Huazheng HZDW-DB User manual

HZDW-DB
Ground Network Earth
Resistance Tester
User Manual
Huazheng Electric Manufacturing (Baoding) Co., Ltd

Dear use r:
Thank you for choosin g HZDW-DB g round network ear th resist an ce tester.
We hope that this instrum ent can mak e your wo rk easier an d mo re
enjoyable, so that you can get the feeling of office automat io n in the test
and ana ly si s work.
Before using the instrument, please read thi s ma nu al, and opera te an d
maintain the instrument accord ing to the manual to prolong its service life.
"Just a lig ht press, the test will be compl eted auto mati ca lly" is the
operating chara ct eristi cs of this instrument.
If you ar e sat isfied wi th th is instrument, please tell your colleagues;
if you are not satisfie d with this instrum ent, please call (03 12 ) 6775656 to
tell you to se rve you at all times-Baoding Hu azheng Electric Ma nu factur ing
Co. , Ltd., our com pa ny will definitely make you satisfied !

1
Contents
I.Use safety measures....................................................................................................................2
II.Instrument overview.................................................................................................................... 2
III.Functional features..................................................................................................................... 3
IV.Main Technical index................................................................................................................. 4
V.Instrument principle..................................................................................................................... 5
VI.Panel introduction.......................................................................................................................6
VII.Measurement wiring..................................................................................................................7
VIII.Operating steps........................................................................................................................ 8
IX. External power use................................................................................................................. 17
X.Measure ground continuity...................................................................................................... 18
XI.Measuring soil resistivity......................................................................................................... 19
XII.Measurement of ground grid resistance by angle method.............................................. 20
XIII. Packing List............................................................................................................................21

2
I.Use safety measures
1. Be sure to read this manual carefully before using this instrument.
2. Test personnel should have common sense of using general electrical equipment or
instruments.
3. The tester must strictly abide by the safety operation regulations, and must fully
understand the high-voltage test circuit and the main points of the instrument operation.
4. Non-testing personnel must stay away from the high-voltage test area. The test area
must be clearly indicated by fences or ropes, police signs, etc.
5. This instrument can only be used on power-off equipment; it must be ensured that the
ground terminals of the instrument and the equipment under test are reliably connected to
the ground network.
6. When the fuse is damaged, you must make sure to replace the fuse of the same
specification.
7. When the instrument fails, turn off the power switch and wait for one minute before
checking.
8. The instrument should avoid severe vibration.
10. The maintenance, care and adjustment of the instrument should be carried out by
professionals.
II.Instrument overview
At present, in the power system, the grounding resistance test of the earth network
mainly adopts the power frequency high current three-pole method. In order to prevent
the power frequency interference generated during the operation of the power grid and
improve the accuracy of the measurement results, the insulation preventive test
regulations stipulate that the test current of the power frequency high current method
shall not be less than 30A. As a result, many problems such as heavy test equipment,
complicated test process, high work intensity of test personnel, and long test time
appeared.

3
The gro un d network earth res istance tester adopts a new variable frequency
AC power supply, and adopts a microcomputer to control the earth network ground
resistance tester and signal processing. It solves the anti-interference problem during the
test and simplifies the test operation process. , Improve the accuracy and accuracy of the
test results, greatly reduce the labor intensity of the test personnel and test costs.
The ground netwo rk earth r esistance tester adopts a new variable frequency
AC power supply is a special instrument for measuring the grounding resistance of the
earth grid and the ground continuity between the grounding points. The instrument
adopts frequency conversion anti-interference technology, does not need high current
measurement, and can measure accurate data of 50Hz in the strong interference
environment of the substation. The measurement results are displayed by the
large-screen LCD, and the built-in micro printer can be printed out. The instrument can
measure ground impedance and ground resistance at the same time, which can more
truly reflect the actual characteristics of the ground network.
III.Functional features
1. The measured power frequency equivalence is good. The test current waveform is a
sine wave, the minimum difference between the frequency and the power frequency is
0.1 Hz, and the maximum is 10 Hz. It can be used for measurement at 50hz or 60hz.
2. Strong anti-interference ability. This instrument adopts different frequency method to
measure, and cooperates with modern software and hardware filtering technology, so
that the instrument has high anti-interference performance, and the test data is stable and
reliable.
3. High measurement accuracy. The basic error is only 0.005Ω, which can be used to
measure the earth network with very small ground impedance.
4. Powerful function. It can measure current piles, voltage piles, ground grid impedance,
ground resistance, ground continuity, soil resistivity, etc.
5. Full touch LCD screen, super large graphic operation interface, every process is very
clear. Operators can use it without additional professional training. The whole process of

