HVTest HT-TC User manual

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Dear Client
Thank you for Purchasing our HT-TC Cable Fault Locator.
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. Product introduction........................................................................... 6
Ⅱ. Product features and technique parameters................................. 7
Ⅲ. Low Voltage Impulse Testing Method.............................................9
IV. High Voltage DC Flashover Method............................................. 11
V. High Voltage Impulse Flashover Method...................................... 12
VI. Fundamantal Principle and Composition..................................... 13
VII. Panel Controlling and Keymanual’s Function............................ 15
VIII. Instrument use fault test method................................................. 16
IX. Announcement..................................................................................22
X. Packing list..........................................................................................24
XI.Common fault repair..........................................................................24
Appendix.................................................................................................. 25

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Ⅰ. Product introduction
The normal operation of cable-communication and electric
transport completely rely on the good condition of the
cable-circuit. Once the circuit breaks down and without
punctually examination and repairing, it will no doubt trigger the
mass economic loss and bad social influence. So the electric
fault measuring testing instrument is a very important tool. The
intellectual testing instrument uses multiple testing methods
and adopts the most advanced electronic devices and with
computer and special electronic technology, combining our
company’s successful experience of long-time exploitation on
cable-fault measuring testing instruments, and it is absolutely of
high tech, intelligence and abundant functions.
Our cable-fault detector is a testing device of good integrity. It
can test on the High Resistance Flashover Fault, Grounding
High and Low Resistance Fault, Short & Off Circuit on the
Cable Fault and Poor contact and etc. If being equipped with
sounding method and locating instrument, it can exactly detect
the fault point. Furthermore, it especially applies to test for
various power cable and communication cable.

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Ⅱ. Product features and technique parameters
1. Functions
1.1 Multiple functions
Safe, quick and accurate test. The instrument applies the methods
of Low Voltage Pulse and HV Flashover. It can test all kinds of
faults, especially on the Flashover and High Resistance fault
testing and without burning through. If it is equipped with locating
instrument, it can exactly point out the location of the fault.
1.2 High Precision
Our instrument uses the tech of high speed data sampling, the
speed of A/D is 100MHz, and makes resolution ratio of 1m and
testing dead zone of 1m.
1.3 High intelligent
The testing results automatically show by wave form and data on
the large LED. It is easy for viewing. It does not need especial
training for operators.
1.4 Function of Wave Form and Parameter Saving & Reading
It uses non-volatile devices and after turning off, it still saves the
wave form and data.
1.5 Function of Double-trace Showing
It can compare the wave forms of fault-manner cables and those of
the regular ones. It is benefit for the further testing of the fault.
1.6 Function of Magnifying on the Scale of Wave Form

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Through magnifying the scale of the wave form, it can make further
exact testing.
1.7 It can wantonly change the position of the cursor, showing the
direct or indirect distance of fault point and testing point.
1.8 It has the function of changing the speed of communication
depending on the tested cable.
1.9The instrument is portable and with a chargeable battery to
provide power. It is convenient to take and use.
2 Main technique parameters
2.1 Scope of application and using purpose
The instrument can test all kinds of electric cable(voltage of
1KV-35KV) and the Short Circuit, Grounding, Leakage of High
Resistance. High Resistance Flashover, Out Line and Bad Contact
fault on the local cables, frequency modulation communication
cables, coaxial cable and metal aerial cables. It also can test the
length of cable and the spread velocity on the cable.
2.2The longest testing distance is 15KM (100KM for the open-wire
line)
2.3 Testing .dead zone is 1M.
2.4 Resolution of reading is 1M
2.5 Power dissipation is 5VA
2.6 Service condition :
environment temperature 0℃~＋40℃

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terminal temperature －10℃~＋50℃
relative humility 20-90%RH
2.7 Dimension: 275×220×160mm3
2.8 Weigh: 1.8kg
Ⅲ. Low Voltage Impulse Testing Method
1. Principle of Testing
The principle of cable fault testing is based on the asymmetrical
resistance’s reverse on the communication of the electric wave in
the cable.
Based on the theory of Transportation Line, every line has a unique
resistance Zc, which is depending on the structure of the circuit but
not the length of the line. In the symmetrical transportation line, the
resistance input equals the unique resistance at any point. If the
load of terminal equals the unique resistance, the current wave and
voltage wave on the transportation reverse none but absorbed
totally by the terminal. When the resistance at any point is unequal
to Zc, the electric wave reverse all or partly. The scale of reverse
polarity can be expressed by parameter P, the relation is on the
below:
Zcis the resistance of the transportation line
Zois the resistance of the reverse transportation line
P＝
Ur（reflection wave）
Ui（incident wave）
＝
Zo－Zc
Zo＋Zc
（1）

