Factory Acceptance Tests: A Comparative Analysis to Establish a Baseline for Testing Data

Abstract

Factory acceptances tests (FATs) of a new high-voltage (HV) rotating machine include comprehensive diagnostic tests of the finished stator winding insulation system. From these tests, the end user obtains the baseline data for the condition monitoring performed during the machine?s operating life. The design geometry of the stator windings and manufacturing processes used to produce them will affect the dielectric test results. There is a significant challenge in comparing the test results from different stators to obtain a statistically useful sample for an acceptance test database. This article compares the dielectric test results from the 14.4-kV windings of several new 1,800-r/min, 26.1-MW (35,000-hp) centrifugal compressor synchronous motor stators of identical design, built for two U.S. chemical plants. The results are compared with those from accompanying sacrificial coils. The stator diagnostic tests include the dissipation factor (DF) or tan delta, power factor tip up (PFTU) or delta tan delta, offline partial discharge (PD), corona inspection with an ultraviolet (UV) analyzer, and online PD. Sacrificial coils produced and processed alongside each stator receive the specified American Petroleum Institute (API) coil acceptance tests and corona inspection with a UV analyzer. The PD measurements on the sample coils were repeated at an elevated voltage, and the results were compared with the corona inspection observations. This article shares the comparative analysis of the stator and coil test results as an excellent example of the baseline FAT data.