“PARTIAL-DISCHARGE and POLARIZATION-DEPOLARIZATION CURRENT measurement for insulation condition testing of high voltage rotating machines” was the name of the lecture to which the VDE–student-club invited students and university staff on 14.11.2019.
Professor Dr. Norasage Pattanadech is currently a visiting professor at the Institute of Energy and High Voltage at the FHWS. During his visit Prof. Dr. Pattanadech agreed to contribute a lecture to the VDE lecture series. He informed the students about his daily work at King Mongkut's Institute of Technology Ladkrabang in Bangkok, Thailand.
In his laboratory for Dielectric Analytika of the Faculty of Engineering he mainly deals with Partial-Discharge (PD) and the Polarization-Depolarization-Current(PDC) measurement of high voltage rotating machines (up to 50 MV operating voltage). Besides, diagnostic testing and analysis of other kinds of high voltage equipment, i.e. transformers, underground cables, GISs, GILs, Insulators and so on are in his research field.
In his lecture, Prof. Dr. Pattanadech explains that 41 billion dollars of damage are caused by failed electric generator. 27% of the failures can be attributed to insulation problems in the insulator winding. Most insulation problems can be traced back to a thermal or electrical load. Early diagnostics and quality testing play a major role in the life cycle of high voltage rotating machines. Therefore, the main focus of Prof. Dr. Pattanadech's work is in this area. In his laboratory Mr. Pattanadech examines the motors for their conductivity, permeability, dissipation factor and for partial discharges. For the investigations of conductivity, permeability, dissipation factor, the PDC-method is used. This method is a step response measurement in the time domain in which the material is loaded with voltage and the resulting current is evaluated. Prof. Pattanadech discussed his investigations, which carried out directly on the individual motor windings. Partial discharges can occur if there are defects in the material, e.g. air inclusions in the insulating material. If partial discharges are present in the insulation material of the winding, this means that in most cases the motor may lead to failure finally. Prof. Pattanadech therefore explained how PD can be recognized according to the IEC standards.
At the end of the presentation Prof. Dr. Zink, head of IEHT and branch manager of VDE, thanked Mr. Pattanadech for the presentation. Prof. Dr. Zink also thanked the countless listeners for the appearance and expressed his support for the common ground between the IEHT and Prof. Pattanadech.
Fabian Dax, Julius Händel
