calculation help needed 154 amps

dances

hey everyone need a small bit of help . have recently wired an extension to a factory. that part is fine ive now got two packs brought in from germany by refrigeration crowd they are mounted outside on a steel frame and the control the chillers and condensers in the new area i think. any way one is rated at 60kw and the other is 36 kw both are 3 phase .

i need to calculate the size of cable and breakers i will need and if i have enough power on my sub board to even feed the machines .

i calculated 154amps for both machines 1 gets a 35sq cable and the other gets 25sq . neither run is over 100 meters .

if its rated at 60 kw what is the size of the breaker i will need 80 amp?

also when its 3 phase the 80 amps is divided accross the 3 phases so it realy only pulls 23 amps per phase. is that right.

i realy need help on this one it will cost me a lot of money if i get it wrong

dances

all advice appreciated

Stoner

dances wrote: »

also when its 3 phase the 80 amps is divided accross the 3 phases so it realy only pulls 23 amps per phase. is that right.

First of all IMO always go one size up in SWA and Switch gear (then size down) for refridgeration as it is a contineous load and the heat build up is constant ( we have been cought out here before).

Second of all is the 80AMps a 3 phase current or an equiv single phase as you may need to take root 3 into consideration, so you load per phase could be in the 40 amp + range.

BelaC

The 60kW machine is a quite "big" also if possible at the start U need to using Y arrange of the windings, cos one phase use cca 52Amps (20kW/380V) but the value of starting current is around 5-10 times bigger! -if U use normally Delta arrange-

Stoner, have I right?

dances

hey guys thanks i think i got it. 60 kw is 20 kw per phase so its 90 amps per phase and 45 amps on the 30 kw machine they are 4 fans per machine . so i will use a 35 sq cable and 16 sq and i will feed the sub board which also has lights and sockets etc on it with a 50 sq cable cheers . i hope im right

steifanc

your advise is bad.you should not really be giving advice on matters that could cause great danger to that man ?

steifanc

why would you be useing a delta arangement? unless useing inverters you wouldny be worryied about loads?

Stoner

I guess that as Dances is a sparks that he got his head around it, I understand where BelaC was coming from. Dances took no advice from here, i.e he is a sparks who addressed the issue himself, he also had a lot more information then anyone here had access to documentation etc. that we still dont have, there are still questions about the exact installation.

Dances did not need the more common "DIY" advice that is usually given here, although the forum as I understand it is bigger then "DIY" issues they are still the main reason for this forum.

steifanc I do see where you are coming from and looking into the level of advice given here is very important and thank you for pointing it out.

I'm going to lock this thread now as the OP addressed it himself, one way or another and it could develope into something about something with too many unkowns.

RoundyMooney

+1