You need scrambled brains to sort this!

[Chr!s]

Err, ....this ''IS'' all 400 Volt stuff!!! Only untill you get to the other side of the TX's will you be in MV territory!! ...lol!!!

But there are lots of differing protection schemes for various systems, you need to be able to calculate the fault levels through out the system, so you need to understand the Mv side of things to set up your Protection scheme. Their is a lot of Math involved, its degree level not 2330 lol.

 

[Engineer54]

But there are lots of differing protection schemes for various systems, you need to be able to calculate the fault levels through out the system, so you need to understand the Mv side of things to set up your Protection scheme. Their is a lot of Math involved, its degree level not 2330 lol.

Very true, there are protection relays on the LV switchboard that will intentionally trip out the TX feeder on the MV side of things. But the fault levels throughout the system, would have been calculated long before the MV and LV main switchboards were even ordered, You can't change a switchboards fault level rating, not without virtually dismantling the thing anyway. The preliminary ''Protection Co-Ordination Study'' is also calculated prior to the design/layout and manufacture of the Switchboards, The settings finalised after full testing and commissioning has been completed, and final adjustments to settings on protection relays and/or ACB integrated protection settings made. Which will also affect all downstream protection set-ups in sub-main panels and even beyond...

But having said all that, to all intendant purposes, the LV switchboard will still be a 400 volt system. Agreed probably outside the scope and experience of most installation electricians that are not involved in industrial or large commercial projects.... My comment was only meant to basically point out that, we aren't talking about MV, but to a 400 volt LV main distribution system...

 

[Engineer54]

PS the earth bars are on the drawing.

I know what the earth symbol would mean on your drawing and why, for clarity. But to others that are not aware the TX N-E link would be made at the Main Switchboard, it wouldn't be obvious. The main LV earthing/bonding arrangements would be connected to a substantial earth bar (also with a removable link for testing purposes) located on a convenient sub-station wall.

 

[Knobhead]

Fair comment, it's a case of I've always drawn them that way. At the end of the day the drawing wasn't intended for here.

I'm on the look out for something similar, It's got to be readable but not obvious.
It can develop in to fun when guys from all over the world can't even agree a translation. It doesn’t help when you’ve a guy from Sri Lanka describing a protection fault on a turbo-alternator using every acronym you could think of interspersed with TXT (SMS) talk. The replys can get a bit colourful (not in a racist way though).

There’s one I can think of that’s mechanical involving a motor and a ball mill. By the time we’d realised all the gearbox calculations were arse about face we would have built a centrifuge.