NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
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NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
Author: Noyafa–Cable Length Tester
Special attention should be paid to the laying of cable trenches. Cables with different rated voltages should be divided into different support frames. The cable trench itself should pay special attention to the specific measures of drainage pipes. And take into account the specific measures to prevent the entry of animals such as mice. I believe that many friends should pay special attention to the laying of cable trenches. Cables with different rated voltages should be set to different support frames. The cable trench itself should pay special attention to the specific measures of drainage pipes.
And take into account the specific measures to prevent the entry of animals such as mice. I believe that many friends have different problems with cable laying. Here, the cable routing instrument manufacturer will conduct a simple analysis. Question 1: How many cables need to be laid in cable trenches? Answer: According to“Measures 2009 Section 6.10 It is recommended to use direct burial for less than 8, 8 to 12 are recommended to use pipe, 12 to 18 are recommended to use cable trenches, and more than 18 are recommended to use cable tunnels.
”These are all suggestions, just connect with the actual engineering reference, not so fixed. As for cable trenches and cable tunnels, it is not the difference in the number of cables, but the difference in maintenance and importance. It mainly depends on factors such as engineering conditions, environmental characteristics, and the number of cable types, as well as the selection to meet the requirements of reliable operation, easy maintenance, and technical and economical rationality. It is uncertain whether there are mandatory index requirements.
The specific scheme can be determined by referring to the relevant content in Section 5.2 of GB50217-2007 P28. Question 2: How to calculate the current carrying capacity of cables laid in the cable trench? Answer: Netizen 1: (Consider the laying of the bridge, considering that the bridge is in the air and there is a cover plate in the cable trench, the derating factor is 0.96.) Netizen 2: (For the correlation coefficient of current carrying capacity, please refer to GB T16895.15-2002 "Electrical Installations of Buildings Part 5 Section 523 Wiring System Current Carrying Capacity". Personally, I think it is more appropriate to consider the coefficient of the ladder frame.
) Question 3: Is there any requirement for the depth of the cable trench for laying high-voltage cables? Answer: There is no requirement. The cable routing instrument manufacturer points out that the depth of the cable trench is determined according to the number of cables and the number of cable types. For example, if there are control cables, Low-voltage power cables and high-voltage power cables are generally set up with three layers, and the spacing between each layer is generally 250~300, which determines the height. Question 4: Can the bus duct be laid along the cable trench? (Supplementary question: In the first project, a high-rise hospital, to save money, choose an oil-immersed transformer to install outdoors, 15 meters away from the building (including a 6-meter road in the middle), and the low-voltage distribution The power room is located in the underground of the hospital. In order to save investment, I want to use the bus duct (current-carrying 3000A) to lay it along the cable trench to the underground power distribution room of the building. I don’t know if it is feasible?) Answer: Use the dense bus that meets the requirements of the corresponding IP level It should be possible, for example, Siemens has busbars that can be laid to work underwater. However, the cost of using dense busbars will be relatively high. It is necessary to comprehensively consider which is better to use dry transformers or busbars. Personally, it is recommended to use dry-type transformers and put them indoors.
The maintenance workload will be smaller and the failure rate will be lower.
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