6. Analysis of the electrical circuitry
6.4. RCD APPLICATIONS IN THE GROUND TN
So far bo'lshaya of the electrical work in our country with such a grounding system TN-C.
It should be a closer look at the operation of the RCD in such installations.
In such an installation, the breakdown of the insulation on the body appliance, if the housing is not grounded (for example, a refrigerator or a washing machine Isolation), RCD, included in the appliance, the power circuit will not work because there is no current flow circuit leak - no difference (differential) current. At the same time on the appliance, the housing would be a dangerous potential relative to the ground.
In this case, when you touch person-to-housing appliance, and flows through his body to the ground current in excess of rated residual current of the RCD (the current setting) - I D n, RCD reacts and disconnects the electrical installation of the network, resulting in a person's life will be saved.
This means that in the above case, since the occurrence of insulation failure on the housing and the appliance, the electrical potential before the disconnection of faulty network circuit exists between potential hazard.
From the foregoing, it follows that in installations with TN-C earthing system, RCD application is also justified, because the device and in such electrical systems provides effective protection against electrocution.
Electrical systems with earthing systems TN-S, TN-CS, TT in this aspect have a significant advantage: in a similar situation - the breakdown of the insulation on the body, the RCD immediately shut off the power supply, since all bodies have a reliable connection to the protective conductor.
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