
UT521 USERS MANUAL
1
Content
Chapter Page
2
5
6
9
10
11
18
1. Safety Instructions
2. Characteristics
3. General Specifications
4. Product outlook & accessories
5. Preparation before measurement
6. Measurement Operation
7. Maintenance & Repair

UT521 USERS MANUAL
2
1.Safety Instructions
This operation manual includes the user guidance and safety instruction when using
the tester, please read it before using.
Before using the Tester, please read and understand the operating manual
including the content.
Keep the operating manual properly, and let it easy to get it for reference during
the process of testing.
When using the Tester, user must follow the testing procedure as mentioned in
the operating manual.
Careful reading the operating manual regarding the safety information and it is
content.
Must be followed all the related safety instructions, otherwise it may cause
accidents or damage the Tester.

UT521 USERS MANUAL
3
Danger identifies conditions and actions that most likely pose hazard(s)
or die.
Warning identifies conditions and actions that will pose hazard(s) or
die.
Caution identifies conditions and actions that will pose hazard(s) or
damage the Tester.
Safety sign " "has 3 meaning in this manual, user has to pay attention to this
sign" "for operation.
Danger
Do not use the Tester around explosive environment, which may cause fire and
explosion.
Do not use the Tester in wet environment or do not make any connection work
when your fingers are wet.
Do not apply the load more than the Tester capacity or range.
Do not open battery compartment while testing.

UT521 USERS MANUAL
4
Warning
Do not use the Tester if it is damaged or metal part is exposed.
Do not disassemble the tester un-intentionally. If it needs repair, please contact
our after-sales services or our agents.
Do not change battery or open battery compartment when the Tester is wet. Soft
cloth should be used to dry it first, and then carry on.
Make sure the Tester is turned off when changing battery or opening the battery
compartment.
Caution
Ensure test lead probe insert into the corresponding port before measurement.
Take the battery out from the Tester if it is not used for a long time.
Do not expose the Tester in extreme temperature and wet environment.
Soft cloth and mild detergent should be used to clean the surface of the Tester
when servicing. No abrasive and solvent should be used
Dry the tester before storing if it is wet.
This Tester has the follow signs,please pay attention to the content when using:
identifies danger, warning, caution identifies double or reinforced insulation
identifies AC[AC] Grounding
Conforms to Standards of European Union

UT521 USERS MANUAL
5
2.Characteristics
The Tester is using micro controller with high accuracy and reliability; it can measure
every electric wire, electric installation, anti-thunder equipmentÃs earth resistance
value of those earth system. Also, it can carry earth voltage measurement. (Note:
the Tester should not be used outdoor hazard environment, like raining, thunder
etc.)
2.1 With backlight display and battery check function.
2.2 Data logging for 20 sets of data.
2.3 With auto switch-off save energy function.
2.4 Precision 3-Wires Testing and Simple 2-Wires Testing.
2.5 During earth voltage testing, if C port or E port don't contact properly , LCD display
will show"- - - - "indication.
2.6 Over-range Display"OL"indication.
2.7 Double insulation or reinforced insulation safety manufacturing.

UT521 USERS MANUAL
6
3.General Specifications
3.1 Operating temperature and Relative humidity(20 5 & 75%RH):
3.2 Application standard:
IEC 61010-1 CATIII 600V Polluting Grading: Grade II
IEC 61557-1,5
IEC 61010-2-31
Range
Earth Voltage
Measure Range
0V~200V(50/60Hz)
Earth
Resistance
Best Accuracy
(1.0%+4)
(2.0%+10) (20 position)
(2.0%+3)(200 or 2000 position)
(Auxiliary earth resistance 500
(accuracy 5%);earth voltage 10Vac)
0.00 ~20.00
0.0 ~200.0
0 ~2000
20
200
2000

UT521 USERS MANUAL
7
3.3 Measure methods:
(1) Earth Voltage Testing:average respond
(2) Earth Resistance Testing : testing signal frequency : around 820Hz,current :
20 position around 3.2mA
3.4 Maximum operating accuracy:
Maximum operating accuracy within measure range:( 30%)
20 : 5.00 ~20.00
200 : 20.0 ~200.0
2000 : 200 ~2000
3.5 Working condition:
Temperature:5 ~40
Relative humidity: 80%RH(no fog)
Height above Sea Level: 2000 meters
3.6 Storage condition:
Temperature:-20 ~60
Relative humidity: 75%RH(no fog)