Insulated Terminal Voltage Ratings

[Tigger]

Hi, We are working on a Solar installation in the UK and have been asked to replace the string cable terminations, 6mm² yellow insulated ring terminals that are bolted to a common busbar. The reason stated is that the insulated terminals are not rated for the string voltages, 1000Vdc STC. Having searched the internet I have found that Cembre insulated terminals have a Maximum Voltage Rating – 0.6kV | 600 Volts | LV Low Voltage.

It is assumed that the LV Low Voltage is the AC voltage and would it be correct to assume that the DC rating would be 1.5x the LV Low Voltage rating i.e. 1.5x600=900Vdc?
See attached image, sorry for the quality of the image.

Any help regarding this would be appreciated.

 

[Lucien Nunes]

Your logic re. the voltage rating is good, and 600V seems to be a common voltage rating, but it would be nice if they were a bit more explicit.. Some good terminals e.g. PIDG are lower, claiming only 300V. I didn't immediately spot any that were higher. I suppose the actual withstand is very much higher still, maybe many kV, but after it has been crimped it might be thin and stressed in the crimping zone so it only merits quite a low rating.

IMO that is an odd argument they are putting forward. The busbars are not insulated at all so it seems a bit daft to insist that the terminal insulation - which only affects the yellow bit - is rated to a specific voltage as there doesn't seem to be any way for them to touch anything.

Personally, I would prefer to see the wiring dressed clear of the busbars, some of it looks tight e.g. the leads from the top busbar going to the lower rail seem to be chafing against the top edge of the lower busbar. And the lead to the 3rd MCB in the top row is simply too short so the terminal isn't properly clamped in place. And to me that kind-of defeats the importance of the insulation voltage of the yellow sleeve of the crimps.

 

[James]

Moving on from @Lucien Nunes post, I suppose the obvious thing to do is replace the yellow insulated ring crimps with uninsulated crimp lugs.

 

[snowhead]

As James above, or strip the Yellow off the crimps if it's suspected it's going to catch fire (would have put a funny Imoji here)
And are the Blue Ferrules 1000v and also the cable between??

 

[Tigger]

Cheers Guys, we have decided to use uninsulated lugs (as James suggested) with adhesive lined heat shrink, we believe the whole issue with voltage ratings in this situation is nonsense as all the terminations on the respective busbars are at the same potential and polarity and the busbars are sufficiently spaced. Snowhead, you are correct to have spotted the bootlace ferrules and ask the question about their rating. In addition to the above we have proposed installing Plexi screens/with Danger labels to avoid exposed conductors being touched while energised.

Once again cheers for sharing your thoughts.