4
testing can be completed with a light touch.
6. Equipped with a calendar chip and a large-capacity memory inside, the results can be
saved at any time. The history record can be viewed at any time, and can be printed out.
The current time and storage time can be displayed and printed.
7. Scientific and advanced data management: The instrument data can be exported
through U disk, and the data can be viewed and managed on any PC through special
software. Ability to generate reports and test reports
8. Safe and reliable. The instrument has functions such as grounding protection, current
limiting and voltage limiting protection, sound and light alarm to ensure the safety of test
personnel and equipment.
9. With vector test function, it can measure ground network impedance and ground
network pure resistance. The impedance angle can be measured.
10. Wiring labor is small, no need for large current wires.
11. All-in-one model, with standard resistance and constant current source, convenient
for on-site testing and reducing on-site wiring.
12. The instrument is easy to operate, and the measurement process is controlled by the
microprocessor. As long as the appropriate measurement method is selected, the data
measurement can be automatically completed under the control of the microprocessor.
13. When the user needs a large current test (such as 30A), this instrument can be
realized by an external power supply.
IV.Main Technical index
1. Measuring range: 0～5000Ω (including current pile impedance)
2. Resolution: 0.001mΩ
3. Measurement error: ±(reading×2%+0.005Ω)
4. Anti-power frequency 50Hz voltage interference capability: 10V
5. Test current waveform: sine wave
6. Test current frequency: Single frequency: 40-70Hz, resolution 0.1Hz, free setting
Dual frequency: 50±0.1Hz to 50±10.0Hz can be set at will

5
60±0.1Hz to 60±10.0Hz can be set freely
7. Output current: 5A or external power supply 30A
8. Output voltage: 400V or external power supply 1000V
9. Measuring line requirements: Current line copper core cross-sectional area ≥1.5mm2
Voltage line copper core cross-sectional area ≥1.0mm2
10. Test power supply: Built-in 2kW variable frequency power supply or external
high-power variable frequency power supply.
11. Power supply: AC220V±10%, 50Hz
12. Dimensions: 500mm*377mm*330mm, instrument weight: 20kg
V.Instrument principle
Figure 1 Schematic diagram of measurement principle
1. R0 loop resistance is about 5～200Ω
2. Rx test resistance is about 0～200Ω
3. Rf standard resistance
4. Measuring current line D: The length is 3 to 5 times the diagonal length of the ground
grid; wire diameter: ≥1.5mm2
5. Measuring voltage line 1: length is 0.618D; line diameter: ≥1.0mm2
6. Measuring voltage line 2: connect to the measured ground network
7. Measuring ground wire: grounding net
测试电源输出
微机信号处理
输出
控制
R0
Rx
Rf

6
VI.Panel introduction
Figure 2 Panel diagram
1: Current pole (C1) 2: Voltage pole (P1) 3: Voltage pole (P2)
4: Grounding grid (C2) 5: Current pole (C11) 6: Voltage pole (P11)
7: Voltage pole (P22) 8: Grounding grid (C22)
9: External AC power supply 10: External AC power supply
11: Grounding pole 12: 220V power socket 13: Power switch
14: Emergency stop button 15: LCD screen 16: 232 serial port
17: U disk socket 18: Printer
Note: Terminals 5, 6, 7, 8, 9, and 10 are only used when an external power supply is
connected.
When using the internal power supply, just leave it open.

