HVTest HTZZ-2A User manual

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Dear Client
Thank you for Purchasing our HTZZ-2A Transformer DC
Winding 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
ground pole of the shell must be grounded. To prevent electric

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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. Overview................................................................................................. 6
II. Application............................................................................................. 7
III. Performance characteristics..............................................................7
IV. Specifications.......................................................................................8
V. Panel Layout....................................................................................... 10
VI. Working Principle.............................................................................. 10
VII. Operation Methods..........................................................................11
VIII. Problems and Solutions................................................................ 14
IX. Notes................................................................................................... 14

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I. Overview
DC resistance measurement of transformer winding is an
essential test project during transformer transfer, repair and
changing tapping switch. Measuring DC resistance of transformer
winding, you can check out weld or connection quality of down-lead,
the winding inter-turn short circuit or open circuit, and whether
tap-changer is well contacted. In the previous it is generally to use
QJ44 double bridge to measure DC resistance, but the measuring
current for this type of bridge is mA level current. So measurement
will take a long time, and accuracy is lower. In order to change the
above situation, our company has developed this product.
This instrument is a high-precision regeneration product used
to replace DC single/double bridge. Equipped with advanced switch
power supply technology, the measurement speed of the
instrument is faster a hundred times than that of the bridge. Using
four and half bits LCD to display the measurement results and
three and half bits LCD to display ambient temperature or test
current value, it overcomes the shortcoming of other similar
products that it is difficult to read value from the LED display in the
sun and possesses automatic arc suppression function. The
instrument is characterized by fast test speed, high precision,
intuitive display, strong anti-interference ability, small size, low

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power consumption, stable and reliable test data. Built-in
rechargeable battery pack (14.8V) and AC/DC dual-use, the
instrument is very convenient for on-site and field test.
The instrument meets DLT 845.3-2004 "resistance
measurement device general technical requirements- Part 3 DC
Resistance Tester" requirements.
II. Application
The instrument is an ideal device to measure different
inductive load DC resistance and of low-voltage switch contact
resistance, wire and cable resistance, welded joint resistance of
power transformers, large motors and instrument transformers.
III. Performance characteristics
1. Fast test: The maximum output charge current of the
instrument is up to 2A. When measuring it can effectively
compensate current inertial for large inductor and accelerate core
saturation, thereby reduced the charging time and increased test
speed. Its test speed is faster hundreds of times than the traditional
single instrument and double bridge.
2. High accuracy: The application of advanced four-terminal
measurement and constant current source technology to the
instrument makes the inductive load charging current hold a

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relatively stable value. Base on that, and the instrument with stable
anti-sense capability and strong anti-interference characteristics
can ensure the accuracy of measurement. And the use of imported
high-quality components not only improves the measurement
accuracy, but also makes the instrument have good repeatability.
3. Wide measurement range: resistance measurement range
1μΩ ~ 20KΩ, wide range.
4. AC and DC power supply: Attached rechargeable battery,
the instrument can use AC and DC power supply. Portable design,
it is easy to carry and use.
IV. Specifications
1. Work Environment:
Temperature: 0℃～40℃
Relative Humidity: ≤85 %RH
2. Measurement Range:
The instrument has seven ranges as follows:
1μΩ～20mΩ;
20mΩ～200mΩ;
0.2Ω～2Ω;
2Ω～20Ω;
20Ω～200Ω;
200Ω～2kΩ

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2kΩ～20kΩ
3. Measurement Accuracy：±(0.2%+2d)
4. Maximum Resolution: 1μΩ
5. Constant current source:
2A (1μΩ～20mΩ, 20 mΩ～200mΩ, 0.2Ω～2Ω);
200mA (2Ω～20Ω);
10mA (20Ω～200Ω);
1mA (200Ω～2kΩ)
100uA（2kΩ～20kΩ）
6. Working Voltage:
DC: 12V～16.8V
AC: 220V
7. Power Dissipation: ≤15W
8. Dimension: 365×330×180mm3
9. Weight：5kg (included test clamp and test lead)

