建筑物內橋架可以獨立假設，可以附設在各種建(構)筑物和管廊支架上，應體現結構簡單，造型美觀、配置靈活和維修方便等特點，那么您知道電纜橋架的脹縮問題以及接地規定是怎樣的嗎？

The cable tray in the building can be assumed independently and can be attached to various buildings (structures) and pipe gallery supports, which should reflect the characteristics of simple structure, beautiful appearance, flexible configuration and convenient maintenance. Do you know the expansion and contraction problems of cable tray and the grounding regulations?

電纜橋架的脹縮問題

Expansion and contraction of cable tray

由于環境溫度變化，鋼質電纜橋架會出現熱脹冷縮的現象。室外橋架受溫度影響較大例如環境高溫度為40℃，低溫度為-20℃，則電纜橋架的大收縮量按下式求得：

Due to the change of ambient temperature, the steel cable tray will expand with heat and contract with cold. The outdoor cable tray is greatly affected by temperature. For example, the high temperature of the environment is 40 ℃, and the low temperature is -20 ℃, then the large shrinkage of the cable tray is calculated according to the following formula:

Δt=11.2×10-6×60deg(度)×1000mm

Δ t=11.2 × 10-6 × 60Deg (degree) × 1000mm

由此得出結論：

It is concluded that:

溫差為60℃時，Δι=0.672mm/m

When the temperature difference is 60 ℃, Δι= 0.672mm/m

溫差為50℃時，Δι=0.560mm/m

When the temperature difference is 50 ℃, Δι= 0.560mm/m

溫差為40℃時，Δι=0.448mm/m

When the temperature difference is 40 ℃, Δι= 0.448mm/m

工程設計中直線段電纜橋架應考慮伸縮接頭，伸縮接頭的間距建議按以下取定：

Expansion joints shall be considered for cable trays in straight sections in engineering design, and the spacing of expansion joints is recommended to be determined as follows:

當溫差為40℃時為50m;

50m when the temperature difference is 40 ℃;

當溫差為50℃時為40m;

40m when the temperature difference is 50 ℃;

當溫差為60℃時為40m;

40m when the temperature difference is 60 ℃;

山東電纜橋架的接地規定

Shandong cable tray grounding regulations

根據規范的有關規定，鍍鋅電纜橋架進行良好的接地。

According to the relevant provisions of the specification, the galvanized cable tray shall be well grounded.

(1)鍍鋅電纜橋架直接板每個固定螺栓接觸電阻。(電工天下www.dgjs123.com)

(1) Contact resistance of each fixed bolt of galvanized cable tray direct plate. (electrician world www.dgjs123.com)

應小于0.005Ω，此時電纜橋架可作為接地干線(噴粉電纜橋架不宜作接地干線)，每個電纜橋架的電阻值可按下式計算：

It should be less than 0.005 Ω. At this time, the cable tray can be used as the grounding main line (the powder sprayed cable tray should not be used as the grounding main line). The resistance value of each cable tray can be calculated according to the following formula:

r=ρ·L/S

r= ρ· L/S

式中：ρ=15×10Ω-6/cm(20℃)；

Where: ρ= fifteen × 10Ω-6/cm(20℃)；

L=長度按100mm計算；

L= length is calculated as 100mm;

S=截面積cm2。

S= sectional area cm2.

(2)梯架于托盤的單位電阻值見表2。

(2) See Table 2 for the unit resistance value of ladder and tray.

表2梯架于托盤的單位電阻值

Table 2 unit resistance value of ladder to tray

(3)電纜槽的單位電阻值見表3

(3) See Table 3 for the unit resistance value of cable tray

(4)當電纜橋架安裝連接程整體后，每根梯邊(或每個電纜槽)的電阻為：R＝L(r＋1/3r’)

(4) When the cable tray is installed with the whole connection process, the resistance of each ladder side (or each cable tray) is: r = l (R + 1/3r ')

式中：

Where:

R--梯邊，即（電纜槽）全長總電阻（mΩ）；r--梯邊單位長度電阻（mΩ/m）；r’--直接板固定螺栓接觸電阻。

R -- ladder side, that is, the total resistance (m Ω) of the whole length of (cable trough); R -- resistance per unit length of ladder edge (m Ω /m); R '-- contact resistance of fixed bolt of direct plate.

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