Dear Salah,

I hope I understood your question as you wanted it to be recognized.

Numerous factors can ruin power electronic components. First let us eliminate mishandling - a major factor during assembly.

External factors to be considered include:

Solar load - often seen in hot environments when devices are subject to solar radiation leading to unexpected thermal burden regarding ambient temperature.

Cosmic radiation - a statistical failure depending on geographic position

Short circuit due to damage to external wires - happens quite often

Degradation of heat sinks due to dust - very common

Hazardous gases like SO2 in industrial environments - depending on location

Humidity as in tropical environments

Vandalism, sabotage or mechanical impacts like fork lifters hitting a cabinet (no kidding)

Voltage sags with quickly returning voltage that damages rectifier diodes due to high surge currents -  very common in weak grids like India and China

Lightning Strikes - happens more often than expected

For sure the list is no complete but before going on, please let me know if this is what you expected.

Yes dear Dr. Martin, I meant that, your answer is what I expected, but not limited to power electronics components only, but all power system components.

Great thanks, Please go on .. I would be grateful.

Generally, external factors that results into power systems component outage can basically categorized into two namely

1. Environmental factors; this includes natural phenomena likes lightning, rains (moisture which causes high voltage insulation breakdown of 11, 33, 132  and 330Kv etc insulators). 

2. Human Vandalism and animal interference

The likelihood of occurrences can be approached using probabilistic methods base on proven scientific phenomena, e.g. Monte carlo simulations.

The outage cause by such external factors like environment often results in insulation breakdown effects, hence the need for insulation coordination evaluation/analysis before and after  occurrence. This will give an idea on the severity of the external influence as it relates to power system reliability, security and quality of supply.

I hope this is in the right direction

Regards