A wire testing method and apparatus test wire in-situ in a rigidly installed state, such as an aircraft. An apparatus for rapidly switching the excitation voltage and ground compensates for stray currents. The apparatus outputs a stray current signal, a detected signal, and a difference signal indicative...http://www.google.com.hk/patents/US6812712?utm_source=gb-gplus-share專利 US6812712 - Wire test method and apparatus
