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在检修电话机振铃电路时,可用接地电阻测量仪(简称地阻仪)为话机提供振铃电源。其电路连接如附图所示。 ZC—8型地阻仪为手摇发电机式接地电阻测量仪。当手摇转速为120转/分时,笔者用MF50型万用表交流250V档测得地阻仪的空载输出电压(即AB两点间的开路电压)约为75V,其频率为110～115Hz;当手摇转速降为每分钟60转时,地阻仪的空载输出电压约为40V,其频率约为50Hz左
When overhauling the telephone ringing circuit, you can use the grounding resistance measuring instrument (referred to as earth resistance meter) to provide ringing power for the telephone. The circuit connection as shown in the figure. ZC-8-type resistance meter for hand-cranked generator ground resistance meter. When the hand speed is 120 rev / min, the author uses the MF50 multimeter to exchange 250V gear to measure the ground resistance meter’s no-load output voltage (that is, the open circuit voltage between two points AB) is about 75V and the frequency is 110 ~ 115Hz. When the hand speed is reduced to 60 revolutions per minute, the no-load output voltage of the earth resistance meter is about 40V, and its frequency is about 50Hz