HS code-based commodity chain analysis

List of contents of this article:

• 1,HS code-based commodity chain analysis What is TH system, TT system, IT system? Why is it recommended to use three-phase five-wire system?
• 2, What are tn system and IT system?
• 3, What is TT, IT, TN, (TN-C, TN-S, TN-C-S) system?
• 4, How to choose the transformer wiring method, what are the applicable conditions of different wiring methods, please ask the expert to answer...

What is TH system, TT system, IT system?Why is it recommended to use three-phase five-wire system?

TT TN IT power supply system is named according to the different neutral point grounding N, public protection line PE, and protection neutral line PEN junction. The TT system refers to the three-phase four-wire, the neutral point is directly grounded, and the equipment is connected to the PE line. That is, the equipment shell is directly grounded.

TT system is a system in which the neutral point of the power supply is directly grounded and the shell of the electrical equipment is also directly grounded. Usually, the grounding of the neutral point of the power supply is called working grounding, and the grounding of the equipment shell is called protective grounding. In the TT system, these two groundings must be independent of each other.

TT system is a system in which the neutral point of the power supply is directly grounded, and the exposed conductive part of electrical equipment is also directly grounded. Usually, the grounding of the neutral point of the power supply is called working grounding, and the grounding of the exposed conductive part of the equipment is called protective grounding.In the TT system, these two groundings must be independent of each other.

TT system: neutral point grounding of the power transformer, and the protective grounding of the electrical equipment shell. IT system: The neutral point of the power transformer is not grounded (or through high-impedance grounding), and the electrical equipment shell electrical equipment shell is grounded protectively.

Ine.e. in the past, it was called the protective grounding of the three-phase three-wire power supply system. The neutral point of the power supply of the TT system is directly grounded; the metal shell of electrical equipment is also directly grounded, and has nothing to do with the grounding of the neutral point of the power supply. That is, the protective grounding in the three-phase four-wire power supply system in the past.

What are tn system and IT system?

1. The it system is a system in which the neutral point of the power supply is not grounded and the exposed conductive part of the electrical equipment is directly grounded; the tt system is a system in which the neutral point of the power supply and the exposed conductive part of the electrical equipment are directly grounded; the tn system is the neutral point of the power supply is directly grounded and the conductive part of the electrical equipment is exposed. A system that is directly electrically connected to the neutral point of the power supply.

2. The second capital letter T indicates that the shell of electrical equipment is directly grounded, but it is not connected to the grounding system of the power grid;N indicates that the shell of the electrical equipment is connected to the grounding neutral wire of the system. TN system: the neutral point of the power transformer is grounded, and the exposed part of the equipment is connected to the neutral wire. TT system: neutral point grounding of the power transformer, and the protective grounding of the electrical equipment shell.

3. The IT system is the international standard IEC60364 that distinguishes three different types of grounding systems, and uses two letter codes to represent TN, TT and IT. The first letter indicates the relationship between the power supply end and the ground: T indicates that the power supply end is a little directly grounded; I means that all the charged parts of the power supply end are not grounded or a little grounded by impedance.

4. The TN system is a system in which the neutral point of the power supply is directly grounded, and the exposed conductive part of the equipment is directly electrically connected to the neutral point of the power supply. In the TN system, all electricalThe exposed conductive parts of the equipment are connected to the protection line and connected to the connection point of the power supply, which is usually the neutral point of the power distribution system.

5. [Answer]: TN, TT and IT systems are the three grounding types in the low-voltage power distribution system respectively. In the TN system, the neutral point of the power supply is directly grounded, and the shell of the electrical equipment is connected to the connection point with a protection line. TN can be divided into three systems.

What is TT, IT, TN, (TN-C, TN-S, TN-C-S) system?

1. [Answer]: TN, TT and IT systems are the three grounding types in the low-voltage power distribution system respectively.In the TN system, the neutral point of the power supply is directly grounded, and the shell of the electrical equipment is connected to the connection point with a protection line. TN can be divided into three systems.

2. The TT system is a system in which the neutral point of the power supply is directly grounded and the shell of the electrical equipment is also directly grounded. Usually, the grounding of the neutral point of the power supply is called working grounding, and the grounding of the equipment shell is called protective grounding. In the TT system, these two groundings must be independent of each other.

3. Then this system is called the TN-C system; if the N line in the system is all separated from the PE line, then this system is called the TN-S system; if the previous part of the system, the N line and PE are combined into the PEN line, and the latter part of the line, the N line and the PE line are completely or partially separated. Then this system is called TN-C-S system.

4. The neutral point of the power supply of the TN system is directly grounded, and there is a neutral line leading out.According to its protective line form, the TN system is divided into three types: TN-C system, TN-S system and TN-C-S system.

5. TN system is divided into TN-C, TN-S and TN-C-S system. TN-C system: the protection line and the neutral line are combined into the PEN line. TN-S system: the protective line is separated from the neutral line. TN-C-S system: The protection line and neutral line near the power supply side are merged into a PEN line, and it is divided into a protection line and a neutral line from a certain point.

How to choose the transformer wiring method, and what are the applicable conditions for different wiring methods? Please ask experts to answer...

1, V/220V low-voltage power distribution system can be divided into: IT system, TT system and TN system according to the form of protective grounding. The power supply neutral point of the IT system is ground-insulated or grounded by high impedance, while the metal shell of electrical equipment is directly grounded. Namely: In the past, it was called the protective grounding of the three-phase three-wire power supply system.

2. This is the same connection method. The commonly used are Y-Y, D-Y. The Y-type is usually called the star connection method, and the D-type connection method is usually called the triangular connection method. The line voltage of the star connection method is 3 times the root number of the phase voltage, and the line current and the phase current are equal. The line voltage of the triangular connection method is equal to the phase voltage.

3. Single busbar wiring All power inlet and lead-out wires are connected to the same set of busbars. Single busbar wiring is suitable for small substrates with fewer output circuits. It generally provides tertiary load, and the single busbar of two-way power supply inlet can provide secondary load.Segmented single busbar wiring 1 When the two power supplies are used and the other is spared, the segmented circuit breaker is turned on and operated.