Cable cross-sectional area calculation
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A 220VAC UPS is used to supply power to downstream devices, which have a capacity of 2KVA each. The distance between these devices is 480 meters. What should be the cross-sectional area of the 3-core ZR-YJV cable used? What is the basis for the design?
Based on the current-carrying capacity, the voltage drop caused by the cable length is taken into account (in other words, as the cable length increases, its resistance rises, resulting in a voltage drop). 2KVA / 220V = 9 A. According to the rule for cable current capacity, for cross-sections of 10 mm2 or less, 5 A is considered per mm2. Taking into account a distance of 480 meters, a cable with a cross-sectional area of 4 mm2 should be sufficient. That is, 3*4mm2 ZR-YJV cable (or 3*4mm2+1*2.5mm2 ZR-YJV cable). Please give me some advice.
My god! The cable I designed is ZR-YJV 3x16mm2; the difference is huge. Voltage drop for a 6-square cable: △u% = 2△Ua%IL = 2*1.476*10*480/1000 = 14%; voltage drop for a 10-square cable: 8%; voltage drop for a 16-square cable: 5.5%. The value may be higher depending on the sensitivity settings chosen.
Expert, I’ve learned it; I didn’t pay much attention to the voltage drop calculation.