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(1) When it works without fault, Zo＝Zc, P＝0, no reverse.
(2) when the circuit is off line, Zo＝∞, P＝1, it reverse totally and the
polarity of the incoming wave and its reflex are the same.
(3) when the circuit is short circuit, Zo＝1, P＝－1, it minus totally
reverse and the polarity of the incoming wave and its reflex are the
opposite .
When there is an impulse electric wave, the impulse conveys on
the line by the speed of V, and reflex to the input terminal when the
row distance Lxmeets the fault point. The time of the reverse is T,
so the relation is on the below:
V is the speed of the electric wave of the line, and is related to the
linear circuit parameter and constant to an case which can be
detected by the instrument and calculated by computer. When the
displayer show the the impulse and the reverse wave from the fault
point in real time, we can get the time T by providing the
instrument’s time signal. So we can get the location of the fault
point from (2). Different kinds of faults has wave charts as below:
Method of impulse can easily detect the fault in the off line, short
circuit and cable’s low voltage grounding. In the situation of high
resistance fault, for it still shows high resistance in the condition of
low voltage impulse and makes no or few reverse wave. In this
2Lx
＝
VT
（2）
∴Lx
＝
1
2
VT
T

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situation, we need add amount of current or high voltage impulse to
discharge it and get the reverse wave by the short circuit in a wink
by flashover electric arch.
IV. High Voltage DC Flashover Method
When the resistance of fault is really high, before it forms a
constant current tunnnel, it can grandually rise the voltage on the
cable. Reaching some voltage, the fault point is first been sparked
over forming the flashover, and we can use the electric arch added
to the voltage to form a short circuit reverse. The reverse wave at
the input terminal forms the open reverse by the high resistance
resourse. So the voltage reverse many times between the input
terminal and output terminal until it runs out of energy. The grahp of
testing principlewave form of reverse wave are as below:
The distance of the fault point:
Among: T＝t2－t1＝t2－t1＝t2－t1＝……
T
P=1 off line
P=-1 short circuit
P=0 regular
V
A
R3
R2
R1
D
device
Test line
Figure 2
Lx
＝
1
2
V·T

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Theoritically the wave form should be steep square wave, but refer
to the incomplete reverse and circuit comsuption the real wave
becomes smaller and smoother.
V. High Voltage Impulse Flashover Method
When fault point reduces the resistance and forms constant
resistance tunnal, we have to choose the voltage impulse method
for we can not add more high voltage current by the limit of
instrument capacity. High voltage current through sphere gap can
charge the cable until spark-over, and we still use the reverse wave
produced by the flashover electirc arch. At the input terminal of
cable we detect the inductance L to read the reverse wave. The
circuit principle graph is as below. Electric wave reverse at the fault
point and reverse by L at the input terminal, so it forms multiple
reverse. Because of the self-inductance phenomenon, it shows as
open reverse at frist for the resistant effort of L, and shows as short
circuit reverse by the acumulation of current. And the whole circuit
is made of process of discharge by electric capacity C and
inductance L. So at the output terminal the curve shows as a
reducing cosine wave added by several quick impulse reverse
waves. As the graph below. We can get distance of fault from the
internal of reverse wave.
Ideal wave
Real wave
Figure 3

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Fault distance:
T+ΔT≥T , ΔT is time of discharge decay.
VI. Fundamantal Principle and Composition
1. Fundamantal Principle of Instrument
Based on the fault testing principle, when the device is in the trig
mode of flashover, the flashover wave formed by electric arch on
the fault point is random einmal transient wave, so the instrument
should have the function of saving, capture and displaying the
einmal transient wave. The instrument applies the technology of
digital storing using the high speed A/D converter to get sample,
and converts the transient analog signal to digital signal in real time
and saves it in the cache. Then sent the signal to LCD displayer
control circuit after processing in the CPU as time series dot matrix
signal and then shows the sampling parameter on the LED
displayer.
When the instrument in the mode of impulse trigging, it sent
Lx
＝
1
2
V·T
V
A
R3
R2
R1
D
device
Test line
C
L
T+ΔT
T
full wave
expanded wave

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detective impulse to the tested cable and input circuit in certain
cycle. At the same time the A/D works and has the same process of
sampling, storing, processing and displaying as stated before. LED
displayer should have reverse wave form.
2. Composition of the Instrument
Instrument is designed as the core of micro processor and
controlling the signal’s sending, receving and digitalizing
processing. The principle of the operation is as below:
The word done by microprocessor concludes: data sampling, data
storing, data filtration, cursor moving, distance computing, graph
comparing, graph size changing and displaying on the LED. And it
also can depend on need to communicate by the tranportion port
and PC.
Impulse producer forms the a logic impulse of a certain width by the
coding signal from the micro processor. The impulse will be
converted by transmitting circuit to high range and eventually to the
tested cable.
High speed A/D producer is to convert reverse signal on the tested
cable through input circuit sending A/D sampling and finally sent ot
LCD
MicroProcessor
ImpuPro
A/D
power
Input
KB
Test line

