The difference between ground line and zero line

Grounding and then the basic purpose of zero there are two, one required by the work of the circuit grounding; Second, in order to protect the personal and equipment safety grounding or zero. According to their role can be divided into four. A. Working ground; b. Protective earth; c. Protection to zero; d. Repeated grounding.
First, the work of grounding
In the use of 380 / 220V low-voltage power system, usually from the power transformer leads to four lines, that is, three phase and a neutral line, the four do both power and lighting. Power with three phase lines, lighting with a phase line and neutral line. In such a low-voltage system, consider the case of normal or failure, can make the electrical equipment to run reliably, and the safety of people and equipment, the general system of the neutral point directly grounded, that is, work grounding. By the three-winding transformer connected to the neutral line that is also known as the zero line, the point is called the neutral point.
The role of working ground
The role of grounding work, there are two points, one is to reduce the risk of grounding; stabilize the system potential, limit voltage does not exceed a certain range, reducing the risk of high pressure fleeing into low pressure.
Second, protective grounding
Protective grounding is to prevent the electrical installation of the metal shell, power distribution equipment, such as the framework of the tower and the line pole and the safety of people and equipment to carry out the safety ground. The so-called protection of the ground is the normal case of non-charged, and in the insulation material damage or other circumstances may be charged by the electrical part of the metal (that is, with the live part of the insulation phase of the metal structure) with the grounding conductor and reliable connection Protective wiring.
Then the application of protective earthing range:
Protective earthing is applicable to ungrounded grids. In this type of electrical network, any part of the metal, which may present a dangerous voltage due to insulation damage or other reasons, shall, unless otherwise specified, be protected by protective earthing,
(1) metal casing, base of motor, transformer, switchgear, lighting apparatus and other electrical equipment, and transmission connected with it;
(2) metal frame or reinforced concrete frame of indoor and outdoor power distribution devices, and metal block or fence near live parts;
(3) Metal frames or enclosures for power distribution panels, consoles, protective screens and distribution cabinets (boxes);

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