根据《低压配电设计规范》,电缆在桥架内敷设时,电缆总截面面积与桥架横断面面积之比,电力电缆不应大于(),控制电缆不应大于()
A. 30%,40%
B. 30%,35%
C. 35%,30%
D. 40%,50%
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Copper is often used as an electrical conductor because it ().
A. has high resistance at low temperatures
B. has a highly polished surface
C. is able to pass current with little opposition
D. holds insulation together well
提高无功电压自动控制水平,推广应用(),提高电压稳定性,减少电压波动幅度。
集中联锁车站的牵出线、机待线、出库线、专用线或其他用途的尽头线入口处的调车信号机前方,应设轨道电路,其长度不得小于()。
A. 10m
B. 15m
C. 20m
D. 25m