Here is a question that has been running around my head for a while:

Lets say you have an electrical installation that supplies 100V DC with a MAXIMUM current of 100A. No trip switch nothing, those are the only constraints.

Now, lets say an arc is created by holding two ends together for 1 nanosecond and then seperated. Lets assume that the cables have no resistance for simplicity sake. The arc is created through the ionization of the air between the ends as the ends are seperated (I presume). Lets say the arc is present for 1 nanosecond and after that point the distance seperating the two ends is too far to support the arc.

Question 1
What would the current and voltage be for the nanosecond when the arc jumps. I can only assume that the resistance of air would be negligible but what about the resistance of the plasma created which is the arc?

Question 2
Would this arc run through the circuit as a transient? (I suppose it would)

Question 3
Would a trip switch be able to react fast enough to catch the transient and to stop damage from occuring in the associated equipment?

Question 4
What would the ratings be of a suitable trip switch?

Question 5
Would the addition of MOV's on the power supplies of the equipment in the circuit help?

Question 6
Ok, now lets assume that the arc is held for 100ms. What would the effect be in terms of voltage and current?

Question 6a
What would the effect be on a trip switch?

Question 7
Would the arc jump in a vacuum?


Ok, I don't know the answers to any of this but I find it interesting to think about. The reason I started wondering about all of this is because my wife saw a youngster jump starting his mothers car. He kept touching the jumper leads together and making sparks. I thought that this was a really bad idea because I thought that it could blow the ECU due to the transients running through the circuits of the car. Ok, I must admit, I find wondering about such thing to be fascinating!