KEHUI T-H200 User manual

T-H200
DC Resistance Cable Sheath Fault Locator
User Manual
Version 1.2
Kehui International Ltd.
2 Centrus, Mead Lane, Hertford
Hertfordshire, SG13 7GX
United Kingdom
Phone: [phone]
Fax: [phone]
Website: http://kehui.com

T-H200 User Manual Version 1.2 | 2
Legal Notices
The copyright of this material belongs to Kehui International Ltd. No company or individual may
extract, copy or translate this material in any way without the written permission of the copyright
owner.
This product complies with the design requirements for environmental protection and personal
safety.
This product is a professional instrument specially designed for power cable faults. Please do not use
it for any other purpose. The company assumes no responsibility or loss if it is used for other
purposes.
The safety regulations in this user manual should be strictly adhered to.
The storage, use and disposal of the product should be in accordance with the product manual,
relevant contracts or relevant laws and regulations.
As part of Kehui’s continual product development this product is subject to design or technical
changes without prior notice. When product improvement or technical changes occur, you can check
the information through Kehui International Ltd. website https://www.kehui.com.
Disclaimer: Every effort has been made to make this material complete, accurate, and up-to-date. In
addition, changes are periodically added to the information herein; these changes will be
incorporated into new editions of the publication. Kehui International Ltd reserves the right to make
improvements and/or changes to the product(s) and/or the program(s) described in this document
without notice, and shall not be responsible for any damages, including but not limited to
consequential damages, caused by reliance on the material presented, including but not limited to
typographical errors.
NOTE: Windows is a registered trademark of Microsoft.
Revision history:
Data version
Revision date
Revision reason
Person
Version 1.0
2019.06.17
Update, verification and
approval
Tony Yip / Shan
Chao / Gong Shi
Ying
Version 1.1
2020.04.09
Release
BilKib
Version 1.2
2020.09.03
Minor revisions
BilKib
Document number: T-H200_UM_V1.2_EN

T-H200 User Manual Version 1.2 | 3
Table of Contents
1. SAFETY INSTRUCTIONS ..............................................................................................................4
2. INTRODUCTION.............................................................................................................................5
2.1 Product features......................................................................................................................5
2.2 Model number nomenclature ..................................................................................................6
2.3 Technical data.........................................................................................................................6
2.4 Working conditions..................................................................................................................6
3. WORKING PRINCIPLES................................................................................................................6
3.1 DC resistance method.............................................................................................................7
4. COMPOSITION AND APPLICATIONS...........................................................................................8
4.1 Data acquisition unit................................................................................................................8
4.2 Display unit..............................................................................................................................9
4.3 Cable sheath fault test ..........................................................................................................12
4.4 Cable main insulation fault test.............................................................................................16
4.5 Battery charging....................................................................................................................19
5. PACKING LIST - T-H200 ..............................................................................................................20

T-H200 User Manual Version 1.2 | 4
1. Safety Instructions
Safety Note:
This user manual is the basic commissioning and on-site operation guide for
the T-H200. Users should read the entire contents of this manual before
operating the device. The manufacturer of this product is not responsible for
any loss caused by the operator's failure to comply with the operating
procedures described in this manual or for any contravention of safe working
procedures.
Meaning of the
manual symbols
Important instructions concerning personal safety, operating procedures,
technical safety etc., are marked with the following symbols:
Symbol
Meaning
Indicates the presence of high voltage which
presents a potential hazard that could result in fatal
or serious injury
Indicates a potential hazard which could result in
personal injury or damage to equipment
Indicates that it contains important information and
useful guidance for using this product. Failure to
heed this information will result in the test not
functioning properly.
Indicates that this is a useful guideline based on field
practice.
Use of
accessories:
To ensure the safe and reliable use of this instrument, only use spare parts
approved by Kehui. The use of items from other sources may invalidate the
warranty.
Repair and
maintenance:
This instrument must be repaired and maintained by Kehui or its authorised
agents. If there are any questions relating to maintenance, contact
[email protected]

