jhammer619
Member
I thought I understood 3-phase power perfectly well until I had to size a panel with 240 3-phase High Leg Delta service. Going through old forum posts is getting me more confused.
To get the current on each bus bar (line current), a panel schedule I have adds up all the VA on each phase and divides them by 120V for bus bars A and C, and divides by 208V for the "high leg" bus bar B.
Does this sound correct to you all?
(Please forgive me- I'm used to working with 208Y/120V 3 phase)
The way I envisioned doing this was different: I thought to use separate calculations for 3-phase balanced loads, 2-pole single phase loads, and 1-pole single phase loads.
Say my 3-phase loads add up to 10,000VA. Recalling that Total_VA = Vline_line*I_line*1.732, I calculated 10,000/(240V*1.732)=24A in each bus bar
Right off the bat this differs from the panel schedule macro, which gives me 27.8A on legs A and C, and 16A on the high leg B.
I'll leave it at that for now. Thanks in advance for any help!
To get the current on each bus bar (line current), a panel schedule I have adds up all the VA on each phase and divides them by 120V for bus bars A and C, and divides by 208V for the "high leg" bus bar B.
Does this sound correct to you all?
(Please forgive me- I'm used to working with 208Y/120V 3 phase)
The way I envisioned doing this was different: I thought to use separate calculations for 3-phase balanced loads, 2-pole single phase loads, and 1-pole single phase loads.
Say my 3-phase loads add up to 10,000VA. Recalling that Total_VA = Vline_line*I_line*1.732, I calculated 10,000/(240V*1.732)=24A in each bus bar
Right off the bat this differs from the panel schedule macro, which gives me 27.8A on legs A and C, and 16A on the high leg B.
I'll leave it at that for now. Thanks in advance for any help!
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