Motors & Equipment第 89 / 120 题
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.50 amperes
b.40 amperes
c.46 amperes
d.60 amperes
解析
The disconnecting means must have an ampere rating of at least 115 percent of the full-load current: 40 x 1.15 = 46 A, so a 60-ampere switch would be the practical selection. The 40-ampere answer omits the 115 percent factor entirely, and 50 or 60 amperes are available equipment ratings rather than the calculated minimum the question asks for.
法律依据: 2023 NEC §430.110(A)免费刷完整 120 道题库 — 无需注册。
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