Fluke Fluke 4325170 Manual Do Utilizador

22 

As all four pylon stubs are connected to the foundation earth of the pylon, the measuring 
current I

meas

 is divided into five components according to the present resistances 

involved. 

One part flows via pylon construction to the overhead earth wire and further to the 
parallel circuited pylon earthing resistances.  

The other four current components (I

1

4

) flow via the individual pylon foots. 

The addition of all currents result in a current I

E

 going through the earthing resistance, for 

example, the resistance of the "composite" earth electrode to the soil. 

If the current transformer is fixed to each pylon stub, one after the other, four resistances 
have to be measured which show a behavior inversely proportional to the corresponding 
current components I

1

4

. The feeding point of the measuring current is to be left 

unchanged to avoid a change in the current distribution. 

Accordingly, these equivalent resistances are displayed as: 

=

 

Therefore the earthing resistance R

E

 of the pylon is determined as a parallel circuit of the 

individual equivalent resistances: 

4

3

2

1

1

1

1

1

1

+

+

+

=

 

1.  Turn central rotary switch to position “R

E

 3pole" or R

E

 4pole". The instrument 

is to be wired according to picture and messages on the display. 

2.  Apply current transformer to the pylon stub. 

3. Push 

START. 

Now a fully automated test sequence of all relevant parameters like auxiliary earth 
electrode, probe and earth electrode resistances is implemented and finishes with the 
display of the result R

E

.