What about the way the cable is laid?
1. If there is no major impact, it is ok to make the laying.
2. If there may be some relatively large impact, but the intensity can be controlled in a certain range, can be considered to be buried.
3. If the external force is larger, you need to use the protective sleeve, which can be set locally (for example, by road).
The advantages and disadvantages of laying the cable directly
Advantages: convenient installation, saving materials and labor,
Disadvantages: the maintenance of inconveniences, if you want to maintain, you need to dig up the cladding, only suggest to use in the place that does not consider maintenance, or can accept this kind of maintenance way. When buried, usually need to cushion the yellow sand.
Problem 1 buried cable grounding, how to find fault point?
Answer: use the patrol cable tester.
Question 2. Does the cable need to be cable well?
The problem is added: the cable laying in the factory shall be buried by the armored cable, or whether the electric cable well shall be added to the distribution room of the plant. Will the municipal 10KV cable be added to the site?
Answer: cable in 6 and below do not have cable well, cable more Wells, facilitate replacement, add cable. The municipal 10KV cable shall enter the factory area without any cable well and shall be buried directly to the high voltage distribution cabinet from the end pole.
Question 3 how will the temporary cable of the site be laid?
Problems added: unit newly built workshop, construction transformer and high voltage line distance center far away, because it is the steel structure workshop, cannot take the overhead line, in order to avoid conflict and steel structure installation, can only use low voltage cable from the transformer to the construction site of the primary distribution box, and then assigned to the various construction unit of secondary distribution box, is there how low voltage cable laying? Is it buried directly or directly on the ground?
Answer: do not apply directly to the ground. This low - voltage cable is buried directly.
What should I pay attention to through the pipe laying?
Under what circumstances?
The cable pipe laying is easier to maintain and increase the line in the later stage than the direct buried. The cable that is laid in the pipe can consider some spare tube to prepare for future line maintenance and enhancement.
1. When the pipe is laid, it is necessary to consider setting up the cable well when the line Angle is larger or the line distance is longer.
2. With less cable and smaller diameter, the cable hand well can be adopted;
3. In case of large cable and large diameter, it is necessary to consider the installation of cable man well. The cable well can be done according to the atlas. In addition to the collection method, many small pass Wells can be directly brick or concrete pouring, at this time, the water seepage hole should be considered at the bottom.
4. The pipe of tube is now more and more of cast iron pipe, steel tube, polyethylene pipe, nylon pipe, carbon pipe, etc., can be selected according to need. Note the influence of eddy current in single core cable.
What should I pay attention to?
Under what circumstances?
The pipe lines are mainly used in the area of more lines, which are more convenient and save the material.
Question 1. Is there a line of pipe, a cable, or a multi-cable pipe?
A: only one cable should be worn per tube. Besides power plants, substations and other places of importance for all circuits or an electric motor the same device of low-voltage motor all circuits, can be worn on each tube in not more than three root power cable or control cable. See the p325 GB50217-2007. 4.4.
Question 2. The pipe laying depth is not enough. What shall we do?
Question: how to make cable pipe laying in less than 1m thickness? Below is the basement, the basement ceiling is only 70, 80 cm thick, the well depth is 1.3 meters?
Answer: if there is no traffic area, the buried depth is not less than 0.5 m (the cable specification requires 0.5 m, and the people's regulation is 0.7 m, which is based on the cable specification). If more vehicles are used, protective boards can be added to the drain. Or use thick-walled steel pipe to lay or use cable trench. If the basement roof covering only 70 ~ 80 centimeters, well depth to do 1.3 m of roof fall plate, but the meaning is not big, because the cable pit drainage problem difficult to solve, and few pay attention to.
Question 3. Power grid and weak current?
Problems added: there is a factory outside, a dozen low-pressure high voltage cable, and weak current cable television, telephone, network, high voltage cable is more than eight root, cannot be used directly buried, I adopted the exhaust pipe laying. But now there is a problem, which is that the weak current is also laid by the pipe, so the power tube and the weak tube can be in all the time?
Answer: try not to come together, make small municipal as far as possible to set the strong and weak tube on the side of the road. If there is an occasional crossover, it is recommended to apply according to standard spacing. You can refer to the atlas, such as the underground communication cable, such as the type 05x101-2.
Question 4. External cable concrete pipe laying?
When drawing a general picture, party a shall require all outdoor cables to be installed in the concrete piping. A review of the atlas (94D164) has the following questions:
1. Due to the influence of the other pipelines on the site, the cable discharge tube is not in the line well except the straight-line well, and the rest can not be sized according to the size shown in the atlas.
What's the solution?
2. The problem of drainage in manhole Wells. According to the people's regulation, manhole is set up in the water pit, but not know how to concentrate the drainage.
3. The spacing of manhole Wells is 150m according to the specification, and the atlas is 50m. I don't know which one to take, there are other rules.
4. Is there any other picture set that can be referenced, besides the standard well, can you design the shape and size of the well?
