Calculations第 20 / 110 题
A 75-kVA transformer has a 90-A primary current (over 9 A). With primary-only protection at 125% max, what is the primary overcurrent device rating (next higher standard permitted)?
a.110 A
b.100 A
c.150 A
d.125 A
解析
125% of 90 A = 112.5 A. Where this does not match a standard rating, the next higher standard device (125 A) is permitted for primary-only protection.
法律依据: 2023 NEC 450.3(B)免费刷完整 110 道题库 — 无需注册。
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