Allow connecting to power transformers

[ca-d]

So far we can only connect from transformers to other equipment and existing connectivity nodes.

Allowing users to connect power transformers directly to one another presents the problem where to put the connectivity node when they are both not inside bays, which is even worse when there are no bays in the substation.

This is already a problem when grounding power transformers outside bays, since currently the grounding is removed when moving the arbitrary bay containing the connectivity node. This may be quite surprising to the user.

Maybe we should disallow grounding transformers outside bays altogether? What do you think, @danyill ?

[danyill]

I really don't like an unpredictable interface and deleting a bay and finding that "randomly" or "arbitrarily" I have lost any direct grounding on a PTR doesn't seem acceptable.

I would say that no direct grounding should be allowed for transformers placed outside bays and we should put a warning for this in our help/guidance.

In the current prototype if I have no bays I am not able to ground. Would it be possible to make the neutral point terminal colours red to indicate not possible or just not to show them at all (I prefer the red because it is more explicit that something is going or that a possibility is lost).

The only other solution I see is having a "null bay" or a "grounding bay" for this which I really prefer to avoid as it's not terribly semantic.

Perhaps this is one reason why some manufacturers require PTR to be in bays because the standard is not very flexible with ConnectivityNodes in this regard.

[danyill]

Actually that doesn't work. How about a snack bar message saying it can't be done if the user tries direct grounding

[ca-d]

Both suggestions sound better to me than what we have.