Principle Of Measurement - Chauvin Arnoux C. A 6410 Notice De Fonctionnement

PRINCIPLE OF MEASUREMENT

The diagram below of the principle of measurement illustrates the general case of
measurement of a loop resistance consisting of:
- the ground rod Rx
- the Earth
- n ground rods
- a guard wire looping together all these earths
- The generating winding of the clamp develops an AC voltage with a constant
level E.
- The current measurement winding in the clamp has the value I = E/R
Knowing E set by the generator and I measured, we can deduce R
(value displayed on the clamp).
- More generally, this principle makes it possible to find defective earths. In fact, the
loop resistance is composed of:
R (value to be found)
x
R (value normally very low less than 1 W ).
earth
R // R ...// R (negligeable value: case for multiple parallel earths).
1 2 n
R (value normally very low, less than 1 W ).
guard wire
R = Rx + R
loop earth
By approximation, R
If this value is very high, an inspection of this earth rod is strongly recommended.
I
Rx
+ (R // R ...// R
1 2
= Rx.
loop
Guard wire
E
R earth
) + R
n guard wire
R1
32
loop
loop
R2 Rn