7
VII.Measurement wiring
Figure 3 Three-pole method measurement wiring diagram
1. Measuring current wire D: wire diameter ≥ 1.5mm2, length is 3 to 5 times the diagonal
length of the ground net;
2. Measuring voltage wire 1: current wire with wire diameter ≥ 1.0 mm2 and length 0.618
times;
3. Measuring voltage line 2: Connect to a down-lead of the measured ground network.
4. Measure the ground wire: connect to a down wire of the measured ground network.
Figure 4 Wiring diagram for four-pole measurement
5. When measuring with four-pole method, draw out two connecting wires from the
ground stakes of the ground grid and connect them to the voltage pole P2 and ground

8
grid C2 of the instrument respectively, and then perform the test according to the
measurement procedure.
VIII.Operating steps
7.1. Preparation before operation
1. First check whether the current line, voltage line and ground network line used for the
test are disconnected (can be measured with a multimeter), whether the rust on the
ground pile is cleaned, and whether the buried depth is appropriate (>0.5m), and check at
the same time Check whether the connection between the test line and the ground stake
is connected. If it is not connected, please reconnect after handling.
2. The length ratio of the current test line to the voltage test line is 1:0.618, and the length
of the current test line should be 3 to 5 times the diagonal of the ground network.
3. The current test line and the voltage test line are discharged in parallel after connecting
one end to the instrument according to the specified length. The other end is connected
to two ground piles (as shown in Figure 3 or Figure 4).
4. Check the placed test line again, connect one end of the multimeter to the current line
or voltage line, and the other end of the grounding network line if there is no resistance
value displayed, it is open, confirm that it is intact and test again.
5. After checking that the connection is correct, connect the AC 220V/50Hz power supply
to the instrument and power on the instrument.
6. Press the measurement key to start measurement.
7. After the instrument displays the test, record the test data (the instrument can repeat
the measurement multiple times).
8. After turning off the power of the instrument, disconnect the connection and the test
process ends.
7.2. Operation instructions:
1. Turn on the power switch and the computer will perform self-test. After a few seconds,
the LCD screen displays the main menu in Chinese as shown in Figure 5, indicating that
the self-test is successful.

9
Figure 5 Boot interface
2. Test parameter selection explanation
1) Test frequency: 50.0±5.0Hz means using 45/55Hz double frequency conversion test.
Generally choose 50±5Hz or 60±5Hz in field test. Of course, you can choose something
else. If you want a single frequency such as 50Hz test, you can choose 50.0±0.0Hz. Here
the frequency value is set freely in the range of 40-70HZ.
2) Test mode: ground network test. Here is the drop-down menu (refer to Figure 6)
Can choose grounding test grounding resistance

10
Figure 6 Test mode selection
3) Internal power supply: here is a drop-down menu, you can choose internal power
supply or external power supply. (Picture 7)
Figure 7 Internal and external power supply selection
4) Test current: 2.0A represents the value of the test current. The current value here can
be set arbitrarily, such as 2.2A. Press the select button to select the current value.
(Picture 8)
Figure 8

11
Test current selection (normally only to 5A, 20A needs to be customized)
5) Grounding resistance wire length: the wire length when testing grounding resistance,
generally choose 20 meters.
6) Design short-circuit current: The current when a single-phase short-circuit occurs
during the design of the substation. Generally 1kA.
7) Under the boot interface (Figure 5), the red numbers are modified. For items such as
test frequency, you only need to use a touch screen pen or finger to click, and the
numeric keyboard will pop up and then modify. (Picture 9)
Figure 9 Red digital parameter modification interface
After filling in the numbers, press the OK key, the keyboard disappears, and the input
data is reflected in the input box.
After filling in the numbers and pressing the esc key, the keyboard disappears and
the entered data is invalid.
7.3. Ground network resistance test
In the boot interface (Figure 5), select the test mode for ground network test, and use a
touch screen pen or finger to click
Start the instrument test, and the test confirmation interface appears (Figure 10):

12
Figure 10 Test confirmation interface
Click OK to start the up-current test. Please confirm that the test line has been connected.
At this time, the ground network test interface will appear (Figure 11). Click Cancel, and
the instrument will return to the startup interface (Figure 5).
Figure 11 Ground network test interface
I=2.000A Instantaneous current during the test.
U=0.151V Instantaneous voltage during test.
R=0.075Ω instantaneous impedance during testing. F=55.00Hz constant current source
frequency (double frequency conversion F1)
F=45.00Hz constant current source frequency (double frequency conversion F2)
Progress: 84% means 84% of the test is completed, etc.
To 100% test is completed.
After the test is completed, the ground network test result interface appears (Figure 12)

13
Figure 12 Ground network test result interface
The meaning of the measurement results is as follows:
Zx = 75.777mΩ: ground network impedance value
Rx = 75.770mΩ: pure resistance of the ground grid
Φ = 0.769°: vector angle value
X = 0.001Ω: ground network inductance value
L = 0.003mH: ground grid inductance value
Press exit at this time to return to the boot interface (Figure 5). Press print to print out the
result.
Press the store button. The data storage interface appears (Figure 13).
1. Click the data box, a small
Keyboard, fill in the storage serial number.
2. Press the store button, data
After storing, it will return automatically.
3. Press the cancel button to return without saving.

