Surge protection in industrial enclosures

It's yer actual oscillation wot does it. The bit I did glean was this: In addition to keeping connecting leads short


This is really a feature of when things change quickly compared to the length -  In normal electrical theory we assume that when something is at XX volts it has reached equilibrium and we neglect the time it takes for the electric effect of doing something to get from one end to the other.

The speed limit for signals on a wire is a bit less than the speed of light (300m per microsecond for light, more like 200m per microsecond in typical cables)  (this is a law of physics, not the traffic cop kind of law...)

Much as there is very little slope in the level on the surface of a slow moving canal, water finding its own levels and all that, but in a fast flowing river in flood or at the moment you lift a sluice gate there may be all sorts of gradients, eddies, swirls and ripples, when things speed up, the assumption that everything  has reached a steady state level is not really true.

The one dimensional problem of electrons being passed from atom to atom along a wire has something in common with the newtons cradle suspended balls toy, in that shocks 'reverberate' along the transmission like for a few cycles and sometimes, if you are unlucky with your lengths your kickback may be out of phase with what you put in, and a double amplitude peak occurs.

A surge arrestor firing is rather like sneaking a brick wall in next to the last ball in the chain between swings - it does not stop the current flow as such and so does not absorb the energy, it forces the voltage down, but the current is then very high so abruptly altering the current to voltage ratio on the line.

Mike.

It's yer actual oscillation wot does it. The bit I did glean was this: In addition to keeping connecting leads short


This is really a feature of when things change quickly compared to the length -  In normal electrical theory we assume that when something is at XX volts it has reached equilibrium and we neglect the time it takes for the electric effect of doing something to get from one end to the other.

The speed limit for signals on a wire is a bit less than the speed of light (300m per microsecond for light, more like 200m per microsecond in typical cables)  (this is a law of physics, not the traffic cop kind of law...)

Much as there is very little slope in the level on the surface of a slow moving canal, water finding its own levels and all that, but in a fast flowing river in flood or at the moment you lift a sluice gate there may be all sorts of gradients, eddies, swirls and ripples, when things speed up, the assumption that everything  has reached a steady state level is not really true.

The one dimensional problem of electrons being passed from atom to atom along a wire has something in common with the newtons cradle suspended balls toy, in that shocks 'reverberate' along the transmission like for a few cycles and sometimes, if you are unlucky with your lengths your kickback may be out of phase with what you put in, and a double amplitude peak occurs.

A surge arrestor firing is rather like sneaking a brick wall in next to the last ball in the chain between swings - it does not stop the current flow as such and so does not absorb the energy, it forces the voltage down, but the current is then very high so abruptly altering the current to voltage ratio on the line.

Mike.