This guide is applicable to the detection and location of sources of acoustic emissions (AEs) from partial discharges (PDs) and other sources in power transformers and power reactors. There are descriptions of acoustic instrumentation@ test procedures@ and interpretation of results. Purpose This guide is intended to provide information that may be helpful in planning@ installing@ and operating acoustic measuring equipment and in meaningful interpretation of resulting data. Safety warning The safety warnings in this subclause apply only to work done on transformers installed in the field@ not to factory testing. Refer to factory test codes for safety warnings for these situations. Partial discharge (PD)