Design Method of Coil System Generating Uniform Magnetic Field for Evaluating Anti-magnetic

It is confirmed the commercial frequency magnetic field over 5 mT affects to some current sensors. The way to give current sensors immunity from the magnetic field required if when a problem revealed. The magnetic shield will be suitable for that use, such simple method to give current sensors immunity should be considerable. For evaluating shields, the spatially uniform magnetic field is needed, which is large enough to put magnetic shield in, also bigger magnetic flux density than 5 mT. The design method of the coil which fulfilled those requirements was considered, and we produced a box-shaped coil 25 cm on a side to generate uniform magnetic field over 5 mT. It can generate 6.09 mT with DC and 3.40 mT with commercial frequency, and it will enclose 60 % of the volume of the magnetic shield with uniform field which has 1 % deviation from center.