Junction box introduction

In home decoration, the junction box is one of the electrical accessories, because the wires used in the decoration pass through the wire tube, and the junction box is used as a transition in the connection part of the wire (such as the line is relatively long, or the wire tube needs to be cornered) Use, the wire tube is connected to the junction box, and the wires in the wire tube are connected in the junction box to protect the wires and connect the wires. This is the junction box

The thermocouple and thermal resistance junction box is a device used to fix the terminal block and as a connector. It plays a role in protecting the temperature sensing element from the external atmosphere and making the external wire and the terminal contact good. According to the measured temperature object and On site environmental conditions and requirements, in addition to ordinary junction boxes, junction boxes such as splash-proof, waterproof and plug-in types are also designed. If we assemble various types of junction boxes into thermocouples and thermal resistance products, these products are correspondingly splash-proof, waterproof and plug-in thermocouples and thermal resistances.

Thermocouples and thermal resistances are different from other types of instruments (such as display instruments, regulators, etc.). They are usually installed on field devices, and the environmental conditions of field devices are generally harsh.

In the past, the junction boxes that were not uniformly designed not only had few varieties, but also had many shortcomings: for example, poor sealing performance, and the screws on the cover and the cover were easy to fall (especially the screws for high-altitude operations were dropped and could not be found). In terms of standardization, wearing parts cannot be interchanged, such as screws, covers, terminal blocks, outlet bolts and sealing rings, etc., which are not uniform and cannot be replaced. All the above have brought great difficulties to the users.

The junction boxes of thermocouples and thermal resistance products that have been uniformly designed, based on the opinions and requirements of the user, have overcome and improved the above-mentioned shortcomings, and designed the following four junction boxes. These four junction boxes, except for The external dimensions that do not affect the interchange are not specified, and the dimensions that affect the interchange of parts are uniformly specified.

classification

Ordinary junction box

The following figure shows the ordinary junction box, which has a simple structure and can ensure that the junction seat and the protective tube are firmly connected to the junction box. The connection between the different wires and the temperature sensing element through the terminal post has good electrical contact performance.

Ordinary junction boxes are usually used in places with good environmental conditions and no corrosive atmosphere.

Plug-in junction box

The following figure shows the plug-in junction box, which is characterized by easy assembly and disassembly, and uses the standard product of the connector manufacturer.

It can prevent dirt from invading into the junction box and ensure good electrical contact performance, so it is suitable for dry and dusty sites. It can be quickly disassembled and assembled during use, thereby reducing the influence of high temperature or dust on operators.

Splash-proof junction box

The following figure shows the splash-proof junction box, which has the following characteristics:

1) The cover 4 of the junction box is fixed on the junction box body 1 with two screws (that is, the screws will not fall after the cover is opened);

2) The cover is bolted with chain 5. When the cover is opened, the chain is bolted so that the cover will not fall;

3) The seal between the cover and the junction box body is made of heat-resistant black rubber as a sealing ring;

4) The outlet hole is sealed with black rubber as the sealing ring 8, and then the outlet bolt 7 is pressed to clamp the connecting wire;

The splash-proof performance of the splash-proof junction box should withstand the test of artificial rain sputtering at a rainfall of 5 mm/min and a 45° angle to the horizontal for 5 minutes. During the test, the thermocouple and thermal resistance rotate along the longitudinal uranium. Then open the junction box cover for observation, no water can penetrate into the interior,

The thermocouple and thermal resistance products of the junction box with splash-proof performance can be used in the scene where water vapor splashes or is relatively humid or dusty.

Waterproof junction box

The figure below shows the waterproof junction box. Its structure is compared with the splash-proof junction box. The structure of the other parts is the same except that the cover 2 and the junction box body 1 are connected differently.

The structural feature of the waterproof junction box is that the cover 2 of the junction box and the junction box body 1 are connected by threads. Relying on the tightening force of the cover and the junction box body, the sealing ring made of heat-resistant black rubber is evenly pressed on the entire circumference, so that even if there is serious water vapor or harmful gas, it will be sealed well. Block it so as not to penetrate into the junction box.

