Study on Generation Mechanism of Radio-Wave Noise in High Speed Sliding-Contacts and Reduction Method

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In preserving the electromagnetic environment along railways it is important to reduce the levels of electromagnetic noises caused by the discontact phenomenon between the pantograph and trolley wire. However no effective measures for the noise reduction have been available at the present time because of the complexities of the discontact phenomenon. If this phenomenon could be elucidated using the sliding-contacts which is well-known as an experimental model of the pantograph current-collection system, it is possible to find out drastic means for suppressing the radio-frequency noises. In this study the discontact parameters were introduced for quantifying the occurrence situations of the mechanical discontact and electrical discharge appearing in the sliding-contacts, and through statistical measurements of these parameters attempt was made to elucidate the complex discontact phenomenon. The following results were obtained : As for the discontact parameters both the occurrence time-r … More ates of the discontact and discharge were used and simultaneous measurements of the above parameters were conducted using the brass sliding-contacts and the newly developed equipment with a personal computer. As a result it was found that both the discontact and discharge rates fluctuate approximately according to the normal probability distributions and when the sliding-speed and contact load are kept constant the discontact rate decreases with increasing the contact current, while the discharge rates increase, and also that the sum of the occurrence time-rates of the discontacts and discharges does not depend upon the contact current and this value unexpectedly agrees with the mechanical discontact rate without the contact current. Among the above results the inherent relationship holding between the discontact and discharge rates was also confirmed in the carbon sliding-contacts. It was, therefore, concluded that the discontact phenomenon can be quantified by the inherent properties described above. At present measurements of the occurrence frequencies of the discontact and discharge are conducted for investigating the properties peculiar to the sliding-contacts. Less