接地电阻的计算

工频接地电阻计算,,,,,,,

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1、垂直接地体的接地电阻R的计算：当l>>d时，R=ρ/(2πL)×(ln(4L/d)-0.31),,,,,,,

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,ρ,L,b,b1,b2,d,R

对于扁钢,2,10,0.04,,,0.02,0.232194346

对于角钢,500,10,3,0.05,0.05,0.042216853,52.10043982

圆钢（管）,1000,100,,,,0.1,12.71345484

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1.1、土壤电阻率ρ的计算,,,,,,,

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,R,L,b,b1,b2,d,ρ

对于扁钢,30,1,0.16,,,0.05,46.26688794

对于角钢,10,2,3,0.05,0.05,0.042216853,25.45407285

圆钢（管）,10,1,0.05,,,0.05,15.42229598

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1.1.1、当角钢为0.05×0.05×1m长和0.05×0.05×2m长时的电阻率ρ：,,,,,,,

k角=2πL/(ln(4L/d)-0.31)ρ=k角×R,,,,,,,

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,R,L,b1,b2,d,K,ρ

对于角钢,10,1,0.05,0.05,0.042216853,1.48070248,14.8070248

对于角钢,10,2,0.05,0.05,0.042216853,2.545407285,25.45407285

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当角钢为0.05×0.05×1m长时的电阻率ρ为：,,,,14.8070248,,,

当角钢为0.05×0.05×2m长时的电阻率ρ为：,,,,25.45407285,,,

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1.1.2、当圆钢为d=0.08×1m长和d=0.08×2m长时的电阻率ρ：,,,,,,,

k圆=2πL/(ln(4L/d)-0.31)ρ=k圆×R,,,,,,,

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,R,L,d,K,ρ,,

圆钢（管）,240,100,0.16,83.57681056,20058.43453,,

圆钢（管）,10,2,0.08,2.924214747,29.24214747,,

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当圆钢为0.08×1m长时的电阻率ρ为：,,,,20058.43453,,,

当圆钢为0.08×2m长时的电阻率ρ为：,,,,29.24214747,,,

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其中：ρ——土壤电阻率(Ωm)；,,,,,,,

L——垂直接地体的长度(m)；,,,,,,,

d——垂直接地体的等效直径（m）。,,,,,,,

对于扁钢d=b/2，b为扁钢宽度；,,,,,,,

对于角钢d=0.71×(4√(b1×b2×(b12+b22))，b1、b2为角钢边长；,,,,,,,

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,,,,图为：垂直接地体,,,

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2、不同形状水平接地体的接地电阻R的计算：R=ρ/(2πL)×(ln(L2/(hd))+A),,,,,,,

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,ρ,L,h,d,A,R,

,2000,5000,1,0.03,5.65,1.668213011,

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h——水平接地体的埋设深度(m)；,,,,,,,

d——水平接地体的直径或等效直径(m);,,,,,,,

A——水平接地体的形状系数。,,,,,,,

水平接地体的形状系数可采用下表所列数值：,,,,,,,

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形状,,,,,,,

A,5.65,3.03,1,0.89,0.48,0,—0.18—0.6

3、以水平接地体为主，且边缘闭合的复合接地体，其接地电阻的计算：,,,,,,,

R=(0.22-0.007L1/L2)×ρ/(√(L1×L2))×(1+B)+ρ/(2πL)×(LN((L1×L2)/(9hd))-5B)B=1/(1+4.6h/(√L1×L2)),,,,,,,

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ρ,L1,L2,d,L,h,B,R

1000,400,200,3,700000,20,0.754563722,1.278162575

其中：L1、L2——分别为地网水平投影长度、宽度(m)，L1、L2≤8；,,,,,,,

L——接地体的总长度，包括垂直接地体在内(m)；,,,,,,,

d——水平接地体的直径或等效直径(m)；,,,,,,,

h——水平接地体的埋设深度(m)。,,,,,,,

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