , a squareness ratio B r B 8000 −1 is less than or equal to 5%, an alternate relative initial magnetic permeability μ r is in the range of more than 1000 and less than or equal to 4500 at 50 Hz and 0.05 Am −1 , and a μ ra100 /μ ra005 ratio of an alternate relative initial magnetic permeability μ ra100 of the amorphous alloy at 50 Hz and 100 Am −1 to an alternate relative initial magnetic permeability μ ra005 is in the range of 0.85≦μ ra100 /μ ra005 ≦1.15.