The latest treatment scheme for the condensation of 10 thousand volt distribution network lines of r

There are usually several methods for condensation prevention and control of ring main units: natural ventilation method, forced ventilation (exhaust) method, electric heating method, desiccant dehumidification and other methods, but the dehumidification effect is unsatisfactory, the specific reasons are as follows:

1.Natural ventilation methodThe natural ventilation method is mainly to optimize the basic design of the ring main unit, block the water vapor from entering the cable room, raise the height of the ring network switch cabinet foundation to the ground, install shutters on the foundation to make the internal air and external air form an effective circulation, reduce the internal humidity of the space below the ring network switch cabinet, so that the humid air no longer enters the cable room, and the ambient humidity does not work when the ambient humidity is large, which is easy to cause dust and dirt to enter and cannot achieve the purpose of moisture prevention.

2.Forced ventilation Forced ventilation The exhaust method is to install an exhaust fan at the bottom of the box cabinet and an exhaust fan on the top side to accelerate the air circulation inside the cabinet, so that the air inside the cabinet has been in an unsaturated state, destroying the condensation formation conditions. The disadvantage is that this method needs to configure equipment such as fans, and noise will be generated during operation, and the internal space of some cabinets is limited at the same time, and it is difficult to install.

3.The electric heating method is to install an aluminum alloy heater (generally 150W) in the cable room and circuit breaker room under the cabinet to increase the internal gas temperature of the cabinet through heating, reduce the relative humidity, and prevent condensation from forming. However, due to the tight closure in the box, the steam cannot be discharged out of the box in time after heating, which will make the place with condensation more and more serious, and the place with less condensation will also increase the speed of condensation.

If this goes on for a long time, it will cause serious consequences, such as rust and mildew of cables and terminal strips, and the service life of the equipment will be greatly reduced. For the terminal box of the substation where the condensation phenomenon is more serious, water droplets may drip on the terminals and a ground fault may occur.

4.The desiccant method uses desiccant to absorb the moisture in the cabinet to avoid the formation of condensation, which is simple and easy to use, but in fact, because its water absorption effect is limited, and the absorbed water is difficult to discharge, the effect is often not obvious, and the maintenance workload increases.

To carry out a long-term and effective method for the moisture in the cabinet, the method used in the major substations is to install intelligent dehumidifiers in the cabinet, such as SEPRI-CS-NL(E) anti-condensation device and SPR-CN-S1 intelligent dehumidifier, which is small in size and can discharge the moisture in the cabinet through the hose. It can also be dehumidified at low temperatures. Realize automation, when the humidity in the cabinet exceeds the standard, it will work automatically.

These are switchgear.

The size of each manufacturer is different, what do you want to do with this.

It is recommended that you use Siemens 8DJH inflatable cabinet, which is cost-effective.

Analysis of the causes of condensation

When the water vapor content in the air is close to the saturated water vapor content at the current temperature, once the air temperature decreases, the water vapor content in the air exceeds the saturated water vapor content at the current temperature, and the water vapor will precipitate on the surface of the inner wall of the equipment at a lower temperature to form condensation. Therefore, there must be two conditions for the formation of condensation: first, the air has a high relative humidity; Second, the temperature of the equipment where condensation occurs is always lower than its ambient temperature.

Common condensation solutions

1 Natural ventilation method

The natural ventilation method is mainly to optimize the basic design of the ring main unit, block the water vapor from entering the cable room, raise the height of the ring network switch cabinet foundation to the ground, and install shutters on the foundation to form effective circulation of internal air and external air, as shown in Figure 1, reduce the internal humidity of the space below the ring network switch cabinet, so that the humid air no longer enters the cable room, so as to effectively solve the problem of condensation.

2 Forced ventilation and exhaust method

Forced ventilation The exhaust method is to install an exhaust fan at the bottom of the box-type cabinet and an exhaust fan on the top side to accelerate the air circulation inside the cabinet, so that the air inside the cabinet has been in an unsaturated state, destroying the condensation formation conditions. The disadvantage is that this method needs to configure equipment such as fans, and noise will be produced during operation, and the internal space of some cabinets is limited simultaneously, and the installation is difficult, and more is the lack of power supply or insufficient power supply capacity inside part of the ring main unit and branch box, so this scheme is more suitable for the anti-condensation treatment of box-type transformer.

