某火力发电厂,在海拔1000m以下,发电机变压器组单元接线如图所示。设i1、i2分别

题型:单项选择题 案例分析题

问题:

某火力发电厂,在海拔1000m以下,发电机变压器组单元接线如图所示。设i1、i2分别为d1、d2点短路时流过DL的短路电流,已知远景最大运行方式下,i1的交流分量起始有效值为36kA不衰减,直流分量衰减时间常数为45ms;i2的交流分量起始有效值为3.86kA,衰减时间常数为720ms,直流分量衰减时间常数为260ms。请解答下列各题(计算题按最接近数值选项)。

若220kV断路器额定开断电流50kA,d1或d2点短路时主保护动作时间加断路器开断时间均为60ms。请计算断路器应具备的直流分断能力及当d2点短路时需要开断的短路电流直流分量百分数最接近下列哪组数值()?

A.37.28%、86.28%

B.26.36%、79.3%

C.18.98%、86.28%

D.6.13%、26.36%

考点:电气工程师(发输变电)设备选择设备选择题库
题型:单项选择题 案例分析题
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C.由非金属元素组成的化合物不一定是共价化合物

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C.点火系高压电路故障

D.正常现象

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C.中国银行业协会

D.全国银行间同业拆借市场

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A. search for B. find C. look forD. locate

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A.1/2

B.1

C.2

D.3

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