Thiết bị & Hệ thốngCâu 247 / 521
A 5 HP, 230 V, three-phase motor has an FLC of 15.2 A. What is the maximum nontime-delay fuse permitted by Table 430.52 for branch-circuit protection?
a.26.6 A
b.38 A
c.45.6 A
d.121.6 A
Giải thích
A nontime-delay fuse may be sized up to 300% of FLC: 15.2 x 3.00 = 45.6 A. 26.6 A is 175% (dual-element fuse), 38 A is 250% (inverse-time breaker), and 121.6 A is 800% (instantaneous-trip breaker).
Trích dẫn luật: 2023 NEC §430.52Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A motor's nameplate shows a full-load current of 40 A and a service factor of 1.15. Under NEC 430.32(A)(1), what is the maximum overload device rating at 125% of nameplate FLA?
- For a 20 HP, 460 V, three-phase motor (FLC 27 A), what is the maximum inverse-time circuit breaker rating for branch-circuit short-circuit and ground-fault protection, using the 250% value of Table 430.52?
- Using the same 20 HP, 460 V motor (FLC 27 A), what is the maximum dual-element (time-delay) fuse permitted by Table 430.52 for branch-circuit short-circuit and ground-fault protection?
- For the same 5 HP, 230 V motor (FLC 15.2 A), what is the maximum instantaneous-trip circuit breaker setting permitted by Table 430.52?
- When sizing branch-circuit conductors and short-circuit/ground-fault protection for a standard motor, which current value does the NEC require you to use?
- Which motor current rating is used to select the running overload (overcurrent) protection device?
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