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V. Panel Layout
Picture 1 panel layout
1. resistance range select
2. resistance
3. Tem/current
4 .Tem sensor
5.Tem/current select
6. test line jack
7 .working status
8 .start/stop
9 .power switch
10 .power indicator
11. 220V plug
12. ground
VI. Working Principle
There is a constant current source in the instrument that can
supply DC current. When measuring resistance, constant current
be fed into the tested object from terminals I +, I-, then which will
yield voltage in the tested object, the value of that voltage retake to

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the instrument at terminals V +, V, after amplification, the display
will show the resistance value using four and a half bits LCD digital.
VII. Operation Methods
1. Power supply
This instrument provides two power sources for test:
AC220V/DC14.8V. In the case of strong electromagnetic
interference, the best choice is use the DC power supply for test. At
this state the instrument can get stable tested value with strong
anti-frequency interference ability.
1) DC power supply test:
Closed power switch, power indicator will light. Press
“start/stop” buttons, then select appropriate resistance gear switch
to do the test. Finished testing, press “start/stop” button,
"discharge" indicator lights (if the stored electricity of tested object
is little, the "discharge" indicator does not light), after discharge,
"discharge" indicator goes out, and then convert the test clip for
re-test.
2) AC power supply test:
Connect to AC 220V power supply, its indicator lights
("charging" indicator or "full" indicator); closed the power switch,
power indicator lights, and press the "start/stop" button, then select
appropriate resistance gear switch to do the test. Finished testing,

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press “start/stop” button, "discharge" indicator lights (if the stored
electricity of tested object is little, the "discharge" indicator does not
light), after discharge, "discharge" indicator goes out, and then
convert the test clip for re-test.
3) Charge
Connect to AC220V power supply, "charging" indicator lights
indicating the rechargeable battery is charging. If rechargeable
battery’s power is sufficient, "full" indicator will light. When using AC
power to test, the instrument also can charge up the battery.
(Instrument equipped with charging protection circuit will not
produce overcharging phenomenon.)
2. Test line connection method
Well connect terminal I +, V +, V-, I- to the tested target as the
wiring method in picture 2. The connection method can eliminate
the effect of contact resistance and line resistance on the
measurements.
Picture 2 wiring
Instrument Host
Tested
target RX

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In measuring, if the length of test line is not enough, you can
use lead having same size diameter to extend it.
3. Measurement
Well connected the test line as fig. 2, closed power switch,
power indicator lights, and press the "start/stop" button, then the
display shows "E0000". According to the measured value select
appropriate resistance gear range, press its switch, then its
indicator lights, the four and half bits digital stably shown in LCD is
the measured resistance value. When reading resistance value,
please pay attention to the unit of selected range (mΩ / Ω / kΩ).
Measuring large inductance such as power transformer, you’d
better keep the coils not measured short-circuited to avoid
electromagnetic interference.
4. Discharge
Finished measurement, you can directly disconnect main
power. For measuring inductive object, it is not recommended
immediately disconnect the wiring after disconnected the power,
the instrument should be left to continue discharge. General
discharge time is at least 20 seconds; otherwise the EMF of the
inductance could endanger personal safety.

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VIII. Problems and Solutions
Problems
Solutions
Display resistance
value “E0000”
Did not choose resistance range.
Wiring error.
Tested resistance value exceeds rang, please connect to large range.
The screen do not
display resistance
value
Did not press “Start/Stop” key.
IX. Notes
1. After testing, please charge the battery in time.
2. During DC test, if the undervoltage indicator light became
bright, please use AC power instead of DC power for test.
3. If the instrument will not be used in long-term, please charge
up the battery regularly (two months) until the "full" indicator lights
up, generally charge time is about 6 hours.
4. You should prevent the instrument damp, falling, and
exposure.