14
Data storage interface (Figure 13)
7.4 Ground resistance test
In the boot interface (Figure 5), select the ground resistance test mode, (the line length is
generally 20 meters) use the touch screen pen or finger to click to start the instrument
test, the test confirmation interface appears (Figure 14):
Figure 14 Test confirmation interface
Click OK to start the up-current test. Please confirm that the test wire has been connected.
At this time, the grounding resistance test interface will appear (Figure 15). Click Cancel,
and the instrument will return to the startup interface (Figure 5).

15
I=2.002A instantaneous current during testing.
U=0.153V The instantaneous voltage during the test.
R=0.076Ω instantaneous impedance during testing. F=55.00Hz constant current source
frequency (double frequency conversion F1)
F=45.00Hz constant current source frequency (double frequency conversion F2)
Progress: 84% means 84% of the test is completed, etc.
To 100% test is completed.
Figure 15 Ground resistance test interface
After the test is completed, the ground resistance test result interface appears (Figure 16)

16
Figure 16 Ground resistance test result interface
The meaning of the measurement results is as follows:
R = 76.138mΩ: Grounding resistance value
ρ=9.567Ω.m: soil resistivity value
I=2.000A: Test current value
U=0.152V: ground voltage value
Press exit at this time to return to the boot interface (Figure 5). Press print to print out the
result.
Press the store button. The data storage interface appears (Figure 17).
Data storage interface (Figure 17)
1. Click the data box, a small
Keyboard, fill in the storage serial number.
2. Press the store button, data
After storing, it will return automatically.
3. Press the cancel button to return without storing.
7.5 Instructions for self-diagnosis of the instrument during the test
1) When [Please power on and restart], the internal power supply of the instrument may
be protected, shut down and restart.

17
2) [Power module error, please contact the manufacturer], if the test continues, please
contact the manufacturer.
3) When the test current is 0.0A, the connection of the [current line] may be in poor
contact with the [current pole] ground pile or there are too few ground piles. It is
necessary to add ground piles to reduce loop resistance. The pile depth is not less than
0.5m. The resistance of the current pile should be less than 80Ω.
4) If the measured value displayed by the instrument is extremely low (<0.01Ω), it may be
that the voltage line is not connected.
5) When the instrument is tested, a resistor of more than 20 ohms can be connected in
series to the C1 output terminal to simulate the field current pile resistance.
6) To make the test go on smoothly, please use a multimeter to check whether the
contact point between the test lead and the ground pile is intact, and measure whether
the laid line is open.
7) The instrument will automatically eliminate wiring errors during the four-pole
measurement.
8) If there are other malfunctions in the instrument, please contact the after-sales service
department of our company directly, and do not disassemble the machine privately.
4. The measuring line is configured by the user according to the size of the ground
network.
IX. External power use

18
1. When using an external power supply, you only need to wire it as shown above.
2. Turn on the machine and select the external power supply on the initial interface.
3. Set the frequency so that the frequency is equal to the frequency of the external power
supply.
4. Click the test external power button, and the screen displays the size of the external
current. Adjust the external variable frequency power supply according to the size of this
current to make the current meet the requirements of the test. Return to the initial
interface.
5. Click the Start Instrument Test button to start the test.
6. All test methods of external power supply are exactly the same as internal power
supply test. I will not repeat them here.
X.Measure ground continuity
C1/P1 is connected to a grounding device, C2/P2 (measurement grounding terminal) is
connected to another grounding device.
note:
1. Do not coil the lead wire.
2. Keep voltage wires away from current wires as much as possible.
3. Both sides of the grounding clamp should be pressed tightly to prevent poor contact
caused by paint corrosion.
4. To prevent current protection, select a current of 2A.
Select ground grid frequency conversion 2A