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the micro processor.
Keyboard it the window for communication between human and
computer. Opertators can type the command by keyboard to
computer by the testing and then the computer controller complete
some kind of testing.
VII. Panel Controlling and Keymanual’s Function
1. On/ off: control the power of the device on or off. Press the
button, the device has the power and displayer will show the
window of operations.
2. Mode : press is flash over mode, otherwise it is impulse mode.
3. Waveform control: control the wavefrom size.
4. Output: the output line of device connected to the tested
terminal of cable.
5. Transmission speed: The preset speed of the instrument is

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200m / μs. The corresponding value should be entered according
to the actual type of cable. Otherwise, the result will be incorrect.
6. Transmit: Each time pressed, the instrument emits a pulse and
samples.
7. Display scale: Different measurement range corresponds to a
different display scale, that is, the sampling point, according to
different intervals displayed on the screen, the larger of range, the
larger interval, the greater the proportion of display, change the
display scale the waveform can be extended. Adjust the display
scale by pressing the decrease/increase key.
VIII. Instrument use fault test method
1. Fault type detect
Before the test cable fault, first determine the type of fault in order
to determine which test method to use. With the help of a
multi-meter or megger or other tools and on-site experience, you
can prejudge the type of failure.
If the fault type is open, short circuit, poorly contacted, or low
impedance grounded, use low voltage impulse method for
measurement. If it is high resistance fault, you should use high
voltage impulse method. If the fault type is not certain, you can use
the waveform comparison method.
2. Wave velocity calibration
When the measured cable velocity cannot be determined, it must

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be calibrated to ensure the accuracy of fault measurement. The
calibration method is as follows:
1) Prepare a standard cable same type as the cable under test;
2) Connect the standard cable to the output port of the tester;
3) Turn on the instrument power switch;
4) Choose the impulse mode, the upper right corner of the screen
shows "impulse";
5) Adjust the measurement range more than or equal to the length
of the standard cable;
6) Press the "impulse" button to send the test pulse, the screen to
get reflected waves;
7) Press the ►button to move the cursor to the start of the
reflected wave. If the reflected wave is not well discriminated,
adjust the “waveform control” knob to change the amplitude of the
waveform and then retransmit the pulse;
8) Modify the wave speed until the measured distance is equal to
the length of the standard cable, and then note the value for use.
3. fault test
1) Low voltage impulse method
A. Disconnect all equipment from the cable under test
B. Connect the cable under test to the output port of the tester.
C. Turn on the power.
D. Choose the impulse mode.

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E. Enter the wave speed value corresponding to the cable under
test.
F. Adjust the “waveform control” to maximum, press “transmit”,
there is wave on the screen.
G. If there is no reflected wave, adjust the measurement range and
then repeat the pulse, so try several times, until wave reflects.
H. Adjust the gain and retransmit the pulse, make the front of the
most steep reflection wave;
I. Press ◄ or ► to move the measuring cursor to the leading
edge of the reflected wave, and the upper left corner of the screen
shows the fault distance;
J. In order to improve the accuracy, change the waveform
proportion, the waveform is expanded, according to the above
method for precise positioning;
K. The fault type can be judged by the polarity of the reflected
wave.
Short circuit waveform:
Short circuit waveform:

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2) HV DC Flashover Method
A. First working mode at flash over, the transmission speed should
be the wave speed of the cable under test.
B. Application: the resistance of the fault is very high and not
forming a fixed tunnel, under a certain voltage it can create a
flashover discharging fault of the electric cable. Preventative
spark-over testing usually applies this method.
C. The time of the high voltage current flashover method varies,
and the short one can exist for some times. The wave form is
simple, can be easily recognized and with a high accuracy and
value it.
D. The principle graph of the current flashover method is as below.
In the real testing, apply the high voltage equipment and our
high voltage testing production. The connecting graph is as
below too.
V
A
R3
R2
R1
D
device
Test cable
C
L

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T1 voltage adaptor………………………………………………2KVA
T2 high voltage transformer………………….……0～50KV，2KVA
D high voltage silicon stack……………ReV: 100KV，FoV: 100mA
C high voltage capacity……………………………...0.1μF，10KV
The AC/DC meter: 0-300V; The current meter: 100mA;
In the high pressed testing equipment,
Resistance: 30±20/5kΩ;
Output resistance: 500Ω±10%.
E. Turn on the power, the screen lights. Then rise the voltage
gradually by adaptor, and when the fault point has the
phenomenon of flashover, the current in the micro-amp meter
rises heavily and the indicator in voltage meter also alters
heavily. The wave form as below should be on the screen. From
the graph, the interval of t1and t2 should be the distance of the
fault points.
F. The voltage of high voltage flashover testing method could be
as high as thousand or ten thousand voltage and operators
should obey the operation rules like connecting the equipment
to the ground and high voltage equipment’s base line and
grounding line of the equipment should connect to the cable in
lead which is connected to the ground. Connect the lines as 9.3
and check the water resistance and voltage divider resistance in
the high voltage testing.