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What is the use of the tn-c-s system? In view of this problem, this article introduces the corresponding analysis and answers in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way.

TN-C-S mode power supply system in the temporary power supply of building construction, if the front part is TN-C mode power supply, and the construction code stipulates that the construction site must use TN-S mode power supply system, then the PE line can be separated from the general distribution box at the back of the system. The characteristics of TN-C-S system are as follows.

1) the working zero line N is connected with the special protection line PE. When the unbalanced current of the line is relatively large, the zero protection of electrical equipment is affected by the zero line potential. There is no current on the PE line from point D to the back, that is, there is no voltage drop on the wire, so the TN-C-S system can reduce the voltage from the motor housing to the ground, but it can not completely eliminate this voltage, which depends on the load imbalance of the ND line and the length of the ND line. The more unbalanced the load is and the longer the ND line is, the greater the voltage offset from the device shell to the ground is. Therefore, it is required that the load imbalance current should not be too large, and repeated grounding should be made on the PE line.

2) the PE line cannot enter the leakage protector under any circumstances, because the action of the leakage protector at the end of the line will cause the previous leakage protector to trip and cause a large-scale power outage.

3) for the PE line, except that the N line must be connected with the N line at the main box, the N line and the PE line shall not be connected, the switches and fuses shall not be installed on the PE line, and the earth shall not be used as the PE line.

Through the above analysis, the TN-C-S power supply system is a temporary modification on the TN-C system. When the grounding condition of three-phase power transformer is good and the three-phase load is relatively balanced, the effect of TN-C-S system in construction power consumption practice is feasible. However, when the three-phase load is unbalanced and there is a special power transformer at the construction site, the TN-S power supply system must be adopted.

Extended data

1. In the power supply mode symbol stipulated by the International Electrotechnical Commission (IEC), the first letter indicates the relationship between the power (power) system and the ground. For example, T means that the neutral point is directly grounded; I means that the power supply is isolated from the earth or the point of the power supply is connected to the earth by a high impedance (for example, 1000 Ω;) (I is the first letter of the word "isolation" in French Isolation).

2. The second letter indicates the relationship between the exposed conductive part of the electrical device and the ground. If T indicates that the equipment shell is grounded, it is not directly related to any other ground point in the system; N indicates that the load is protected by zero connection.

3. The third letter indicates the combination of the working zero line and the protective line. For example, C means that the work zero line and the protection line are one, such as TN-C; S means that the work zero line and the protection line are strictly separated, so the PE line is called a special protection line, such as TN-S.

The answer to the question about the usefulness of the tn-c-s system is shared here. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel to learn more about it.

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