HVTest HT2571B User manual

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Dear Client
Thank you for Purchasing our HT2571B Earth Resistance
Tester. Please read the manual in detail prior to first use, which will
help you use the equipment skillfully.
Our aim is to improve and perfect the
company's products continually, so there may be
slight differences between your purchase equipment
and its instruction manual. You can find the changes
in the appendix. Sorry for the inconvenience. If you have further
questions, welcome to contact with our service department.
The input/output terminals and the test column
may bring voltage, when you plug/draw the test wire or
power outlet, they will cause electric spark. PLEASE
CAUTION RISK OF ELECTRICAL SHOCK!
Company Address:
T4，No. 41, High-tech 2 Road，East Lake High-tech Development Zone，
Wuhan
Sales Hotline: [phone]
After Service Hotline:[phone]
Fax: [phone]
E-mail: [email protected]
Website: www.hvtest.cc

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SERIOUS COMMITMENT
All products of our company carry one year limited warranty
from the date of shipment. If any such product proves defective
during this warranty period we will maintain it for free. Meanwhile
we implement lifetime service. Except otherwise agreed by
contract.
SAFETY REQUIREMENTS
Please read the following safety precautions carefully to avoid
body injury and prevent the product or other relevant subassembly
to damage. In order to avoid possible danger, this product can only
be used within the prescribed scope.
Only qualified technician can carry out maintenance or repair
work.
--To avoid fire and personal injury:
Use Proper Power Cord
Only use the power wire supplied by the product or meet the
specification of this produce.
Connect and Disconnect Correctly
When the test wire is connected to the live terminal, please do
not connect or disconnect the test wire.
Grounding
The product is grounded through the power wire; besides, the

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ground pole of the shell must be grounded. To prevent electric
shock, the grounding conductor must be connected to the ground.
Make sure the product has been grounded correctly before
connecting with the input/output port.
Pay Attention to the Ratings of All Terminals
To prevent the fire hazard or electric shock, please be care of
all ratings and labels/marks of this product. Before connecting,
please read the instruction manual to acquire information about the
ratings.
Do Not Operate without Covers
Do not operate this product when covers or panels removed.
Use Proper Fuse
Only use the fuse with type and rating specified for the product.
Avoid Touching Bare Circuit and Charged Metal
Do not touch the bare connection points and parts of energized
equipment.
Do Not Operate with Suspicious Failures
If you encounter operating failure, do not continue. Please
contact with our maintenance staff.
Do Not Operate in Wet/Damp Conditions.
Do Not Operate in Explosive Atmospheres.
Ensure Product Surfaces Clean and Dry.

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－Security Terms
Warning: indicates that death or severe personal injury may
result if proper precautions are not taken
Caution: indicates that property damage may result if proper
precautions are not taken.

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Contents
I. Introduction··························································· 6
II. Technical Specifications·········································· 8
III. Operation Instructions·············································9
IV. Notes··································································· 11
V. Packing list···························································13

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I. Introduction
1. Working Principle
The instrument is a newly developed earth resistance tester,
which abandons the traditional way of generating electricity by
hand operation, uses advanced middle-large scale integrated
circuits and applies DC/AC transformation technology to
combine three-terminal measurement method and four-terminal
measurement method into one model.
The working principle is that: the built-in DC/AC converter
transform DC current into AC low-frequency constant current
through the auxiliary grounding electrode C and the circuit
composited by the measured object E.Then on measured
object generate AC voltage drop that will be sent to AC amplifier
via the auxiliary grounding electrode P and be enlarged, and
then display on the table through the detector. With
magnification switch, three different range limits are available:
0 ~ 20Ω, 0 ~ 200Ω, 0 ~ 2000Ω.
2. Application
The instrument applies to power industry, post and
telecommunications, railway, communications, mining and
other sectors to measure the grounding resistance of the
various devices and the conductor resistance of low resistance;

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this instrument can also measure soil resistivity and ground
voltage.
3. Main features
1) High-strength aluminum alloy shell body, the circuit
equipped with phase locked loop and switched capacitor filter,
based on which the instrument play an effective role in shielding
power frequency and radio frequency interference.
2) DC/AC converter can transform DC current into AC
low-frequency constant current for the measurement.
3) Auxiliary grounding resistance can change in the
range of 0 ~ 2KΩ (RC), 0 ~ 40KΩ (RP), that will not affect
measurement results.
4) Without manual adjustment to zero, with three and a
half bits LED display, the instrument can be used for
measuring the grounding resistance, the conductor resistance
of low resistance, soil resistivity and AC ground voltage.
5) If tested loop encounter failure, the screen displays
"1" indicating large range, which consistent with conventional
measurement practices.