3 Electric heating method

The method is to install an aluminum alloy heater (generally 150W) in the cable room and circuit breaker room under the cabinet to increase the gas temperature inside the cabinet through heating, reduce the relative humidity, and prevent condensation from forming. This solution also requires power supply, and PT power supply needs to be configured for ring main unit and branch box equipment.

4 Electric dehumidification

The basic principle of the electric dehumidification method is to generate a low temperature point through semiconductor refrigeration technology, condense the water vapor in the air to this point, and the water droplets are discharged out of the cabinet along the condensation tank and pipe, so as to dehumidify the switchgear. The advantages of semiconductor line dehumidification device are small size, easy to install, low power consumption (about 15W), outdoor solar battery power supply can be considered, no vibration and noise are generated during work, and at the same time there is a good power-saving effect; The disadvantage is that it is expensive, and the dehumidification effect is limited when the humidity in the cabinet is large.

5 Desiccant method

That is, the desiccant is used to absorb the moisture in the cabinet to avoid the formation of condensation, which is simple and easy to use, but the desiccant is easy to saturate, needs to be replaced in time, and the labor cost of maintenance is high, which is mainly suitable for temporary treatment, seasonal humidity is too high, and the power supply can not be obtained.

Distribution station: It is divided according to the voltage level, there are 10kv, 35kv, 110kv, 220kv, 500kv, and the voltage level is converted between these voltage levels, and it is connected by overhead lines and power cables;

Ring main unit: divided into indoor and outdoor, 10kV indoor ring main unit (mainly single interval) is usually summarized into the switch station category, outdoor ring main unit (more common boxes), also called box-type opening and closing, the main purpose is the urban ring network power supply, the inlet and outlet line voltage is consistent;

Cable branch box: also divided into high-voltage branch box and low-voltage branch box, both are mainly used to expand the outgoing circuit, and another application is for the intermediate connection of long cable lines.

According to my limited knowledge and understanding, I will give you a short answer, and I will not ask you to give points:

Cable distribution box: As the name suggests, the cabinet for cable distribution or transfer, x-in-x-out, load distribution or long cable transfer.

Ring main unit: cable distribution box with switch can be controlled remotely.

Opening and closing station: a small unattended substation (distribution station) with a single bus or a single bus segmented primary junction, which is smaller in scale than the distribution station.

Distribution station: 35kV (110kV) into 10kV, divided into several outlets for the substation used by electricity users.

Substation: Voltage conversion station of ultra-high voltage and high voltage level, e.g. from 500kV to 220kV

10kV ring main unit is a power distribution power supply equipment that has been gradually adopted in recent years, its advantages are small size, full insulation, safe and reliable, flexible wiring. The main application is the center of the load-dense distribution lines. The use of ring main unit can first solve the problem of limited outgoing corridors of substations.

The ring main unit can flexibly distribute the lines to different user distribution rooms through its own several in and out of the way. Second, the ring main unit has the characteristics of full insulation and full sealing, safe and reliable operation, no need to build a separate power distribution room, and can be operated outdoors. Reduce construction costs and floor space.

Thirdly, most of the switches of the ring main unit are three-station operation, with mechanical interlocking structure, not easy to misoperate, when the ground knife is closed, lock the operation hole of the interval main switch, and lock the operation hole of the ground knife when the main switch is running. In addition, the door of the cable room can also be locked by mechanical locking, and the door of the cable room cannot be opened when the main switch is running, etc. Now it has become the main power load distribution equipment of the city power grid.

In AC 10kV power distribution systems such as industrial and mining enterprises, residential quarters, ports and high-rise buildings, due to the small load capacity, the high-voltage circuit is usually controlled by load switch or vacuum contactor, and is equipped with high-voltage fuse protection. The system is usually powered by a ring network, and the high-voltage switchgear used is generally customarily called a ring main unit.

When a high-voltage power supply is connected to n transformers.

In the sense of high-voltage ring network, it is a high-voltage branch box, but in the high-voltage of incoming or double incoming lines, there are multiple outgoing lines!

First, the nature is different.

1. Branch box: only used as a cable branch.

2. Ring main unit: a group of transmission and distribution electrical equipment (high-voltage switchgear) installed in a metal or non-metal insulated cabinet or made into an assembled interval ring network power supply unit.

Second, the role is different.

