David,
This looks most like induction to me; a temperature of 85°C may seem high, but it is not unusual for inductive heating to reach temperatures even higher than this. Looking at the visual, there is a coil of some description above the horizontal support, I don’t know what this is, but I assume it is a CT. This could be the source of your ultrasonic signature, and maybe even the induction itself. You indicate this has been observed elsewhere, is it always around these coils? Is this coil located closer to the support than on others?
I suggest you find out what type of metal it is, and the properties of that metal. I have come across very high temperatures on steel components before and after checking I was told that the metallurgical properties would not be affected significantly for that type of steel until it was well over 150°C, so it may be something that you can live with and just monitor. Your biggest concern is that the bar will melt of fail in a way that it touches the busbar, and this is not really hot enough for that to happen. It is in a location that is very unlikely anyone will touch it, so I don’t think you have to worry about anyone burning themselves on it. The busbar also looks very well supported, so even if the support weakens it won’t really affect the structure. So I think you need to absolutely find the source of the ultrasound, and I strongly suspect the coil to be in some way responsible for this. Find out what it is, what it does, and check others for simular signatures (even at a lower level).
www.thermalvision.ie
Bob Berry
BINDT, IRT Level 3 EL, Level 3 CV (ISO 18436)
Thermal Vision
8 Old Fair Green
Dunboyne
Co Meath
Ireland
bob"at"thermalvision"dot"ie
www.thermalvision.ie