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New ultrasonic equipment for non-destructive diagnostics of ceramic insulators in place of exploitation

Ranachowski P., Rejmund F., Zienkiewicz B.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

2004

Vol. 40, nr 15

169-176

The paper presents designed and experienced in IFTR PAS apparatus - acoustic instrument for materials parameters investigation of special assignment. The presented set-up is mainly expected to serve for ultrasonic measurements of long-rod insulators in use on site. The main object of research are insulators after long period of exploitation, showing high degree of material ageing process advancement. Diagnostics of such elements requires definite parameters of work of a sending-receiving unit, piezoelectric transducers of special construction, elaboration of proper methodology of ultrasonic measurements along with criteria of the object classification. Presented equipment is the result of many years experience of non-destructive acoustic research of long-rod ceramic insulators. This equipment was specially adopted for the field tests on the overhead lines and stations. The composition of the set-up, principle of its work and the calibration procedure with standardized blocks were described. The measurements of post insulator SWZPAK-110 type from 1976 year illustrate possibilities of application of the set-up. A microscopic structural analysis was used as comparative method. Correlation between the microstructure of the porcelain and parameters of ultrasonic wave propagation was established. The investigation proved possibility to employ the apparatus for diagnostic measurements of the polymer and hybrid insulators.

Acoustical distortions in capacitance hydrophones and the effect of diaphragms in measurements of shock wave pulses

Filipczyński L., Etienne J., Kujawska T., Wójcik J., Zienkiewicz B.

Archives of Acoustics

1998

Vol. 23, no. 2

251-266

The shock wave pulse measured by means of a membrane PVDF hydrophone was compared with the pulse obtained by means of the capacitance hydrophone showing distortions in the pulse trailing edge. The mechanism of distortions in the capacitance hydrophone was explained and confirmed by experiments as caused by transverse waves generated on the surface of the hydrophone's metal plate by compressional incident waves. The effect of the rise time of the measured shock wave pulses was interpreted and analysed by means of diaphragms with various apertures. Interaction of the applied diaphragms with the measured acoustic fields was explained showing their equivalence to the high pass filtering. The differentiating circuit used for determination of the particle velocity from the displacement, measured by the capacitance hydrophone, was analysed. Also an improved capacitance hydrophone was applied in measurements.