Motors & EquipmentCâu 85 / 120
That same motor has a nameplate full-load current of 32 amperes and a marked service factor of 1.15. What is the maximum separate overload device rating?
a.36.8 amperes
b.40 amperes
c.42.5 amperes
d.32 amperes
Giải thích
Overload protection is based on the nameplate current, not the table value, and a service factor of 1.15 or greater permits 125 percent: 32 x 1.25 = 40 A. The 36.8-ampere answer applies the 115 percent factor used for motors with no marked service factor or temperature rise, and 42.5 amperes wrongly applies 125 percent to the table value of 34 A.
Trích dẫn luật: 2023 NEC §430.32(A)(1)Luyện miễn phí toàn bộ 120 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A 25-horsepower, 460-volt, three-phase squirrel-cage motor has a table full-load current of 34 amperes. Using 75 degrees C terminations and copper, what is the minimum branch-circuit conductor size?
- For that 34-ampere three-phase squirrel-cage motor, what is the maximum inverse-time circuit breaker permitted for branch-circuit short-circuit and ground-fault protection, using the next standard size allowance?
- For the same 34-ampere motor, what is the maximum dual-element time-delay fuse permitted at the standard percentage?
- A 5-horsepower, 230-volt single-phase motor has a table full-load current of 28 amperes. What is the minimum copper branch-circuit conductor at 75 degrees C terminations?
- A 30-horsepower, 460-volt three-phase motor has a table full-load current of 40 amperes. What is the minimum ampere rating of the disconnecting means?
- A feeder supplies a 25-horsepower motor (34 amperes) and a 10-horsepower motor (14 amperes), both 460 volts three phase. What minimum conductor ampacity is required?
Cập nhật gần nhất: · quy trình kiểm tra
Đội Ngũ Biên Tập PrepPass · Đối chiếu với Journeyman Electrician Licensing Exam (NEC-based) · Quy trình kiểm tra