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Earth Switch


Earthing switches are used for earthing and short-circuiting disconnected sections of substation or plant. They are designed for no-load switching and are able to disconnect low charging currents. The charging current is due to overlap of conductor during transmission. The term over lap means that during transmission some times it is necessary to cross one line over the other. For example suppose one transmission is from A to B and other from C to D. During transmission AB will overlapped CD line. Suppose we have to perform maintenance operation on AB line, so we have to close the breaker first than the isolator. Although breaker and isolator are opened voltage (of curse less than the supply voltage, but still dangerous ) will still in this line due to this overlap. The voltage induced due to flux linkage of CD on AB. When it will get a close path current will flow and this is harmful for the work man. So we use earth switch to ground this charging current. Charging current may be due to high voltage also.  














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