Thiết bị & Hệ thốngCâu 288 / 521
A feeder supplies three 460 V, three-phase motors: 25 HP (34 A), 15 HP (21 A), and 10 HP (14 A). Per NEC 430.24, what minimum feeder ampacity is required?
a.69 A
b.86.25 A
c.84 A
d.77.5 A
Giải thích
430.24 requires 125% of the largest FLC plus the sum of the rest: (34 x 1.25) + 21 + 14 = 42.5 + 35 = 77.5 A. 69 A omits the 125% factor, 86.25 A applies 125% to all, and 84 A doubles wrongly.
Trích dẫn luật: 2023 NEC §430.24Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
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- What is the rated secondary current of a 75 kVA, three-phase transformer with a 208 V secondary?
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