Motors & Equipment第 97 / 120 题
A hermetic refrigerant motor-compressor has a rated-load current of 20 amperes. What is the maximum branch-circuit short-circuit and ground-fault protective device at the standard 175 percent figure?
a.60 amperes
b.25 amperes
c.45 amperes
d.35 amperes
解析
Protection for a motor-compressor is sized at not more than 175 percent of the rated-load current: 20 x 1.75 = 35 A, which is a standard rating. Where that device still will not carry the starting current it may be increased, but never above 225 percent, which here would be 45 amperes. A 25-ampere device is below the calculated value and would nuisance trip on start.
法律依据: 2023 NEC §440.22(A)免费刷完整 120 道题库 — 无需注册。
同考点相关题目
- A continuous-duty motor over 1 horsepower has no marked service factor and no marked temperature rise. What is the maximum overload device rating as a percentage of nameplate full-load current?
- Where must a motor disconnecting means be located relative to the motor?
- An air conditioning condensing unit nameplate reads minimum circuit ampacity 24.6 and maximum overcurrent protective device 40. What overcurrent device must be installed?
- For that same 20-ampere rated-load compressor supplied alone, what minimum conductor ampacity is required?
- A surface-mounted luminaire with a completely enclosed light source is installed in a clothes closet. What is the minimum clearance to the nearest point of the defined storage space?
- A recessed luminaire that is NOT identified for insulation contact must maintain what minimum clearance from thermal insulation?