Three dimensional eddy current calculation with integral equation method for transformers

To calculate eddy current on multiply connected magnetic substances, the frequency domain volumetric integral method has been developed. This method requires no air space grid; therefore, it is suitable for complicatedly structured objects such as transformers. Verification tests using simple plates show good agreements with analytical solutions. Two application tests to transformers are presented. In the 1st test which examines the magnetic flux density in the clamping plate, the calculated results agree with the measured ones within 10 to 30%. In the 2nd test which compares the calculated eddy current density with the measured temperature rise on the clamping plate, their results agree for the distribution property. Te suitability of this method for eddy current evaluation in power transmission equipment is confirmed.