Earth And Resistivity Measurement; Resistivity Measurement; Earth Measurement - Chauvin Arnoux C.A 6710 Notice De Fonctionnement

6. EARTH AND RESISTIVITY MEASUREMENT

F
The earth can be measured using the following instruments:
- C.A 6115N
- C.A 6421/23/25
- MX 4600
Resistivity measurements are only possible with the C.A 6425.
6.1

Resistivity measurement

Connect terminals E, ES, S and H (previously X, Xv, Y and Z) of the measuring instrument to the corresponding terminals on the
demo case which simulate rods stuck in the ground. These measurement terminals must be disconnected from the earth bar (F)
just above.
Activate the measurement which must correspond to the 10 Ω resistance R (see drawing above).
The resistivity of a soil in W.m, at a depth of (¾ of the distance between rods) can then be obtained using the formula:
To simulate difficult measurement conditions, you can vary the resistance of the E, ES, S and H measuring rods.
6.2

Earth measurement

Method 1:
Connect terminals E, S and H (previously X, Y and Z) of the measuring instrument to the corresponding terminals on the demo
case which simulate rods stuck in the ground. The demo case terminals must be disconnected from the building's earth bar (F).
Activate measurement. The value of the earth resistance E of the building can be modified between 1 W and 2200 W using a
switch.
The value of the resistance of the auxiliary rods S and H can also be modified to simulate difficult measurement conditions.
Method 2:
Certain multi-function testers offer earth measurement using a slightly different method. This is the case with the C.A 6115N.
The measuring instrument must be connected to the network with the power on via a 2P+E mains socket.
It is then already connected to the earth to measured, E. The instrument must then be connected to an auxiliary rod, S, with the 3rd
point H required for correct earth measurement being the earth of the distribution transformer.
So this is a measurement using the «classic principle» (injection of current between E and H, measurement of voltage between E
and S, calculation of R) but all you have to do is set up one rod (S) and connect up to a network voltage.
Method 3: MX 4600
- Use the cable fitted with a mains plug to a 2P+E socket on the demo case.
- On the MX 4600, select the nominal sensitivity of the differential device to avoid triggering it.
- Activate measurement and read off the earth resistance result.
§ 6.1 Resistivity
Figure N°5
r p
= 2 x x distance between rods (m) x R
(the distance between the rods cannot be simulated)
§ 6.2 Earth
(method 1)
22
PR2
§ 6.2 Earth
(method 2)