The Effect Of The Offline Distance On The Characteristics Of Arc Discharge Between The Pantograph And Catenary And The Friction And Wear Performances With Electric Current

Currently, with increasing speed of electric trains, the work conditions of the pantograph contact strip/contact wire system become worse and worse. On the one hand, the arc discharge between the pantograph and contact wire will have a serious impact on the quality of carrying-current of the pantograph-catenary system. Moreover, the service life of contact materials will decrease due to a poor friction and wear behavior with electric current, which results in a waste of resources; Therefore, it is significant to study friction and wear performances of the pantograph-catenary system with electric current. In the thesis, a block-on-ring carrying-current friction tester was used to investigate into the characteristic of arc discharge and the friction and wear performances and a series of tests are carried out. The conclusions can be drawn as follows:(1) In the experiment test, vibration of the contact strip is measured. It is found that an approximate sinusoidal vibration of the strip occurs continuously, but there is a small difference among the vibration amplitudes of different test cycles. The average offline distance increases with increasing speed and decreasing normal load; The arc discharge power increase and then decrease with increasing average offline distance, and the arc striking distance is 216μm and the arc extinguishing distance is 445μm in the case of input voltage 9V; Spark discharge is the most common when the offline distance is small, and then the short arc discharge and long arc discharge become a main discharge form with increasing offline distance. But short arc discharge occurs more frequently when the offline distance is large enough; The single arc discharge energy and the discharge time per kilometer both increase rapidly and then become stable with the increase of offline distance, and both reach the maximum when the offline distance is close to 500μm.(2) The pure carbon strips and metal-impregnated carbon strips are used to investigate into the friction and wear performances with electric current and the test results show that their friction and wear performances are different. Under the same test conditions, the offline distance of the pure carbon strip is always bigger than that of the metal impregnated carbon. Test materials have a smaller impact on the wear performances than the normal force does; The wear rates of the pure carbon and metal-impregnated carbon increase with the increase of test time. The wear rates firstly increase and then decrease with increasing average offline distance. The wear resistance of the metal impregnated carbon strip is better than that of the pure carbon strip; The friction coefficient of the pure two strip decreases with the increases of offline distance and test time. The friction coefficient of the metal-impregnated carbon is smaller than that of the pure carbon strip under the same test conditions. The arc discharge energy in an unit time of two strips increases slowly with the increase of test time, but it increases rapidly and then decreases slowly with increasing average offline distance. The pure carbon strip easily creates arc discharge; The arc erosions of two strips are aggravated with increasing offline distance. When the offline distance is large enough, the arc erosions are weakened. Erosion pits, thermal stress cracks and debris falling are main arc erosion mechanisms of the pure carbon strip. Meanwhile, a large number of spalling layers, pittings and furrows can be observed on the worn surface of the metal-impregnated carbon strip.(3) The arc discharge and wear behaviors of the pure carbon strip have a marked change with the change of input current and voltage. The wear rate of strip increases rapidly with the increase of input current and voltage, but it increases slowly with increasing sliding speed; The friction coefficient of the pure carbon strip decreases obviously with the increase of input current and voltage. However, it decreases at a relatively steady rate with increasing sliding speed; The arc discharge form will change when the arc energy is different. the larger the arc energy, the more serious the arc discharge.