NONDESTRUCTIVE ULTRASONIC METHOD OF INSPECTION THE DEGRADATION DEGREE OF MATERIAL IN THE "FOOT" AREA OF THE CERAMIC INSULATOR OF C4-550-II TYPE DURING EXPLOITATION

An important engineering problem not solved yet in our country but appearing in literature is detection and monitoring changes in time the cracks arising and elongating in the ceramic material of the bottom part of insulator inside metal fittings. The ultrasonic method has been developed and equipped with ultrasonic transducers of special construction by authors of paper to investigate the insulator of C4-550-II type. The results of destructive mechanical strength tests of insulators obtained by control department of ZAPEL factory showed neither one an event destruction of the metal part of insulator, the all destruction events has occurred in ceramic part of insulator close to the bottom metal fittings. The presented method is based on the propagation properties of longitudinal and transversal ultrasonic waves in ceramic materials. The results of laboratory measurements carried out with use the SOFRATEST computer card of ultrasonic measurements for an insulator containing artificial defects in the form of cuttings starting from the bottom surface are presented in the paper. The method, the set of transducers and course of measuring knowledge is the subject of an offer The Physical Acoustics Department of The Institute of Fundamental Technological Research.

(Authors: F. Rejmund, P.Gutkiewicz, Z. Peski - 1999 year).
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Special paper prepared to present at "28th National Conference of Nondestructive Investigations", 28 Krajowa Konferencja Badan Nieniszczacych Zakopane'99, POLAND