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Cable sizing for a 3 phase Chiller

Former Community Member
Former Community Member
I have a question regarding the supply to a 3 phase no neutral Chiller.


The details stamped on the side of the chiller are - 400v / 50hz / 3ph / 386 max amps.


Am I right in thinking as 386amps is the max load shared across the 3 phases then the load per phase is 386\\1.732 (square root of 3) which makes it 223amps per phase so I have sized the SWA feeding this machine at 70mm 3 core with separate 35mm CPC.


Hope to get a unbiased  opinion from other knowledgeable electricians.


Thanks
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    Unless it is a very unusual piece of kit, that current will be per line, so a 400A supply (think of that as  3 fuses, each of 400A)

    How big is it, and does it have electronic (inverter) controls. If it is star-delta start, then actually the suply will need quite a bit more in hand to get it going, at least twice that, maybe rather more.

    That is a substantial load, so you will need to find out about the rating of the substation transformer you intend to connect it to, and the length of the route - as others have alluded, voltage drops will get you once you are more than some tens of metres from the substation, and apparently oversized cable may be needed.

    Mike
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  • 0
    Unless it is a very unusual piece of kit, that current will be per line, so a 400A supply (think of that as  3 fuses, each of 400A)

    How big is it, and does it have electronic (inverter) controls. If it is star-delta start, then actually the suply will need quite a bit more in hand to get it going, at least twice that, maybe rather more.

    That is a substantial load, so you will need to find out about the rating of the substation transformer you intend to connect it to, and the length of the route - as others have alluded, voltage drops will get you once you are more than some tens of metres from the substation, and apparently oversized cable may be needed.

    Mike
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