High voltage spark types.

[firewalker]

Can someone tell me the difference to the to high voltage sparks bellow? The first one is a thin blueish with the distinct sound spark. The second one is thick, orange with a hissing sound.



Is it just current difference? It is from an old smps for neon tubes. It has a switch that changes the spark. I couldn't find infos for this device (two step dimmer?).

Alexander.

[IanB]

A spark is a low resistance short circuit. The ordinary "spark" that you see, for example from an ignition coil, is starved of current and so the spark goes out immediately after it starts. If you make lots of such sparks one after the other you get a clicking or buzzing sound, which is the sound of lots of sparks close together with gaps in between. On the other hand, if the electrical supply does not run out of current once the spark starts then the spark turns into an arc, a continuous hot conductive path for electricity to flow through (like an arc welder, for instance). Such a continuous arc makes a sound similar to a flame.

In every practical application of arcs the supply is current limited. This is important, since as noted above an arc is a short circuit. If you create an arc in a circuit where the power supply has no effective current limiting (for instance a grid utility power system) then the current will be enormous and an explosion may occur.

[firewalker]

Thanks you. Someone asked me and I just wanted to make sure.

Alexander.

[Moseven]

Another example is the gas lighters without battery. They have a piezo, and by applying pressure, the voltage increases until a spark happens. That is a thin blue spark. Something else is a transformer of 20kV for Neon lights. That has more power, and it can make a buzzing glowing stable arc. There is a lot of energy in that arc. An electric welder uses that arc to melt metals.

[HighVoltage]

It seems to me, the difference is in spark time duration.

The first part of the spark has a duration of a few ms, then turns off and the spark channel breaks down and then it turns on again with a new spark. This is repeated by the frequency we hear, like 50 to 100 Hz, I would guess.

The second part of the spark has a much longer spark duration and the spark is sustained and stays on all the time.