There are several ways to ground the neutral point of a transformer

There are many ways to ground the neutral point of a transformer, among which the most commonly used are TN and TT, and there are also some relatively rare ones. Grounding method. This article will introduce the transformer neutral point grounding method in detail from these aspects.

1. TN grounding method

TN grounding method is also called direct grounding method, that is, the neutral point of the transformer is directly connected to the ground, and all user loads are connected to corresponding On the phase line. TN grounding methods are divided into three methods: TN-C, TN-S and TN-CS.

1. TN-C grounding method

The TN-C grounding method refers to merging the neutral wire and the protective wire together when the power supply is supplied. This is one of the three types of cables. kind of. Since the neutral line and the protection line are merged together, it is also called the "combined line". When a fault occurs through an electrical ground, the current in the wire leaves through the protective wire, keeping people safe.

However, when using the TN-C grounding method, you need to pay attention to the ability of the protective wire to withstand the rated current, because once the protective wire fails, the entire wire system will no longer be safe.

2. TN-S grounding method

TN-S grounding method refers to the use of separate protection lines and neutral lines, which are connected to the ground respectively, and are grounded better than TN-C The method is safer and more reliable. Therefore, the TN-S grounding method has become the mainstream grounding method at present. In this grounding method, when user equipment or electrical equipment fails, the generated current leaves the electrical system through special protection wires, which can ensure the safety of the electrical system operation from the perspective of personnel safety.

3. TN-CS grounding method

TN-CS grounding method is a combined grounding method. It is a combination of TN-C and TN-S grounding methods, and is also used as a neutral line by combining the combination line and the protection line. Similarly, the TN-CS grounding method also has some disadvantages, that is, due to the existence of the combination line, when the combination line and the protective wire junction fail, the wire system will no longer be safe. Therefore, when using the TN-CS grounding method, attention should also be paid to the protective line. Ability to withstand rated current.

2. TT grounding method

TT grounding method is a grounding method for the neutral point, which is different from TN grounding method. In this case, the neutral point of the transformer is directly connected to ground, but the wire connected to the cable hole is another ground wire. Each user device needs to be individually labeled. This grounding method has high requirements for the insulation ability of electrical equipment, and users cannot be connected to each other casually, which has certain limitations.

3. Other grounding methods

1. IT grounding method

IT grounding method means that the neutral point of the transformer is directly connected to the ground through a high resistance , thus forming a neutral ground insulation. This wiring method is commonly used in high-precision medical equipment, laboratory equipment, communication equipment, computers and other occasions that require electrical insulation and electromagnetic compatibility.

2. Zig-zag grounding method

Zig-zag grounding method is a special grounding method. It uses a special-shaped transformer with self-winding. This transformer connects two secondary coils to the neutral point of the transformer to ground the neutral point of power and electrical equipment.

Compared with other grounding methods, Zig-zag grounding method is relatively complex, but it can protect transformers and load equipment from external charges and has certain application prospects.

Summary:

In summary, there are many ways to ground the neutral point of a transformer, including TN, TT, IT, Zig-zag and other methods. The TN grounding methods are divided into three types: TN-C, TN-S and TN-CS. In practical applications, we need to select an appropriate grounding method based on comprehensive considerations based on actual conditions and needs.