5. What should be paid attention to during design and construction?
Answer: 1. Design a non-standard well as needed;
2, the drainage inside the hole, if conditional set of drainage pumps, drainage pumps should be set, if there is no way to set the drainage pump, set the spillway hole at the bottom of the sump, don't use concrete block, let the water permeability can also naturally, but depends on the local groundwater level;
3. The spacing of manhole Wells is usually considered according to 50 ~ 70;
4. In the opinion of the individual, the distribution of small municipal services shall not be required to do well in accordance with the drawing set.
5. The concrete exhaust pipe has not been done, but please refer to gb50217-2007p325.
What should be noticed in cable trench?
Under what circumstances?
The cable trench should be noted that different voltage grade cables should be divided into different brackets, and the cable trench should pay attention to the drainage measures. And consider measures to prevent small animals such as mice from entering.
Question 1 how many cables need to be laid by cable?
Answer: according to "measure 20096.10 8 the following proposal USES direct burial, 8 ~ 12 root proposal USES drain tube, 12 ~ 18 root suggest to use cable channel, 18 above suggest use cable tunnel." All of these are suggested, and the actual engineering reference can be used, not so fixed. As for cable trench and cable tunnel, it is not the difference between the root number and the maintenance and importance.
Mainly is to look at the engineering conditions, factors such as environmental characteristics and cable type number, and meet the reliable operation, easy to maintain, and the requirements of technical economic and reasonable choice, not sure whether there is a mandatory index requirements. The specific programme is determined to refer to the relevant content of gb50217-2007p285.
Question 2. How is the cable flow measured in cable trench?
Answer: netizen 1: according to the bridge frame to consider, considering that the bridge is in the air, and the cable trench has the cover plate, to reduce the coefficient of capacitance 0.96.
2: (carrying capacity by the correlation coefficient can reference GBT16895.15-2002 the building electric installation part 5 section 523 wiring system carrying capacity ", personally, according to the coefficient of ladder to consider more appropriate.)
Question 3: can the bus be laid down in the cable trench?
Answer: there is no requirement, in cable trench depth is according to the number of the number of cable and cable types you to decide, such as control cables, low voltage power cable, high voltage power cables, general will set up three layers, each layer spacing between 250 ~ 300, this determines the height.
Question 4. Do the cables need to be cable well?
Problems added: engineering, high-rise hospital, to save money, choose oil-immersed transformer is installed outdoors, from the building 15, including 6 m road (middle) meters underground low-voltage switchgear room is located in the hospital, in order to save investment, I want to use bus duct (3000 a) load flow along the cable trench to building house laying underground substation, is it possible?
A: it should be possible to adopt intensive bus lines that meet the corresponding IP level requirements. For example, Siemens has a busbar that can be laid underwater. However, the cost of using the dense bus line will be higher, and it needs to be taken into consideration that it is better to choose the dry change and adopt the bus. The personal suggestion is to use the dry type transformer and put it in the room. The maintenance work will be smaller and the failure rate will be lower.
Question 5 how many cables can be laid in the cable trench without a bracket?
Answer: generally is to want the bracket, if do not have the bracket, the cable maintenance of cable trench will be more troublesome. If the project is small and the number of cables is small, it will be ok, but the heat condition will be less, and if there is water in the trench, it will affect the cable as well.
Question 6. Can the cables share the cable trench?
The problem is added: outdoor cable trench, 1200mm groove width, two side supports, 10KV high-voltage cable on one side, 1KV low voltage cable and control cable on the other side, is it consistent with the specification? What should I pay attention to?
A: it can be laid in a common cable trench. The requirements of gb50217-2007p245. 1.3 and 5.1.4 are required.
Question 7. What is the distance between the cable trench and the road?
Answer: this is mainly to consider the force of the cable trench cover plate, if the force has no problem, also have no problem. Usually set on a sidewalk or where a motor vehicle does not pass.
Question 8 cable should be used in cable trench?
The technical measure says: when the cable is laid in the cable trench or in the cable tunnel, the cable should be considered for the type of plastic sheath with anti-ant and rodent protection. But the specification doesn't seem to make it clear. Can we not have an armored one?
Answer: the direct buried cable does not have the mandatory requirement to use the armor, the cable trench is even less. According to different environmental requirements not the same, (if this area rat activity is rampant, suggest armor) general has no mandatory requirement.
Question 9. What is the minimum distance between the power cable and the weak current cable in the cable trench and the layering in the same side bracket?
Answer: the cable with weak electricity is separated by metal plate, and the metal plate is grounded at the same time! Best of all, the upper bracket is made of iron plate (or metal tray), the iron plate is grounded, and the weak cable is placed on the iron plate (in the slot box).
According to gb50217-20075.1.3: the voltage grade shall be installed in the order of the power cables, the power cables, the power cables and the signal cables and the communication cables of the cables and cables. Can be determined according to gb50054-2011 table 7.6.23.
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