答案:定子绕组的8E%
答案:定子绕组的8E%
A. 与单相重合闸配合使用时,相差高频保护与高频闭锁保护均要求单跳停信
B. 长线路综合重合闸的整定时间应考虑潜供电流的影响
C. 在双电源线路上,通常在检定无压的一侧也同时投入同期检定继电器,两者的触点并联工作
D. 重合闸的基本启动方式是断路器控制开关位置与断路器位置不对应启动方式
解析: (The third question): This question is about auto-reclosure in power systems. The correct statements are B, C, and D. Let's go through them: B. Considering the impact of backfeed current is essential when setting the auto-reclosure time for long lines. This statement is correct as backfeed current can affect the coordination of auto-reclosure. C. On double-end fed lines, it's common to apply simultaneous in-phase checking on both sides, with their contacts connected in parallel. This statement is correct as this practice ensures proper coordination and avoids unwanted reclosures. D. The fundamental start-up method for auto-reclosure is when the circuit breaker control switch position does not match the circuit breaker position. This statement is correct as it describes one of the typical start-up methods for auto-reclosure. In summary, the correct answers for the three questions are: ABD A BCD
解析:发电机励磁回路发生接地故障时,将会使发电机转子磁通产生较大的偏移,从而烧毁发电机转子。 A.正确 B.错误 答案:B 题目解析:这道题考察的是发电机励磁回路发生接地故障时的影响。实际情况是,当发电机励磁回路发生接地故障时,可能会引起一些异常情况,但通常不会导致发电机转子磁通产生较大的偏移并烧毁转子。因此,这道题的答案是错误(B)。
A. 立即动作
B. 延时动作
C. 不应动作
解析:题目解析 当变压器外部故障时,有较大的穿越性短路电流流过变压器,这时变压器的差动保护不应动作。答案选择C。差动保护的主要目的是保护变压器内部绕组免受故障影响,当发生外部故障时,穿越性短路电流并不会对变压器内部产生影响,因此差动保护不应动作。
A. 3
B. √3
C. 1.5
解析:用单相电压整定负序电压继电器的动作电压,即对负序电压继电器的任一对输入电压端子间,模拟两相短路。如在A和BC间施加单相电压记下此时继电器的动作电压为Uop,继电器整定电压为负序线电压Uop2则:Uop2=Uop/() A.3 B. √3 C.1.5 答案:B 解析:根据题目描述,动作电压Uop为对负序电压继电器的任一对输入电压端子间,模拟两相短路时的电压。而整定电压Uop2为负序线电压。负序线电压与相电压之间的关系为Uop2 = Uop / √3,所以答案选项B是正确的。