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改变交流电路的功率因数是师专物理专业学生必做的一个实验.几年来我们都用日光灯电路做此实验.过去在实验当中烧坏灯管现象很严重,主要是因为有的学生在连接测量仪表时,误将镇流器短路所致.为解决这个问题除了实验时多提醒,多照顾外,还可如图所示在线路上接入“时间继电器”.这样,当接通电源时,继电器的一对延时断开的常闭触头先将灯丝短接,如有短路情况,短路电流
Changing the power factor of AC circuit is an experiment that physics majors in teachers college must do.In recent years, we all use fluorescent circuit to do this experiment.It is very serious in the past that the lamp was burnt out in the experiment, mainly because some students in connection measurement Instrument, mistakenly due to short circuit caused by the ballast.In addition to experiment to solve this problem more than remind, take care, but also as shown in the line access “time relay.” Thus, when the power is turned on, the relay Of the normally closed contact with a delay off the first short filament, if the short circuit, short circuit current