T-H200 User Manual Version 1.2 | 5
2. Introduction
The T-H200 DC Resistance Cable Fault Locator, uses the advanced DC resistance method to
locate external protective sheath faults and main insulation faults on power cables. It is
designed for use with a high voltage generator and comprises a signal acquisition unit and an
Android smart tablet, which acts as the user interface. The tablet is connected to the main
unit using a low-powered BluetoothTM signal. The associated tablet APP guides the user
through on-site safety, correct wiring and step-by-step operation, to ensure the accuracy of
the result. After the test, a summary report is produced to simplify user documentation.
2.1 Product features
This product has the following features:
•Through an advanced DC resistance method, the equipment can locate low and high
resistance external sheath faults for single core power cables, and main insulation
failures for 3-core cables.
•The intelligent tablet APP guides the user through the wiring connection, testing and
report generation.
•The test leads use different coloured wire clamps and terminals which, together with
the APP’s wiring diagram, help to ensure correct wiring.
•The acquisition unit’s voltage withstand is up to 45kV DC, helping to ensuring
operational reliability.
•An undervoltage alarm function is available to provide a low battery-charge warning.
•The unit is compact and light weight, making it easy to carry.
•Communication between the acquisition unit and the tablet is through a safe and
reliable BluetoothTM connection.
Figure 2.1 –T-H200 unit and tablet controller

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2.2 Model number nomenclature
The model number nomenclature is as follows;
2.3 Technical data
•Working mode：cable sheath fault location, cable insulation fault location
•Current measuring range：0 to 150mA
•Current resolution：10µA
•Current accuracy：1%
•Voltage measuring range：0 to 50mV
•Voltage resolution：10µV
•Voltage accuracy：(U±20%) µV
•Bluetooth range：10m
•Power source：Polymer Lithium Ion battery pack，nominal voltage 7.4V。
•Charger：Input AC 220V，50Hz，Voltage 8.4V, Charging current 2A，Charging time 8
hours。
•Size：216mm×152mm×95mm
•Weight：2kg
2.4 Working conditions
•Working temperature -10℃to +50℃
•Relative humidity 25℃(20 - 90)%RH
•Atmospheric pressure 86 - 106kPa
3. Working Principles
Most cables above 35kV have a single-core. When load current passes through the cable, an
inductive voltage appears at both ends of the protective layer (aluminium or other types of
metallic shield). In order to avoid circulating current, which results in heat loss and
accelerated aging of the cable, multi-point grounding (or earthing –subsequently referred to
as grounding) of the metallic shield is not allowed and only one end of the shield is
grounded.
The outer insulation of the protective layer (the sheath) is made of plastic, paper or other
insulating materials, which is susceptible to external damage causing ground faults involving
the protective layer. Therefore, failure of the protective layer of a high voltage single-core
cable, known as a sheath fault, is a common fault phenomenon.
T- 200H
Test Equipment
Cable Sheath Fault
Model version

T-H200 User Manual Version 1.2 | 7
Power cables at 35kV and below usually have three-cores, the insulating layers are relatively
thick and most of the insulation faults are either high resistance or flashover faults.
In both cases, the only available return path from the fault position is through the ground
surrounding the cable, which does not provide a return path suitable for using conventional
fault-finding equipment such as surge generators or TDR units. Hence alternatives have to
be found to measure the distance to the fault.
Traditionally, the DC bridge method has been used for sheath fault location which is simple
in operation, however, the accuracy is affected by the resistance of the fault and the
connecting wire, which may lead to significant errors.
3.1 DC resistance method
The DC resistance method calculates the fault distance by measuring the DC resistance from
the measuring point to the fault point. Unlike the traditional DC bridge method, this is not
affected by the resistance of the fault or the connection leads, hence the accuracy is higher.
The DC resistance method can be used to test the resistance of the main insulation and the
protection layer. The T-H200 uses this principle to find faults on high-voltage cable sheaths
and the main insulation which exhibit low grounding resistance, and joint failure.
The principle of the DC resistance test is shown in Figure 3.1. The faulty cable shield is
connected to a healthy core or to another healthy shield at the remote end. Using the
negative terminal of the DC power supply E, the current i is injected into the cable shield and
the DC voltage U1 is measured across the two line terminals. There is no current flow from
the fault point to the near end of the healthy shield where the voltage is measured,
therefore, they are of equal potential. The measured voltage U1 is effectively the voltage
drop across the faulty section of the shield. The DC resistance between the measurement
point and the fault point can thus be calculated as: R1 = U1/i.
Assuming the resistance per unit length is 0（Ω/km), the distance can be calculated as：
L= R1/ 0
E
mV
RF
Faulty Protective sheath
Healthy core or sheath
U1
mA
I
Figure 3.1 - DC Resistance method for sheath fault
detection
i

