Sonel MRU-30, Руководство пользователя, Страница: 31 / 56

MRU-30
– USER MANUAL
29
To delete the AUTO-ZERO correction and restore default calibration repeat the
above steps with open (not shorted) test leads. An
oFF message will appear and
test lead compensation is now de-activated. When the procedure completes the
AUTO-ZERO message will disappear from the screen.
or After 20 seconds the meter returns to the standby
screen where a measurement can be started.
Press
ESC or ENTER to skip, and return to the
standby screen immediately.
4.10 Earth resistivity measurement
(ρ)
The earth resistivity measurement mode is used to gather resistivity data for the design of a
protective ground earthing system project, as well as for geology studies. The measurement method is
identical to the four-pole earth ground resistance measurement, but includes the distance between the
electrodes. The result is the resistance value calculated in accordance with the following formula:
ρ = 2

LR
E
, (
Wenner’s measurement method). The method assumes equal distances between elec-
trodes.
Use
<<
or
>>
buttons to select the earth
resistivity measurement mode: The LED
is illuminated. The meter is now in the
state of measuring interfering noise voltage
between the measurement terminals, as
well as measuring current with the receiving
clamp.
Press SET/SEL button to switch into mode
of selecting the distance between the auxil-
iary electrodes.
Use the and
buttons to set the dis-
tance between the auxiliary electrodes.
From 1 to 50 m, in 1 m steps, or from 1 to
150 ft, in 1 ft steps.
Use the
button to select the test volt-
age.
Use the
and
buttons to select the
measurement voltage value of 25 V or 50 V.
or Press
ENTER
to save the setting or
press ESC to exit without saving.