This article is based on the author＇s experience, since 1984, of the application of the EL CID test, mainly on salient-pole hydroelectric generators. After giving an introduction to the EL CID theory, the basic setting up procedure for the test is indicated. The article then provides a review of the detailed analysis, applied to a variety of initially anomalous phenomena encountered in results from SO or more such tests, by which the technique is shown to be a reliable diagnostic tool. This leads to a brief statement of the recommended test procedure.