POLYPHASE EDDY-CURRENT TESTING

Polyphase eddy current testing is proposed. The operating principle of this system is as follows. The polyphase eddy current testing system may be regarded as one of the polyphase transformers. Primary balanced polyphase coils are star connected and secondary polyphase circuits a re composed of the target. When balanced polyphase currents are fed in to the primary coils, zero phase voltage is detected if the target has defects. No zero phase voltage is detected if the target has no defec ts. It is found that this method has a higher sensitivity compared wit h that of conventional eddy current testing.