Why rated current of an inverter decrease when working temperature increase?

Why rated current of an inverter decrease when working temperature increase?

The same reason it decreases at elevated altitudes.

Most electrical equipment is rated (ampacity or Kw) on the ability to keep it cool or more accurately its ability to shed waste heat. That is why if you look at conductor ratings in Natl Electric Code you will see a large difference between those in conduit and those in free air. Higher A M B I E N T temperatures reduce ability to shed waste heat therefore you must derate it to avoid burnout.

The reason higher altitude causes derate is the air is less dense and has less ability to transfer the heat from equipment.

Dan Bentler

Think of it this way, if you take a wire with insulation and start to heat it up what happens to the insulation? It melts off. The same type of thing holds true with electronics, the silicone, germanium and other materials used in making the internal items of the electronic components starts to break down as it gets hotter as well. So if you dont have the heat dissapation then your component is going to fail prematurely, hence derate for safety and longevity.