O osh1397 Active member Joined Jul 12, 2021 Messages 29 Reaction score 0 Jul 14, 2021 #1 Per NEC Handbook Nse + Nc = 1440, Nc = 1200, SW = 60 kVA. Since it's a step up autotransformer: Sio = 60 kVA * 1200 / 1440 = 50 kVA. However, the answer is Where is my mistake? Last edited: Jul 14, 2021
Per NEC Handbook Nse + Nc = 1440, Nc = 1200, SW = 60 kVA. Since it's a step up autotransformer: Sio = 60 kVA * 1200 / 1440 = 50 kVA. However, the answer is Where is my mistake?
N no_concentrate Active member Joined Mar 26, 2021 Messages 35 Reaction score 15 Jul 14, 2021 #2 Nse + Nc = 1440, Nse = 240 ( 1440-1200) Sw = (1440-1200)*250 =60 kVA. (Sio/Sw) = (Nse + Nc)/Nse Sio = ((Nse + Nc)/Nse )*Sw Sio = 60* (1440 /240) = 360kVA (Nse + Nc)/Nse formula is in handbook at page no 61. Otherwise you can also calculate IL*VL = IH* VH (300A)*1200 = (250*1440) = 360 kVA
Nse + Nc = 1440, Nse = 240 ( 1440-1200) Sw = (1440-1200)*250 =60 kVA. (Sio/Sw) = (Nse + Nc)/Nse Sio = ((Nse + Nc)/Nse )*Sw Sio = 60* (1440 /240) = 360kVA (Nse + Nc)/Nse formula is in handbook at page no 61. Otherwise you can also calculate IL*VL = IH* VH (300A)*1200 = (250*1440) = 360 kVA