Does the ,CT/VT's which is located on busbar before the main circuit breaker, need to have covers on secondary connection points within the scope of 4b forming?

[Anonymous user]

The question is described on title.Since every external circuit or voltage transformer producers do not send plastic covers for     S1-S2 connection points, we need to order them additionaly.

I would like to learn that  can the transformers be mounted on busbar without covers on connection points?

[PascalL · Accepted solution]

The current transformer CT installed on busbars, links between main busbar and devices have no voltage on terminals. That the reason why their terminals are not insulated. To the voltage transformer or power transformer usually they are not installed into the form 4b, because it is not a standard installation the place is lacking. They are installed into an auxiliary area and in any case their terminals are insulated. 

Pascal Leprêtre.

[RHH · Accepted solution]

Hello CFK,

In my experience (for a panel builder), 4b-form is the highest form applicable. This means every component should be insulated and/or change-able when power is still on.

This also means connections with products are separated from the other products or sources.
I have a pdf image which may be useful in getting some insight into this, attached to this reply.

For my opinion; I would insulate as much as possible. You don't want any mass, particles or body parts able to touch anything that has power on it.

If I read the post before me correctly. If the parts were talking about is a component which doesn't have a current or source and you can't touch it and/or cant be touched by other materials falling in. Then its not necessary to do so.

Hope I was of any help.



 

[Anonymous user]

Hello, RHH-Eltechna;

Thank you very much for your kind interest and solution oriented perspective.

As much as I understand from 4b forming, all different functional units must be seperated from each other. 

In this case , you can imagine that there is live busbar (but of course in front of it there is cover to prevent any external touch),

and on that live busbar, we have current transformer.

Firstly, as you know current flows on current transformers secondary points.

Secondly, Busbars and current transformers are completely different functional units for me.

That's why , I think it should be covered.

Many thanks for the file that you shared.

Best Regards,

Cafercan Karsin

[RHH · Accepted solution]

''As much as I understand from 4b forming, all different functional units must be seperated from each other. ''

That is correct.

And in your case I would agree with your perspective and actions.
It would be the most logical thing to do so.


In the main line of thinking, we should look at where the buildings forms are for;

The building forms are made for protecting parts that are guiding or diverting currents to different locations, like a busbar or fuse. Protecting them from any human interaction or falling object.

Thats why this is the form that is most used when customers want to change or pull fuses without having to switch off power to work safely.

I think next to regarding the safety line of things there is also the common sence/practical use of doing so. I think it would be most logical to protect and/or cover such connections as much as possible.

In context; If we build a (standard) form-1 panel, we still cover alot or most of the copper rails from touch/objects even if the build form does not describe its necessity. Just a bit of service/common sense.