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UNI-T UT521 Manual De Instrucciones página 4

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P/N:110401104451X DATE:2018.06.26 REV.4
5.2
Test leads connection
Make sure all the test leads are firmly connected to the Tester input terminals;
Poor connection will affect the measuring accuracy.
6. Making Measurements
The voltage up to 50Vac will be present between E and C input terminals
during earth ground resistance measurement. To avoid any electric shock,
do not touch exposed metal part of test leads and auxiliary earth stakes.
6.1
Precision Measurement (with use of standard test leads):
a. place 2 ground stakes deep into the soil. Earth electrode(E), probe(P) and
auxiliary earth (C) should be in a straight line and 5-10m apart from each other.
See Figure 2 for the connection.
( Caution: ensure the ground stakes in the damp soil. If the soil is too dry, it
need to fill-in sufficient water. Stony or sandy soils also needs to be dampened
before test. If the testing site is covered with concrete in the city area, which
makes it impossible to insert the ground stakes, you can place 25cm X 25 cm
two steel plates (or the existing ground stakes) horizontally on concrete
surface, and cover with the towel dampened sufficiently with water, then
measuring electrodes are produced and under general circumstances, the
measurement can begin now.)
m
m
Earthed Electrode
Auxiliary
Under Test
Earth stakes
Figure2
C: auxiliary electrode
P: potential electrode
b. Measuring Earth Voltage:
1) Set the rotary switch to EARTH VOLTAGE, LCD shows the Tester enters into
earth voltage test status.
2) Insert test leads into V and E terminals and then connect them to tested points.
(Do not make any connection to other terminals)
3) The measured earth voltage shows on LCD. If the measured voltage is >10V,
please switch off all related electrical equipments and wait until this voltage
decreases before you makes any earth resistance measurement, otherwise it
may affect the accuracy of earth resistance measurement.
Warning:
Only V and E input terminals are used for earth voltage measurement, do not
make any connection to C and P terminals. Otherwise, it will cause danger and
damage the Tester.
c. Measuring Earth Ground Resistance:
1) Set the rotary switch to earth ground resistance 2000Ωrange.
2) Press "TEST" button, the button will be illuminated, indicating the instrument is
under measurement status. And LCD shows the measured earth resistance value.
If measured earth resistance:<200Ω, turn the rotary switch to 200Ω range;
<20Ω, turn the rotary switch to 20Ω range;
Or you can select earth resistance range in an order you like, however, to obtain
accurate value, make sure you have selected the best range for your measurement.
Caution:
● If C or E input terminal is not well contacted, or auxiliary earth resistance or
measured earth ground resistance is too large or input terminal are opened
( > 14kΩ at 20Ω range), the LCD will show "- - - -Ω". Please check if the test
leads are firmly connected or the soil is too dry or the auxiliary earth stake has
been properly inserted into the earth.
● When measured earth resistance is out of range, and it is<14kΩ at 20Ω range
or <26kΩ at 200Ω range or <78kΩ at 2000Ω range, LCD will show "OL" icon
(Overloaded).
● The reading may be affected if auxiliary stakes are bent or in contact with other
objects. So please clean the earth stakes before connecting the test leads,
otherwise it may cause deviations to the readings if the auxiliary stake has a large
resistance.
d. Auto Power Off: The Tester will automatically switch off to conserve the energy
after the buttons and rotary switch keep inactive for 10 minutes (except under
earth resistance test status.)
e. Backlight: When making measurements in dimly lighted sites, press "Light
/Load" button to turn on the backlight, and its icon indicates on LCD accordingly.
Press it again to turn off the backlight.
f. Data Hold: During the measurement, gently press "Hold/Save" to freeze the
measured value, indicated by HOLD icon on LCD, press the button again to
disable the function.
g. Data Storage:
1. Save Data: Long press "Hold/Save" button for 2seconds to enable Data Save
function and meanwhile save the data accordingly, then gently press the button
again to save the second set of data, circulate so on and so forth. To cancel the
function, long press "Hold/Save" for 2s to exit.
2. View Data: Long press "Light/Load" for 2s to recall NO.01 data, then gently
press the button to recall NO.02 data.... up to 20sets of data. To return to
previous set, gently press "Hold/Save" button.(Under this status, "Hold/Save"
Warning
Red
Yellow
Green
E: earth electrode
and "Light/Load"(gently press) buttons are used as Up and Down button). To
exit the function, long press "Light/Load" button for 2s.
3. Clear Saved Data
Press and old "Hold/Save"button and "Light/Load"button simultaneously, then
switch-on the Tester, LCD display will show"C L .",
Meanwhile, all the data in the memory will be deleted no matter whether the
memory is full or not.
6.2 Simple Measurement (with use of simple test leads):
This method is applied when auxiliary stake is impossible to use, which use an
exposed object with low earth resistance as one electrode, such as metal water
slot, pipe, common earth of power supply wiring, earth ground terminal of buildings,
etc.(using E and P&C terminals).See Figure 3 for wire connection:
Supply Transformer
Primary
Secondary
Side
Side
r
Reference Earthed
Earthed Electrode
Electrode
Under Test
Figure 3
When using this method, P and C have already been connected together.
Danger
Please take extreme caution about the electric shock when using earth
ground terminal of commercial power system as a reference test point.
7. Maintenance & Repair
7.1
Maintenance
7.1.1 Replacing the Battery (See Figure 4)
Please replace the battery timely when low battery indicator shows. Follow
the steps as below:
a. switch-off the Tester and remove all the test leads.
b. release the screw in bottom part,and open battery compartment.
c. Replacing all old battery (6) with new battery.
d. After replacing the battery, rejoin the battery compartment and firmly screw.
Remove all the batteries if the Tester do not use for a long time so as to
avoid the leakage and corrosion in the battery compartment.
7.1.2 Cleaning the Tester
Soft cloth and mild detergent should be used to clean the surface of the Tester,
no solvent or alcoholic is allowed for it may damage the display.
7.1.3 Must be avoiding moisture.
7.2
Repair
7.2.1 Contact our after-sales service department or agents when the following
incidents happen:
a. The Tester is being damage.
b. LCD display abnormally.
c. Unreasonable deviation when in normal use.
d. Buttons do not function properly.
7.2.2 when the Tester needs repair, please have it serviced by qualified
professional personnel or authorized service center.
**END**
This operating manual is subject to change without notice.
Red
Green
Figure 4
2

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