MI 3290 Earth Analyser
Appendix F - The balancing procedure
160
2. Balancing procedure
Balancing procedure is the sub-procedure of the Selective Flex method where positions S
B1
and
S
B2
are defined.
The balancing procedure is used only if the Selective (Flex clamp 1-4) measurement method in
combination with the in-line probe set-up is used.
Before starting the balancing procedure, the flex clamp(s) has (have) to be positioned on the
tested object and connected to instrument and the Distance (R) value for the distance between
E and H has to be entered.
These balanced positions are calculated by MI 3290 if the balancing procedure is started by
selecting the
button in the control panel of the Selective (Flex clamps 1-4) measurement:
Balancing procedure is enabled only if single Test Mode is selected.
After the balancing procedure returns the r
1
and r
2
values, the user has to decide, which position
he will use for the measurement, the S probe has to be positioned to the selected balanced
position and then the actual measurement with the flex clamps can be started.
Note:
If the Selective Flex method is used in combination with mirror or triangle probe set-up, the
Selective (Flex clamp 1-4) measurement is started immediately without balancing.
Note:
The balanced position depends on the distance R and the total impedance of the system and is
therefore frequency dependant. After the balancing procedure is performed neither the distance R nor the
frequency of the test current should be changed.
E a r t h
H
S
ES
E
MI 3290 Earth Analyser
G
V
A
S - probe
H - auxiliary
earth rod
F2
F1
Flex clamp
fset
tower
ne
x
to
w
er
overhead grounding wire
L
GW
ne
x
to
w
er
L
GW
Ie
If1
If2
Ih
Igw
Igw
R
r2
r1
Figure F.1: Selective (Flex Clamps 1-4) example (Balancing)
In the example below, values of r
1
and r
2
are calculated according to the above listed equations:
Example of measurement results:
I
f_1
+ I
f_2
= 44 mA, I
e
= 138 mA, R = 75 m