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II. Technical Specifications
1. Operating Conditions
Temperature: 0 ℃~ +45 ℃
Relative humidity: ≤ 85%
2. Measuring range and constant current value (virtual
value)
Resistance:
0 ~ 20Ω (10mA), 2 ~ 200Ω (1mA), 20 ~ 2000Ω (0.1mA)
Voltage: AC 0 ~ 19.99V
3. Measurement accuracy and resolution
Accuracy: 0 ~ 0.2Ω ≤ ± 3% ± 1d
0.2Ω～1999.9Ω≤±1.5%±1d
1～19.99V≤±3%±1d
Resolution: 0.01Ω, 0.1Ω, 1Ω, 0.01V
4.Measurement errors caused by auxiliary grounding
resistance and ground voltage
Auxiliary grounding resistance RC (between C1 and C2)
0 ~20Ω ≤ 1KΩ
20 ~ 2000Ω ≤ 2KΩ
RP (between P1 and P2) <40KΩ error ≤ ± 5%
Ground voltage (frequency virtual value) ≤ 5V error ≤ ± 5%
5. Power supply and power dissipation

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Maximum power dissipation≤ 2W
DC: 8 × 1.5V (AA, R6) Battery
AC: 220V/50Hz
6. Dimensions and weight
Dimensions: 220× 200 × 105mm
Weight: ≤ 1.4kg
III. Operation Instructions
1. Grounding resistance measurement (Fig. 1)
As Fig.1, the straight-line distance between ground
electrode E (C2, P2) and current probe C1is 40 meters. Put
potential probe P1 on the center of E, C, so that E, P, C is 20
meters away from each other and make sure potential probe P1
grounded properly.
Connect ground resistance terminals E (C2, P2), P1, C1 to

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their corresponding probes with special wire.
Turn on the power switch; select the appropriate gear and
press the “confirm” key, at selected gear the indicator lights,
data display on LCD is the measured ground resistance.
2. Soil resistivity measurement (Fig. 2)
1) As Fig. 2: when measuring, insert four probes into the
measured soil along a straight line, make sure the insertion
depth is 20cm and spacing of each probes is 20cm. connect
terminals C1, P1 , P2, C2 to the four probes with wire. If the
measured resistance value is R, the soil resistivity can be
calculated as follow:
Ф = 2πRL
Among
Ф-soil resistivity (Ω • cm)
L-spacing of each probes (cm)
R-the readings of grounding resistance (Ω)
The measured soil resistivity by this method is
approximately equal the average soil resistivity in the region

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where probes were inserted.
2) The probe used for measuring grounding resistance
and soil resistivity is aluminum tube or round steel. Generally its
diameter is 25mm and its length is 0.5 ~ 1m.
3. Conductor resistance measurement (Fig. 3)
4. Ground voltage measurement
Wiring as Fig. 1, pull out the plug C1, insert the plug
between E, P1, and start the ground voltage gear (EV), the
indicator lights. The reading on LCD is AC ground voltage value
between E, P1.
5. Completed measurement, turnoff power supply, the
instrument shut down.
IV. Notes
1. When the instrument is stored you should pay attention to
environment temperature and moisture. It should be placed in
dry and ventilated environment and should be shielded from
humidity, acid, soda and corrosive gas damage.

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2. When measuring and protecting grounding resistance,
you must disconnect power supply. For grounding resistance is
less than 1Ω, you should separately connect it to the grounding
object with special lead, C2 on the outside, P2 in the medial.
Shown in Fig. 4:
3. When measuring grounding resistance of large grounding
grid, the wiring method is different from the general method,
detailed wiring please refer the measurement requirement of
current meter or voltmeter.
4. When measuring grounding resistance, you’d better
measure in different directions for 3 to 4 times and take the
average.
5. The instrument uses AC and DC power supply. When
connect to AC power supply, the instrument will prior use AC
power supply; when not connect to AC power supply, battery
will power tester.

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6. “←” appearing on the top left corner of the screen
says battery voltage is low and you should replace a new
battery. If the instrument will not be used for a long time,
all batteries should be removed to prevent the instrument
from corrosion.
V. Packing list
No.
Name
Qty.
1
Instrument host
1
2
Test wire （1.5m）
2
3
bobbin bracket
（20m black wire，40m red wire）
1
4
Ground Probe
2
5
Battery
8
6
AC 220V Power Cord
1
7
The instruction manual
1
8
Inspection report
1
9
Certificate
1

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