Thiết bị & Hệ thốngCâu 286 / 521
For the 75 kVA transformer with a 208 A secondary, what is the maximum secondary overcurrent protective device using the 125% value of Table 450.3(B)?
a.208 A
b.260 A
c.347 A
d.416 A
Giải thích
Table 450.3(B) allows secondary protection at 125% of rated secondary current (currents >=9 A): 208 x 1.25 = 260 A. 208 A omits the factor, 347 A is about 167%, and 416 A is 200%.
Trích dẫn luật: 2023 NEC §450.3Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A rooftop A/C unit has one compressor at 30 A rated-load and a condenser fan at 1.5 A. What is the minimum circuit ampacity (MCA), using 125% of the largest motor plus other loads?
- An HVAC nameplate specifies 'Maximum Fuse or HACR Breaker.' What does HACR indicate?
- What is the rated secondary current of a 75 kVA, three-phase transformer with a 208 V secondary?
- NEC 450.9 requires that transformer ventilation openings be arranged so that they:
- 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?
- Per NEC 430.62, the maximum feeder overcurrent device for several motors equals the largest branch-circuit protective device rating plus the sum of the other motors' FLCs. If the largest motor's branch device is 90 A and the other motors' FLCs total 35 A, what is the maximum feeder device?
Cập nhật gần nhất: · quy trình kiểm tra
Đội Ngũ Biên Tập PrepPass · Đối chiếu với California CSLB C-10 Electrical Trade Examination · Quy trình kiểm tra