1. The function of the branch box: the cable is tapped/transferred, which mainly plays the role of cable tapping and cable transfer.

2. The function of the ring main unit: the load switch and fuse are adopted, which has the advantages of simple structure, small size, low size, can improve power supply parameters and performance, and power supply safety.

Third, the application is different.

1. Branch box application: branch box is widely used outdoors, with the development of science and technology, there are more and more cable junction boxes with switches. City cables are usually powered by a double circuit. Therefore, some people call the junction box with a switch directly as an outdoor ring main unit.

However, at present, most of these ring cabinets cannot realize power distribution automation. However, manufacturers have introduced outdoor ring cabinets that can automate the distribution network, which has also blurred the line between branch boxes and ring main units.

2. Application of ring main unit: The ring main unit has not appeared for a long time, but it has been widely used. This is mainly due to the newly developed buildings of industrial enterprises and institutions.

From the perspective of power supply and distribution, the small capacity of most of its distribution transformers generally does not exceed 1250kva, long-term stable power supply, and high-voltage switches are not frequently operated.

The main function of the cable branch box is to tap or transfer the cables.

1) Cable tapping. There are many small-area cables on a relatively long distance line, which often causes the waste of cable use, so in the outgoing line to the electrical load, the trunk large cable is often used to go out, and then when it is close to the load, the trunk cable is divided into a number of small-area cables by the cable branch box, and the small-area cable is connected to the load. This wiring method is widely used for power supply such as street lamps in urban power grids and power supply for small users.

2) Cable transfer. On a relatively long line, the length of the cable can not meet the requirements of the line, then it is necessary to use a cable joint or a cable adapter box, usually a short distance when the cable intermediate joint is used, but when the line is relatively long, according to experience, on the cable line above 1000m, if there are multiple intermediate joints in the middle of the cable, in order to ensure safety, the cable branch box will be considered for transfer.

3) branch boxes are widely used outdoors, with the progress of technology, now the cable branch box with switch is also increasing, and urban cables often use double circuit power supply mode, so some people directly call the branch box with a switch outdoor ring main unit, but at present, most of such ring main units can not realize distribution network automation, but the manufacturer has launched the outdoor ring main unit that can be used for distribution network automation. This also makes the boundaries between the cable branch box and the ring main unit begin to blur.

The ring main unit is mainly used to realize double circuit or multi-loop power supply to improve the reliability of power supply. At present, the advanced ring main unit can achieve the automation of distribution network and realize long-distance operation.

Now there are more cable branch boxes in the ring main unit mode, and it is estimated that they will be integrated in the future.

The ring main unit has both incoming and outgoing lines, and the cable branch box is the same, I think the difference should be the power supply mode rather than the incoming and outgoing line mode, the ring main unit can be powered by double or multiple circuits to ensure the reliability of power supply, while the cable branch box does not have the power supply capacity of multiple circuits or double circuits. In addition, the ring main unit can now realize the distribution network automation and remote control, and the cable branch box basically does not have such a function at present (except for the outdoor ring main unit with switch).

The ring main unit is a general term for the high-voltage cabinet that meets the power transmission of the ring network, and the ring main unit is also called the cable branch box with a switch, and usually the cable branch box is without a switch! As the name suggests, ring power supply, in a sense, is to achieve uninterrupted power supply, which plays a great role in promoting the composition of intelligent power grid!

We usually say that the cable is divided into bai

Branch box, divided du branch means by zhi

One becomes multiple, that is, a total cable of dao is divided into multiple genus road outlets through the branch box, and the number of branches of a branch box should not exceed 6 (European style); Ring main unit, as the name suggests, can be powered by the ring network, forming a closed loop, usually double power supply inlet line, multiple outgoing wires; When the 2-way power supply is live, the power supply inlet cabinet can not be closed at the same time, and now most of the ring main unit combination tends to be used more as a cable branch, which is safer to use, but the cost is higher. The cost of the cable branch box is low, a 10kv without a switch 6 branches, the cable branch box is only about 10,000 yuan, and the switch (only with a switch) is about 20,000 yuan; The ring main unit is not, a cabinet as a unit (each unit with a switch PT cabinet except), 6 branches need a day to enter the line 5 sets of outgoing lines, its cost is mostly more than 100,000 (domestic air insulation non-fully enclosed inflatable cabinet). If the imported product** is higher.

Schneider's may be as high as about 500,000.