Schneider MPPT Charger Question

[inetdog]

Their tech support person said it was due to thinner air having less resistance thus increasing the possibility of creepage. I would have thought that thinner air would have more resistance but I have not researched it. I'm OK with not using the 80-600 since the 60-150 are less than 1/2 the price and I am also looking at outback and they have an 80 amp version at 150 volts for 1/2 the price as well.

It seems a bit paradoxical, but the physics does indeed tell us that when staring around atmospheric pressure the voltage that a particular fixed gap can withstand does go down as the pressure decreases.
Eventually (but not on the earth's surface) you get to a low enough pressure that the voltage starts to rise again, getting to its highest overall value when you reach a vacuum.
The reason for this depends on the mean free path of an ionized air molecule moving under the voltage gradient and how many additional air molecules it will hit and ionize along the way. Lower pressure equals longer mean free path equals higher energy when it hits another molecule which means more ionization.

[SunEagle]

It seems a bit paradoxical, but the physics does indeed tell us that when staring around atmospheric pressure the voltage that a particular fixed gap can withstand does go down as the pressure decreases.
Eventually (but not on the earth's surface) you get to a low enough pressure that the voltage starts to rise again, getting to its highest overall value when you reach a vacuum.
The reason for this depends on the mean free path of an ionized air molecule moving under the voltage gradient and how many additional air molecules it will hit and ionize along the way. Lower pressure equals longer mean free path equals higher energy when it hits another molecule which means more ionization.

In layman's terms that sounds like a static shock would be bigger and travel farther at a higher altitude.

I know the rule of thumb for most electric arcs is ~ 1 inch per 1000 volts (in low humidity air) but that must change at higher altitudes.

[inetdog]

I know the rule of thumb for most electric arcs is ~ 1 inch per 1000 volts (in low humidity air) but that must change at higher altitudes.

Yup, the voltage per inch gets lower or the inches per kV gets higher. Take your choice of units.
It really makes a difference when designing aircraft and balloon instrumentation (or at least it did back in the tube days).

[bcroe]

Yup, the voltage per inch gets lower or the inches per kV gets higher. Take your choice of units.
It really makes a difference when designing aircraft and balloon instrumentation (or at least it did back in the tube days).

I thought the altitude limit was for cooling, not voltage. You designed with tubes? I used other peoples
tube designs, but all my design has been solid state. Bruce Roe

[inetdog]

I thought the altitude limit was for cooling, not voltage. You designed with tubes? I used other peoples
tube designs, but all my design has been solid state. Bruce Roe

Nope. I just played with radios, etc. But I followed tubes because they are so neat.

There was an interesting side alley as semiconductors were coming to the fore but were not at all radiation resistant.
The military was experimenting with what was essentially a tube integrated circuit for use in satellites.
Multiple arrays of plates and grids over a segmented heated cathode plate inside a combined vacuum and thermal envelope. They called them TIMMs, Thermally Integrated Micro Modules.
AFAIK nothing ever came of it because semiconductor technology improved fast enough instead.

Never had to do any designing with tubes except for CRTs, but I could have....