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- DMA (1)
- Early shrinkage of cement paste (1)
- Fibre optic sensors (1)
- Material characterisation (1)
- Materials behavior (1)
- Mechanical properties (1)
- Monitoring (1)
- Partial discharge (1)
- Solid dielectric (1)
- Ultrasonic spectroscopy (1)
Eingeladener Vortrag
- nein (2)
For prediction of wave propagation in multilayered structures it is necessary to know the material properties. Important parameters are sound velocity (c) and attenuation ( ). Values found in the literature were not satisfactory mainly due to insufficient accuracy of measured attenuation. Experiments were carried out in Division VI.3 - Durability of Polymers. The ultrasonic test equipment was provided by Divisions VIII.1 - Measurement and Testing Technology; Sensors and VIII.4 - Acoustical and Electromagnetical Methods.
Acoustic emission (AE) sources caused by partial discharges in solid dielectric devices like transition joints or outdoor terminations are investigated. Together with a prepared high voltage cable end this device forms a multilayer structure. The hypothesis is that due to the high damping of polymeric insulation materials no AE signal can be detected on the surface of the prescribed structures. An analytical technique is used to determine the transmission for a typical multilayer insulation. For quantitative computations it is necessary to know the material properties such as complex Young´s modulus, density and the Poisson´s ratio. Since the properties found in the literature were not fully satisfactory, measurements had to be done. The experimental setup and the results are shortly presented. Finally it will be shown that the transmission path plays not the significant role as was assumed in the beginning.
Fibre-optic sensors for early damage detection in plastic insulations of high-voltage facilities
(2011)
Fibre-optic sensors (FOS) have great potential as online damage detectors when integrated in HV accessories. Among their well-known use as temperature and strain sensors, there are some more opportunities of use, e. g. they can intimately be embedded in polymeric insulations of HV cable terminations and joints to detect and monitor partial discharges right at the location of their origin. Two FOS types for early PD detection were investigated: an embeddable fibre-optic acoustic sensor to measure acoustlc waves in polymeric insulations generated by PDs, and a fluorescent optical fibre to detect first optical effects during ionization processes in the insulation material. The paper descrlbes these methods, related monitoring Problems and shows first test results.