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Introduction of various protection standards when the busway is used in the open air

  • Categories:Zhongrui News
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  • Time of issue:2019-05-28 14:06
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(Summary description)In engineering, it is also common to encounter substations in separate buildings or in the open air. At this time, the substation and the user need to use the cable or busway for power transmission and distribution, and the cable is laid into the power building through the cable trench or directly buried. However, for large-capacity users (400A or more), it is very difficult to use cables because the cross-sectional area of ​​the cables is not enough. In the past, double-split or even three-ply cables were used to solve this problem. Cable experts now oppose this solution because the contact resistance existing in the cable connection will seriously affect the current balance of the multi-ply cable.

Introduction of various protection standards when the busway is used in the open air

(Summary description)In engineering, it is also common to encounter substations in separate buildings or in the open air. At this time, the substation and the user need to use the cable or busway for power transmission and distribution, and the cable is laid into the power building through the cable trench or directly buried. However, for large-capacity users (400A or more), it is very difficult to use cables because the cross-sectional area of ​​the cables is not enough. In the past, double-split or even three-ply cables were used to solve this problem. Cable experts now oppose this solution because the contact resistance existing in the cable connection will seriously affect the current balance of the multi-ply cable.

  • Categories:Zhongrui News
  • Author:
  • Origin:
  • Time of issue:2019-05-28 14:06
  • Views:
Information
In engineering, it is also common to encounter substations in separate buildings or in the open air. At this time, the substation and the user need to use the cable or busway for power transmission and distribution, and the cable is laid into the power building through the cable trench or directly buried. However, for large-capacity users (400A or more), it is very difficult to use cables because the cross-sectional area of ​​the cables is not enough. In the past, double-split or even three-ply cables were used to solve this problem. Cable experts now oppose this solution because the contact resistance existing in the cable connection will seriously affect the current balance of the multi-ply cable.
 
Substations of industrial and mining enterprises are usually located in separate buildings, but due to their large capacity, bus trunking is generally used for transmission and distribution. During construction, the busway is from one building to another, some are protected by a gallery, and some are directly open-air, both of which should be considered outdoor.
 
In order to prevent wind, sand, rain and snow from entering the busway for outdoor use, it is necessary to protect the casing. Then, how is the enclosure protection level determined? Is it safe to take IP54? Further analysis is required.
 
Firstly, the meaning of IP54 is analyzed. According to GB 4208-1993 "Shell protection level (IP code)", the first characteristic number "5" indicates that dust cannot be completely prevented from entering, but the amount of entry cannot reach the extent that it hinders the normal operation of the equipment; The two-digit characteristic number "4" means: splash-proof water, splashing water in any direction has no harmful effects.
 
If the IP54 protection grade busway is used outdoors, it is not afraid that dust will enter the casing, but it will be afraid of rainwater entering the casing, which will greatly reduce the insulation performance of the busway. The busway used outdoors is not only afraid of rain, but also afraid of moisture, even if the busway used indoors is afraid of moisture. In a project such as the sea, the busway for the indoor basement, because the moisture enters the casing, so that the insulation performance of the busway does not meet the design and use requirements.
 
Although IP54 is splash-proof, it does not prevent heavy rain from invading the housing of the busway.
 
For coastal areas and factories with corrosive gas pollution, corrosion of corrosive gases such as salt spray should also be considered. Therefore, steel shell busbars cannot be used, because steel shells will corrode when used outdoors.
 
For the above reasons, IP 6 8 grade busbars should be used outdoors. The meaning of IP 6 8 is: the first digit “6” indicates dust density and no dust entering; the second digit “8” indicates anti-diving effect, which allows the busway to be immersed in water for a long time.
 
To achieve IP54, the steel shell is used to seal the design to achieve the purpose; for IP68, the steel shell seal is not sealed.
 
For the outdoor busway, the influence of low temperature on the insulating material of the busway should also be considered. It is usually required that the insulating material can work for a long time without being cracked in the environment of -35 °C, and the busbar groove with no metal casing should also have the function of preventing ultraviolet aging.
 
The resin-cast busway can easily meet the requirements of IP68. For example, Shanghai Gaoqiao Shipbuilding Co., Ltd. is used for the busway in the dock and dock construction, and its water resistance is required. Therefore, the Yutai Group's fully enclosed resin cast busway has an enclosure rating of IP 68.7, which is very good in performance and has undergone long-term construction tests. Therefore, the second phase of the project still uses resin cast busway.
 
In the current construction, the busbar cannot be cast with ordinary resin because the insulation performance of the ordinary resin drops sharply when the temperature rises above 80 °C. JD's JDR busway is made of a composite resin that maintains the standard insulation resistance at 100 °C. This composite resin is a special resin that cures at room temperature, resists 6 joules of impact, and has UV aging resistance, and can work for a long time in a low temperature of -40 ° C environment.
 
The JDR fully enclosed resin cast busbar has no metal casing and can be used not only in corrosive environments, but also in cable trenches or even buried.

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