Air Circuit breakers

[benji]

3mtr not long could there be enough protection on hv side

 

[Engineer54]

The MV side of the TX protection, is normally sensed from the LV side, via protection relays!! Which is why i asked if there was an DNO LV switchboard in the substation. 3m doesn't seem long enough to connect directly onto the TX LV connection bushings/bars. Could also be the location of the protection CT's, (if any) on those LV bushings. Weird set-up all round if what the OP is saying is correct...lol!!

 

[benji]

only reason i asked about length of lv cables was because we did something similar lv was 12mtr with no protection ,but we were installing a c/o panel and installing new 630mm singles 22mtr run we had to install new acb cubicle near tx

 

[SW1970]

Where do these 3m of tails connect to in the substation, directly to the Transformer or to a LV DNO Switchboard??
I can't believe there is absolutly no protection provided between the TX LV terminals and your unprotected main switch!!! Loops as you call it, are normally only seen at the MV/HV side of transformers, by means of RMU's (Ring Main Units)....

My advice, is to get a Qualified Electrical Engineer involved in your planned project now, tell him your requirements, and let him make the dicissions on how to go about achieving them in a cost effective way... Or, Panel manufacturers can also be given the task of providing your needs. Who will send an Electrical Engineer to assess what you have, and what you need and propose a design to meet them, based on/around their panel systems... You could ask 2 or three such manufacturers to quote on your project.

And ask the Engineer to do a discrimination study on the whole set up by the looks of things...