This guide discusses both on-line and off-line partial discharge (PD) measurements on complete windings of any type, as well as measurements on individual form-wound coils and bars. Measurements selected from those that are outlined may be appropriate for application during the manufacture, installation, operation, and maintenance of windings of ac rotating machinery. The purpose of this guide is to identify test methods that may be useful in the measurement of PD activity involving the electrical insulation systems of ac rotating machinery for quality control and to detect winding aging. New IEEE Standard - Superseded. A review of the nature of partial discharge in machine windings, how it can be measured under both off-line and on-line conditions, how it can be measured for individual form-wound coils or bars, and the significance and limitations of the measured values are covered.