The waterproof performance of the waterproof junction box should withstand a distance of 5 meters. Use a faucet with a nozzle diameter of about 25 mm to spray water in any direction. The water pressure before the nozzle outlet is not less than 2 kg/cm. The test lasts for 5 minutes. Open the junction box after the test Observe the cover, and no water should penetrate into the junction box.

The thermocouple and thermal resistance of the junction box with waterproof performance are suitable for the scene where water is often sprayed. For example, the equipment installed in moldy weather or indoor equipment needs to be cleaned frequently. In addition, the waterproof junction box is easy to assemble and disassemble. After the cover of the junction box is opened, it is bolted to the junction box body with a chain, so it will not be lost. These are more suitable for high-altitude equipment.

Other categories

Explosion-proof junction box

The explosion-proof junction box has two types: flameproof type and increased safety type. According to its wiring method, it can be divided into two types: steel pipe wiring and cable wiring. The steel pipe wiring is equipped with pipe joints to facilitate the connection between the steel pipe and the junction box; the compression nut is used for the cable wiring. The explosion-proof wiring basin is equipped with a wiring socket made of melamine slate and arc resistant plastic. Each port of the junction box is equipped with rubber gaskets, blocking plates, metal washers and compression nuts (or pipe joints). After the wire is introduced, the nut or the pipe joint must be tightened to meet the requirements of sealing and isolation.

Features of explosion-proof box:

1) Cast aluminum alloy shell, surface spraying, beautiful appearance. The explosion-proof and anti-corrosion series are made of glass fiber reinforced unsaturated polyester resin molded shell. Or stainless steel welding forming;

2) When opening the cover, you only need to loosen 1/3 of the bolt, and then turn the cover clockwise by 10° to open, which can achieve the effect of not losing the bolt and opening the cover quickly;

3) There are many ways and specifications for the inlet and outlet ports;

4) The thread of the inlet and outlet can be specially made;

5) Steel pipe or cable wiring;

6) The explosion-proof junction box meets the requirements of GB3836-2000, IEC60079, GB12476.1-2000, and IEC61241 standards.

Solar Junction Box

The solar cell module junction box is composed of solar cell modules

Explosion-proof junction box

Explosion-proof junction box

The connector between the solar cell array and the solar charging control device is a cross-domain comprehensive design integrating electrical design, mechanical design and material science. The solar cell module junction box is very important in the composition of the solar module, and its main function is to connect the power generated by the solar cell with the external circuit. The junction box is glued to the back plate of the component through silica gel, the lead wires in the component are connected together through the internal wiring in the junction box, and the internal wiring is connected with the external cable to make the component and the external cable conduction. There are diodes in the junction box to ensure that the components can work normally when the light is blocked.

The main characteristics of the solar cell module junction box:

1) The shell is produced with imported high-grade raw materials, which has extremely high anti-aging and ultraviolet resistance;

2) It is suitable for long-term outdoor use under severe environmental conditions, and the use time is more than 30 years;

3) 2 to 6 terminals can be built-in according to needs;

4) All connection methods adopt quick-connect plug-in connection.

Requirements

Generally, the junction box is composed of a box cover, a box body, a terminal, a diode, a connecting wire, and a connector.

The requirements for use are as follows:

1) The shell must have strong anti-aging and ultraviolet resistance;

2) Meet the requirements for use under harsh outdoor environmental conditions;

3) The self-locking function makes the connection method more convenient and firm;

4) It must have a waterproof seal design, scientific insulation protection against electric shock, and better safety performance;

5) The wiring terminal should be installed firmly and have good weldability with the bus;

6) The main function of the diode is the one-way conduction function;

7) Connectors and connecting wires: with good insulation performance, male and female plugs with self-locking function make the solar panel and electrical connection more convenient and reliable.

Installation of junction box

Installation of wire box under cast-in-situ floor

As shown in the figure, there are three installation methods for the installation of the junction box under the cast-in-situ floor: set the terminal junction box connection, set the intermediate junction box connection, and set the branch line box connection. Among them, the terminal connection method has only one outlet, while the indirect method has two outlets, and there are 4 outlets in the branch box connection.

The junction box is installed on the beam side

As shown in the figure, the junction box is installed on the beam side, and the cables need to be tied on the steel bars when entering the floor.

The junction box is installed in the wall

As shown in the figure, the same cables need to be bound and fixed after they are led out from the junction box.