Electrical Schematic

[Marxman99]

Hi, I am doing course on electrical engineering. I have an electrical schematic. The scheme uses 1000kva transformer, 500kva back-up gen, 2nr 160kva ups (parallel operation).

I have 3 questions:
1. The schematic shows a main 800A fuse and a separate neutral 400A fuse, why cant the fuse 800A switch all phases and neutral together e.g 4pole?

2. The fuses I refer to in 1 above are in the switchpanel, should there be a fuse at the beginning of the incoming cable (cable from the transformer) to protect the cable?

3. In books 3 switches are shown for the wrap-around bypass, why can’t 2 switches be used.

I would very much appreciate answers in layman terms as I have only just started the course.

 

[Twitchboy]

Please continue, this is an interesting thread. Way over my head, but interesting nonetheless.

 

[Jeffmo65]

I think i have successfully uploaded the schematic.

Tony what is a O/L. And why does the Earth fault relay have to be restricted?

hi mate i think the 3 switches will be mains or geny input , ups in and ups out , the bypass allows the ups to be taken out of the equation for maintenance purposes . as regards the neutral switch this is a grey area as normally the neutral can be switched on a 4 pole breaker unless on a pme system . However with the introduction of G59 i do believe this has to be switched seperately .