Grounding conductors connected to each other as well as grounding welding, and electrical installation with - weld or bolts. Bolting shall be to ensure a reliable contact, resistance between the bolt and body electrical systems shall not exceed 0.1 ohms, each object is connected to the grounding line grounding individual coupler, serial connection is not allowed, since breakage of one of the conductors turns off from the rest of the grounding device receivers.
The quality of the protective earth judged by its resistance.
In such networks, ground-fault currents are generally not exceed 500 A. For some devices, communications equipment and protective earth resistance can be increased to 10 ohms or more. To determine the technical condition of the grounding device is carried out periodically to check. It includes a visual inspection of the visible, the control connection is secured grounding conductors, the selective opening of ground loop resistance measurement "phase-zero" measured resistance grounding device.
Vanishing is an electrical connection with willful protective earth conductor metal no current-carrying parts that may be under stress. The purpose of vanishing - to turn on the body in the breakdown of one phase short circuit, trigger the protection and disconnect from electrical supply network in the shortest possible time.
As a means of protection are applied fuses or circuit breakers. When a high current (short circuit) fuses burn out or opens the electromagnetic splitters in vending machines, the chain is dropped off and electrical installation of the network.
In addition, unless the network for the closure of the housing scheme vanishing acts as a protective ground, as the body is grounded through the neutral conductor and the neutral grounding resistance. The voltage on the body with respect to ground is reduced.
When the device is a prerequisite for the vanishing of the neutral grounding source. This is done in order to lower the voltage on the neutral wire, therefore, to housing electrical circuit with a random phase to the ground. If you accidentally shorted to ground and no neutral ground and neutral body are under the phase voltage and touching it is life threatening.
Protective earth conductor must necessarily grounded again after a certain distance to overhead lines, for example, every 250 m. |