C.S. Psomopoulos, C.G. Aronis, C.G. Karagiannopoulos, and P.D. Bourkas (Greece)
Electrical contacts, crossing resistance, shipyardsenvironmental conditions, digital measurements forevaluation, non linear conductivity.
In this work, an experimental investigation is attempted, concerning the effects of the shipyards' industries environment in the operation of electrical contacts. Analog to digital measurements were performed and physical interpretations of the dominant phenomena are presented. The experimental setup is in agreement with IEC0660 specifications concerning switch overheat tests. The specimens were installed in electrical panels near by piers and docks and had the following nominal characteristics: isolators 500V/250A, and relays 500V/250A. The measurements were performed through A/D converters with a sampling frequency of 50MHz. Waveforms of the voltage drop and current were obtained for the usual load values of the specimens. Current voltage plots (I-V plots) are also presented. Further analysis of the data obtained is performed and it is concluded that the interfacial layer determines the conduction mechanisms. In this case the contacts usually operate in advanced degradation (due to pollution and sea) thus the current conduction is mainly attributed to field emission or field ionisation processes. The above dominant effects characterize high rates of electronic conduction via stationary metal contacts at a state where linear behavior has ceased and instabilities are developed. The results lead to an effective evaluation test for contacts installed in shipyards and could aid in the maintenance procedures.
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