Effect of Atmosphere Change on Contact Voltage Drop at Sliding Contact

Takahiro UENO  Koichiro SAWA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E85-C    No.7    pp.1478-1485
Publication Date: 2002/07/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electromechanical Devices and Components
Keyword: 
oxide film,  contact voltage drop,  low atmospheric pressure,  physical adsorption,  

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Summary: 
The surface film of a slip ring is important for the sliding contact phenomenon. The surface film is affected by atmospheric temperature, humidity and air pressure. The main objective of our study is to examine the effect of oxygen gas on the sliding contact phenomenon. In the present experiment, we examined the contact voltage drop for continuous sliding when the atmosphere is changed from low pressure to atmospheric pressure by introducing oxygen (O2 20%+N2 80%) or nitrogen gas. As a result, the contact voltage drop increases rapidly with increasing gas pressure, and its fluctuation also becomes large. These phenomena are observed in both cases of oxygen (O2 20%+N2 80%) and nitrogen introduction. The results clearly show that the sudden increase of contact voltage drop is affected by factors other than the oxide film. Actually, the oxide film is not formed in the nitrogen atmosphere. Furthermore, the frictional coefficient of carbon and copper ring is changed at ambient atmosphere. It is inferred from these data that the contact voltage drop may be affected by the frictional coefficient. When the gas pressure decreases again, the contact voltage drop does not suffer from the effect of ambient gas. Therefore, only the resistance of the oxide film appears to affect contact voltage drop. In this paper, the effect of sliding contact phenomenon on the contact voltage drop by gas adsorption and film generation was examined.