CN103839657B - A kind of neutral point for transformer and the two grounding system of shell - Google Patents

Abstract

The invention relates to a double grounding system for a neutral point and an outer shell of a transformer. Compared with the prior art, the grounding point of the transformer is easily corroded or disconnected, thereby causing major safety hazards. The invention includes a transformer, a grounding flat iron and a current transformer, the grounding flat iron is fixed and vertically installed on the grounding device, the neutral point of the transformer is connected with the current transformer, and the current transformer and the copper wire nose B of the grounding flat iron pass through The neutral point grounding wire is connected, and the grounding point of the transformer casing is connected to the copper wire nose A of the ground flat iron through the transformer casing grounding wire. The distance between copper wire nose A and copper wire nose B is 60mm, and the copper wire nose A and copper wire nose B are connected by wiring, and the specification of wiring is BVR35. The invention ensures that the effective grounding can continue to be maintained after a grounding terminal is corroded and disconnected.

Description

A Neutral Point and Shell Double Grounding System for Transformer

technical field

The invention relates to the technical field of transformers, in particular to a double grounding system for a neutral point and a shell of a transformer.

Background technique

my country's rural areas are vast, and the location of rural power grid lines is relatively complicated. In order to prevent lightning damage to distribution transformers during thunderstorm seasons and ensure the safe and stable operation of distribution transformers, power supply companies will implement lightning protection measures for transformers. At present, the lightning protection grounding of rural distribution transformers is generally divided into OP grounding mode and NP grounding mode. But from the point of view of practical application, there are certain deficiencies in these two grounding methods. Especially in areas with high levels of thunder and pollution, the grounding point is prone to corrosion or disconnection due to external effects, so that the neutral ground of the transformer is not grounded, which brings major safety hazards. How to develop a grounding system for transformers with high safety factor and high reliability has become an urgent technical problem to be solved.

Contents of the invention

The purpose of the present invention is to solve the defects in the prior art that the grounding point of the transformer is prone to corrosion or disconnection, thereby causing major safety hazards, and provides a double grounding system for the neutral point and the shell of the transformer to solve the above problems.

In order to achieve the above object, the technical scheme of the present invention is as follows:

A neutral point and shell double grounding system for a transformer, including a transformer, a grounding flat iron and a current transformer, the grounding flat iron is fixed and vertically installed on the grounding device, the neutral point of the transformer is connected to the current transformer, The current transformer is connected to the copper wire nose B of the grounded flat iron through the neutral point grounding wire, the ground point of the transformer shell is connected to the copper wire nose A of the grounded flat iron through the transformer shell grounding wire, and the copper wire nose A is connected to the copper wire The distance between nose B is 60mm, and the copper wire nose A and copper wire nose B are connected by wiring, and the specification of the wiring is BVR35.

The specifications of the neutral point grounding wire and the transformer casing grounding wire are both BVR35.

The copper wire lug A is located at the upper end 50mm of the ground flat iron.

A lightning arrester is also included, and the lightning arrester is connected with the ground flat iron.

Beneficial effect

Compared with the prior art, the double grounding system for the neutral point and the casing of the present invention can prevent potential safety hazards caused by non-grounding of the neutral point of the transformer after one grounding point is corroded or disconnected by external effects , to ensure that the effective grounding can continue to be maintained after a corrosion disconnection occurs at a grounding terminal. The grounding wire of the arrester and the neutral point of the low-voltage winding are grounded separately, which can prevent the lightning current flowing through the arrester, and the voltage drop on the grounding resistance is applied to the winding of the transformer; The residual voltage of the lightning arrester and the voltage drop of the lightning current on the grounding resistance will not act on the insulation in the equipment.

Description of drawings

Fig. 1 is the circuit schematic diagram of the present invention

Fig. 2 is a structural representation of the present invention

Fig. 3 is the installation structure drawing of ground flat iron of the present invention

Among them, 1-drop-out fuse, 2-transformer, 3-current transformer, 4-surge arrester, 5-10KV incoming line, 6-grounding device, 7-JP cabinet, 8-grounding flat iron, 9-transformer shell grounding Line, 10-neutral point grounding wire, 11-cloth wire, 12-380V incoming line, 13-reactive power compensation device, 14-metering device, 15-control switch, 16-outlet terminal, 81-copper wire nose A, 82 - Copper wire lug B.

detailed description

In order to have a further understanding and understanding of the structural features of the present invention and the achieved effects, the preferred embodiments and accompanying drawings are used for a detailed description, as follows:

