Melting cables in my Frigadon chiller 😮

[Dr Frost Bite]

Hi everyone, I've been working on this chiller and during routine maintenance I noticed the cables supplying the overloads that protect the compressors were melting. The bock compressors aren't particularly heavy duty and although I have to admit I can remember the exact run amps I do know it was well within what the 10mm cable can handle, I actually believe that the issue is with the pinch connections used off of the bus bar (it's the exact thing that you use your screwdriver in and lever open while pushing/pulling the cable in or out) but this is scaled up, I don't know if there is a minimum contact surface area for the ampage being pulled, maybe someone has a formula or table? The manufacture wants to increase the cable size but I can see 2 problems with this, first this would not increase the surface contact area by much if any and secondly I don't think the cable size is the issue otherwise I suspect I would see cable damage across the whole cable from the bus bar to the compressor terminals which if course I don't. Anyone had this issue? If so what was the out come. I have 2 compressors isolated out of 5.

[monkey spanners]

Is it a bus bar or din rail connection? Either way if its melting near the connection its the connection is the problem. I'd look into replacing the style of connector one better suited to the application.

[nike123]

I would check with IR camera what is heating, because I have Cat S60! :D

These cables which are melting, are they single copper wire (solid) or multi wire (stranded)? These Wago type connections are usually designed with more amperage capacity on stranded cables!
Check this video:
https://www.youtube.com/watch?v=BZx6wZF6S2o

These are made for 10mm2 cross-section!
Run away from Chinese or less known brands!

Anyway, if your cable is sized for compressor running amperage and not for starting amperage,than you could have these problems because of undersized connection point amperage capacity during compressor start.
If you have , for example, 100A starting current, than connection point should be sized for that amperage!
It is best to oversize these terminals for 1 or 2 size! When I do service on problems like that, I use terminals which have smallest possible size of wire same as my cable! For example, if cable is 10mm2 than I use terminal for 10-25mm2.
If you use screw type terminal, than on stranded wire you must use sleeve!
I would not use spring type connections because of low contact area regarding starting currents in non-inverter compressors.

https://www.youtube.com/watch?v=2uYD8e7idnY

Check this video and see how first is melting insulation at Wago (spring type) conector!

[Dr Frost Bite]

I see what your saying about the start amps, this does happen slowly over time so could be an issue. The cables are multi stranded I assume that this is to take the shape of the connector as it's flexible. Thanks for the video they look similar perhaps even better quality then what is currently installed. I also have a cat60 but it's impossible to get a good view of the connection without risking Electric shock from the melting cables however the cables are hotter at the top where the bus bar it's.