The body of the laboratory equipment or the devices that are located in open areas are earthed so that if the phase wire hits the body or if the radiation caused by lightning is supposed to enter the device through the body of the device, this will be prevented. and through earth bypass.
Another role of earth wire is neutralization of induction effects. It may have happened to you that your hand trembled when touching the body of the refrigerator. If you measure the voltage of the body of the refrigerator against zero, it will show 220 volts, but it does not have the ability to turn on the 220-volt lamp, because of the induction of the phase wire on the body. It is a refrigerator, the solution to solve this issue is actually grounding the body of the refrigerator, another way is to reverse the plug of the refrigerator.
In fact, whenever you place a wire with both ends free in parallel and next to a phase wire, the free wire will have the same potential as the phase wire, and you will not be able to detect the real phase wire with a phase meter unless you tell the consumer Connect to find out which one has streaming power.
It should be noted that if our circuits have an independent ground, they generally do not need an earth, and the earth is used for the safety of life and not for establishing the ground in different circuits.
Earth is used where it finds a way to communicate with the phase.
Don’t confuse earth with zero, zero has the ability to flow for infinite bus, but earth is a path with impedance, which is used only for the ESD energy discharge path.
Even if possible, do not connect the ground of the DC parts of your circuit to the ground. Connect the earth only to the device body or cable shield.
In terms of dirty signals, some fields are considered intermediate and connecting some fields in different DC circuits with high frequency circuits is not only useless but also causes interference, for this reason it is necessary to separate LF parts from HF in our design. and also isolate the ground of the analog parts from the digital ground and finally, to protect the whole device, we connect its case to the ground.
In general, compliance with various requirements in the field of EMC, EMI, ESD, shielding, grounding, earthing, and connecting them has a positive effect on the design quality and customer satisfaction, as well as on maintaining the health of the device and the life of the operator, and requires a detailed and practical study. Is .
This post is written by m_vat