该种仪表的黑色端子只与其外壳相连,当插入电源插座时,并没有与电网的地相连。只有三端插头是真正接地的。但不管是否真正接了大地,只要在测量中将各种电子仪表的黑色端子连在一起,则其外壳就连在一起了,即都处于某电位点。这个公共点虽然不一定是接地点,我们也需称之为“共地端”。当电磁干扰袭来时,会被各仪表的外壳短路到“共地端”,也同样起到屏蔽的作用。
附图一是在示波器上看到的50Hz工频电压波形。附图二是迭加了50Hz工频干扰有用信号。附图三是迭加了高频干扰的有有用信号。GE FANUC IC600BF831K INPUT MODULE W/ 44A717558-G01 PC B
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10 TELEMECANIQUE ABR-1S618B RELAY MODULES ABR1S618B
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