The discussion revolves around the phenomenon of sparks occurring at the connections of electric trains, particularly focusing on the interaction between the train's pantograph and the overhead wires or third rail. Participants are exploring the underlying reasons for these sparks, including potential voltage fluctuations and contact loss.
The discussion is ongoing, with participants offering insights into the technical aspects of the problem. There is a recognition of the complexity of the terms used, and some participants are seeking clarification while contributing their own interpretations of the phenomena involved.
There appears to be some confusion regarding technical terminology, which may affect the clarity of the discussion. Participants are also considering the implications of environmental factors, such as the presence of air versus a vacuum, on the occurrence of sparks.
Are you talking about the sparks between the train's pantograph pickup and the overhead energized wire catenary, and the sparks that occur between an energized third rail and the contact pickups on the train? If so, these sparks occur only occasionaly at areas where full contact between the wires or energized rail is momentarily lost. Based on this momentary loss of contact, can you explain why sparks might occur in this situation?Kolahal Bhattacharya said:Homework Statement
When an electric train runs,we are familiar to the sparks at the end of cable connections.Why does it occur?Is it due to voltage fluctuations?
Homework Equations
The Attempt at a Solution
It's not the induced voltage that causes the spark. There is a large potential difference in emf between ther enegized wire and contact that has been de-energized during the momentary loss of contact. . Air, normally a very good insulator, lies between those 2 points. It is a very thin layer. What happens that causes the spark (arc)? Note: if this train was riding in a vacuum, there would be no spark.Kolahal Bhattacharya said:I cannot really understood your technical terms...However,I hope you are talking about the same problem.I should say the structure is like a wire over a structure like < whose base is attached to the train.
Well,what I suppose,during the momentary cut of contact,the back emf=-LdI/dt is high which desparately tries to retain the connection.So,a spark is seen.