As shown in FIG. 1 and FIG. 2 , a neutral point and shell double grounding system for a transformer according to the present invention includes a transformer 2 , a grounding flat iron 8 and a current transformer 3 . The grounding flat iron 8 is fixed and vertically installed on the grounding device 6, and the grounding function can be achieved by the grounding flat iron 8. The neutral point of the transformer 2 is connected with the current transformer 3, as shown in Figure 3, the current transformer 3 is connected with the copper wire nose B82 of the ground flat iron 8 through the neutral point grounding wire 10, and the neutral point of the transformer 2 is drawn to After the current transformer 3, lead to the ground flat iron 8 from the current transformer 3. As shown in Figure 2, in actual use, the current transformer 3 is installed in the JP cabinet 7, so it can also be drawn from the JP cabinet 7 to the grounded flat iron 8, reaching the neutral point of the transformer 2 and grounded through the current transformer 3 Effect. The shell grounding point of the transformer 2 is connected to the copper wire nose A81 of the grounding flat iron 8 through the transformer shell grounding wire 9 , so that the shell of the transformer 2 is also grounded on the grounding flat iron 8 . Both the copper wire lug A81 and the copper wire lug B82 are located on the ground flat iron 8. In order to ensure the grounding effect, the distance between the copper wire lug A81 and the copper wire lug B82 is 60mm. The copper wire lug A81 and the copper wire lug B82 are connected through the wiring 11, and the specification of the wiring 11 is BVR35. In this way, the neutral point of the transformer has two grounding lines, the current transformer and the transformer shell, which ensures that the effective grounding can continue to be maintained after one grounding terminal is corroded and disconnected at one grounding terminal.

As shown in Figure 1, the 10KV incoming line 5 is connected to the 380V incoming line 12 through the drop-out fuse 1, transformer 2, and current transformer 3, and the lightning arrester 4 is connected between the drop-out fuse 1 and the transformer 2, and the 380V incoming line 12 is respectively connected with a reactive power compensation device 13 and a plurality of outlet terminals 16, and metering devices 14 and control switches 15 are installed on the outlet terminals 16. The double grounding system of the neutral point of the transformer 2 and the casing can suppress the overvoltage of the low-voltage grid outgoing line when the high-voltage line and the low-voltage line are lapped and the insulation breakdown between the high-voltage and low-voltage windings of the distribution transformer, and there is a certain leakage of the lightning strike overvoltage of the low-voltage grid ability. When the single-phase is grounded, the grounding current is large, which can make the leakage protection device operate reliably, remove the fault in time, and play a good safety effect.

In order to ensure the use effect, the specifications of the neutral point grounding wire 10 and the transformer casing grounding wire 9 can be BVR35, and the copper wire lug A81 is located at the upper end 50mm of the grounding flat iron 8 . A lightning arrester 4 may also be included, and the lightning arrester 4 is connected to the ground flat iron 8 . Since the copper wire lug A81 is connected to the copper wire lug B82 through the wiring 11, which is equivalent to a parallel connection, the total grounding resistance is greatly reduced, and thus the voltage drop when struck by lightning is also greatly reduced. To prevent the lightning current flowing through the arrester, the voltage drop on the grounding resistance is applied to the winding of the transformer. The lightning arrester is connected to the transformer shell and grounded together, the ground voltage on the winding, that is, the voltage of the main insulation is limited to the residual voltage of the lightning arrester, and the voltage drop on the grounding resistance will increase the potential of the shell, causing reverse flicker to the low-voltage winding; To avoid the occurrence of reverse flicker, the neutral point of the transformer low-voltage winding is also connected to the transformer shell, so that the neutral point and the shell are always kept at the same potential.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and the description are only the principles of the present invention. Variations and improvements, which fall within the scope of the claimed invention. The scope of protection required by the present invention is defined by the appended claims and their equivalents.

Claims (4)

1. A neutral point and shell double grounding system for a transformer, including a transformer (2), a grounding flat iron (8) and a current transformer (3), the grounding flat iron (8) is fixed and vertically installed on the grounding device ( 6), characterized in that: the neutral point of the transformer (2) is connected to the current transformer (3), and the current transformer (3) and the copper wire nose B (82) of the grounded flat iron (8) pass through the middle The neutral point ground wire (10) is connected, the shell ground point of the transformer (2) is connected to the copper wire nose A (81) of the ground flat iron (8) through the transformer shell ground wire (9), and the copper wire nose A (81 ) and the copper wire lug B (82) are 60mm apart, and the copper wire lug A (81) and the copper wire lug B (82) are connected through the wiring (11), and the specification of the wiring (11) is BVR35. 2. A neutral point and shell double grounding system for transformers according to claim 1, characterized in that: the specifications of the neutral point grounding wire (10) and the transformer shell grounding wire (9) are the same for BVR35. 3. A double grounding system for a transformer's neutral point and shell according to claim 1, characterized in that: said copper wire lug A (81) is located at 50 mm from the upper end of the grounding flat iron (8). 4. A double grounding system for the neutral point and the shell of a transformer according to claim 1, characterized in that it also includes a lightning arrester (4), and the lightning arrester (4) is connected to the grounding flat iron (8) .