08:39 Dec 19, 2011 

In the sense that a poorly fitting lid can represent a thermal resistance to the passage of heat from within the transformer to the outside air, the region upstream of the resistance would indeed be hotter. So the region of high thermal resistance is not the hotspot per se, but can give rise to one close by.

16:10 Dec 18, 2011 

So, would it be fair to say that a region of thermal resistance could be considered a "hot spot" such as Herbie is describing?

13:00 Dec 18, 2011 

Temperature in transformer windings and cooling liquid is all but evenly distributed. Here they obviously try to avoid the formation of such hot spots by an appropriately designed tank lid. If this helps to obtain ubiquitous temperature monitoring ...

12:53 Dec 18, 2011 

Athough I worked on heat transfer problems for quite a few years, I never came across the expression "thermally blind". Thermal bridges, thermal hotspots, thermal resistance, yes. The key thing with transformers is that they must not overheat, so having a thermal resistance where you don't want it is not good, and will lead to local overheating. This is the opposite of a thermal bridge, and probably what is meant here, ie it is a region of high thermal resistance.