Noise Diagnostics of Insulating Materials for Operation at High Temperature

Noise Diagnostics of Insulating Materials for Operation at High Temperature

Stať ve sborníku v databázi WoS či Scopus

The samples of insulation materials for operation at temperatures to 350 oC were tested in a high electric field. Tested materials covered with metal electrodes on both sides represent a parallel plate capacitor. The VA characteristics are proportional to U^n where n ~ 1. Partial discharges have an impact on conductivity at a high electric field and they are important sources of noise and acoustic emission signals. This phenomenon is related to the sample homogeneity and may be used for technology assessment and quality testing. The electromagnetic signal precedes the acoustic emission response and the time delay corresponds to the difference of propagation velocities of sound and electromagnetic radiation in the sample. This phenomenon may be used for the localization of voids in an insulator. A current pulse generated by a random discharge in a void within the insulator is represented by an exponentially decreasing function, whereas the acoustic signal exhibits a quasiperiodic damped behavior. Statistic characteristics of the impulse amplitudes of acoustic emission and partial discharges and their correlation are studied. The characteristics of studied materials depend on temperature and applied voltage. The methodology presented above serves for a non-destructive evaluation of insulators for power apparatuses working at high temperatures and at high voltages.

The samples of insulation materials for operation at temperatures to 350 oC were tested in a high electric field. Tested materials covered with metal electrodes on both sides represent a parallel plate capacitor. The VA characteristics are proportional to U^n where n ~ 1. Partial discharges have an impact on conductivity at a high electric field and they are important sources of noise and acoustic emission signals. This phenomenon is related to the sample homogeneity and may be used for technology assessment and quality testing. The electromagnetic signal precedes the acoustic emission response and the time delay corresponds to the difference of propagation velocities of sound and electromagnetic radiation in the sample. This phenomenon may be used for the localization of voids in an insulator. A current pulse generated by a random discharge in a void within the insulator is represented by an exponentially decreasing function, whereas the acoustic signal exhibits a quasiperiodic damped behavior. Statistic characteristics of the impulse amplitudes of acoustic emission and partial discharges and their correlation are studied. The characteristics of studied materials depend on temperature and applied voltage. The methodology presented above serves for a non-destructive evaluation of insulators for power apparatuses working at high temperatures and at high voltages.

Noise, Insulating materials, MIM systems, Partial discharges, Acoustic emission

KOKTAVÝ, P., ŠIKULA, J., KOKTAVÝ, B., LIEDERMANN, K.

22.10.2001

University of Florida, Gainesville, Florida, USA

Gainesville, Florida, USA

981-02-4677-3

Proceedings of ICNF 2001

759

4