Specifications

382357‐EU‐ENV2.42/13
7
MeasurementPrinciples
Typicalmulti‐groundeddistributionsystem

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




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Iftheparallelgroundresistances,
R
1
,R
2
,R
3
,etc,uptoR
n
arecombined
asR
eq
,thenonlyR
g
andR
eq
are
leftinthecircuit



Ifaconstantvoltageisappliedtothecircuit,thefollowingequationapplies:
eqg
RR
I
V

where:
ni
R
R
i
eq
,...2,1,
1
1




IfR
g
andR
1
,R
2
,R
3
…R
n
,areapproximatelythesame,andnislarge(200,forexample),thenR
eq

willbemuchlessthenR
g
andmaypossiblyapproachzero.
Example:
IfR
g
andR
1
,R
2
,R
3
…R
n
areall10respectivelyandn=200,thenR
eq
bycalculationequals:


 05.0
10
1
...
10
1
10
1
1
eq
R

geqg
RRR
I
V
 05.1005.010 
V
I
R
eq
Rg