overloaded??

[jim23]

following on from my other post (many thanks to those who took time to give there input by the way) i wonder if anyone had any views on this.....

canalis 400A triple pole+N busbar trunking fed from a busbar chamber. feed is via a swa BS5467 4 core 185mm.

desired supplys connected from the busbar trunking are...

10 x 63A TP switch disconnectors supplying welding sets (using 2 phases only at 25A per phase est)

3 x 10A 3 phase motors.

3 x 100A lathe's ( 3 phase pulling 100A total)

1 x 150A 3 phase sub main db

1 x 30A sub main powering 2 5A light circuits and a 20A radial socket circuit

1 x sub main supplying 3 lighting circuits (10A) each and 2 30A ring circuits.

does this seem overloaded to anyone? ive no idea really about busbar trunking diversity.

 

[SparkyMarky]

Busbar diversity - hmmm, tough one It's a problem I struggle with daily, and there's really no hard and fast rule. One of the main factors to consider is what sort of a shift pattern the factory runs. If it's a bell to bell operation like ours, then 30 seconds after the start of shift / end of tea break you could well have everything being started at once and probably wouldn't want to allow any diversity (plus you'd need to consider the higher start up loads all occurring simultaneously). On the other hand with staggered start up time or intermittent use of the equipment (ie the company only employs three welders so only three welding sets will ever be in simultaneous use) then you could calculate the theoretical maximum demand fairly accurately.

The way I normally handle this type of problem at work is to stick a datalogger on the busbar feed cables and monitor the load over a week to get an accurate profile of the actual loading. Obviously this only works for adding additional load to an existing bar, not for designing a new system...

 

[jim23]

thanks sm, maybe thats something to look into.

my overall feeling is the installation has more things hooked up than it probably should. especially since they are bringing in a new machine also that pulls 100A per phase apparently!

our supply is only 3 x 400A.

any other comments on busbar trunking diversity or assessing demand of an installation would be welcome guys,

cheers.