Have a good day,

Let's consider a scenario where we have a single box, and the outer surface of this box is insulated with an insulation material. Imagine this box being inside an aircraft. As the altitude of the aircraft increases, how does the new breakdown voltage of this insulation material change? Is it possible to calculate this change?

Thank you.

 

The insulation property of air changes with altitude. Any break in the insulation and electricity can get out. I have never had a problem with insulation. Even a thin layer of paint stops the sparks. (experience not knowledge) I live at altitude and know of the problems with CRT-TVs.

 

As the altitude of the aircraft increases, how does the new breakdown voltage of this insulation material change? Is it possible to calculate this change?

This is what Bing's AI bot says:

"Electrical derating for altitude is necessary because altitude affects the heat dissipation capability of the heat sink and units in locations at 3300 ft (1000 m) above sea level must be derated. A common rule of thumb is a 2% derating for every 1000 ft above the 3300 ft altitude level. Dielectric strength is derated at a rate of approximately one percent per 100 m /1000m ASL. For elevations above 6562 ft (2000 m), the operational voltage (UN) should be derated according to Paschen’s Law1.

I hope that helps!

Learn more:
1. electriciantalk.com
2. cigreconference.ca
3. eng-tips.com
4. eaton.com
5. nepsi.com
+3 more"

I saw references to ANSI C37.30 and IEC/DIN DVE 0111 and the following table on eng-tips.com while searching:

                         Altitude Derating Factor
  Altitude:               Dielectric(pu)     Current (pu)
   >3,000 ft (1000 m)         1.00              1.00
    4,000 ft (1200 m)          0.98             0.992
    5,000 ft (1500 m)          0.95             0.980
   10,000 ft (3000 m)          0.80             0.96
   12,000 ft (3600 m)          0.75             0.95
   14,000 ft (4200 m)          0.70             0.935

 

It is the air, nothing more.

the thinner the air the lower breakdown

 

I don’t think he is talking about air.

Let's consider a scenario where we have a single box, and the outer surface of this box is insulated with an insulation material.

 

I don’t think he is talking about air.

Maybe I misunderstood, sorry. I'm asking for the systems inside the aircraft. For example, I'm asking for an epoxy or silicone coating on the surface of an avionic unit. I could not understand the connection between this change in the air condition and the insulating material (such as epoxy resin) used.

 

I could not understand the connection between this change in the air condition and the insulating material (such as epoxy resin) used.

What makes you think it does? I would agree with you that it does not make sense, but what do I know, perhaps air pressure has an effect on insulating materials.