T-H200 User Manual Version 1.2 | 8
4. Composition and Applications
4.1 Data acquisition unit
The unit is shown below, with the lid removed for clarity:
The front panel comprises the following elements:
•The <On/Off> switch controls the power supply. When the switch is on, the “Power
indication” will be lit.
•Charger terminal –for connection to the output of the charger. The <red> indication
shows that charging is in progress, the <green> indication shows that charging is
complete.
•Bluetooth indication : When the instrument is switched on, the Bluetooth light is
flashing. After the connection with the tablet is established, the light will remain steady.
•4 coloured sockets –Each wiring socket has a different colour, related to the colour
scheme of the wiring diagram shown in the display unit (see figure 3 and 5).Theyare
labelled:
−Auxiliary wire (black), connected to the healthy cable
−Faulty shield (yellow), connected to the faulty cable shield
−High voltage (red) connected to the high-voltage generator (e.g. Kehui T-100C)
−Faulty shield (green). connected to the faulty cable shield (together with the
yellow lead).
Note: The HV generator output is normally negative, the connection should be in accordance
with the colour scheme shown in the wiring diagram.
Figure 4.1 –T-H200 Front Panel

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4.2 Display unit
The display unit is an Android tablet. A specially designed APP operates as the background
software, which receives test signals transmitted through Bluetooth. Its main functions are:
•Receiving test signals
•Operational step-by-step guidance
•Data storage
•Results display
•Test report production
4.2.1 Tablet Preparation
Fully charge the tablet using the charger supplied (do not use any other charger for this
purpose).
4.2.2 Turning on the tablet PC
•Turn on the unit by pressing the “on” button for several seconds (below (i)).
•This should result in the screen shown in (ii). Do not touch the screen until
advised below (i)
•This screen will remain for about 30s while the unit boots-up.
Figure 4.2 –Tablet
Controller
Figure 4.3 –Tablet
“On” button
Figure 4.4 –Tablet
boot-up - i

T-H200 User Manual Version 1.2 | 10
•It will then automatically change to (ii) with the “Handheld” logo swiping across
the screen.
•
•After a few seconds it will stabilise and then change to the screen shown
below (iii):
•
•When this screen appears, put your finger at the bottom of the screen and swipe
upwards, the screen should change to (iv)
•Put in the PIN number (initially 1234) using the touch screen and press ✓, the
screen changes to (v), with the Kehui T-H200 APP highlighted.
Figure 4.5 –Tablet
boot-up -ii
Figure 4.6 –Tablet
boot-up -iii
Figure 4.7 –Tablet
boot-up -iv PIN Code
Figure 4.8 –Tablet
boot-up –v APP Icon

T-H200 User Manual Version 1.2 | 11
•Touch the Kehui symbol and the APP
will open (vi). If the Kehui symbol is not
there, swipe the screen left or right, as
it may be on a different page.
•The App start page (vi) will appear.
4.2.3 Turning on the T-H200
The T-H200 unit can be turned on or off by pressing the power on/off switch on the front
panel. The detector power indicator lights up when the detector is turned on.
[Warning] The battery must be charged using the dedicated charger. Using other chargers
that do not meet the exact parameters, may cause damage to the instrument.
4.2.4 Bluetooth Connection
With the detector and tablet PC powered on, click the device name T-H200 in the pop-up
pairing dialogue box, enter the T-H200 detector default PIN code 1234, then click the tick ✓
to complete the Bluetooth pairing and connection of the tablet and detector. Once the
Bluetooth connection is successful, you should exit to the tablet desktop interface. The
operation interface is as follows:
[Note]
This step only needs to be performed once. After the device is successfully paired, it is not
necessary to repeat this operation. However, the pin number will be required to access the
tablet after a period of inactivity.
Figure 4.9 –Tablet
boot-up vi App Start
page
Figure 4.10 –Tablet boot-up vi App Start page

T-H200 User Manual Version 1.2 | 12
4.2.5 Launch APP
After clicking the T-506 APP icon on the desktop, the user will see the APP start-up
screen as shown in the figure below.
To connect the unit, enter the settings menu of the Android device on which the App is
loaded. Select the Bluetooth settings (usually in “Device Connectivity”), ensure Bluetooth is
activated and that the device is visible. If the T-H200 is switched on, it should appear as an
available device and tapping on the T-H200 device name will bring up a password request.
The password is “1234”, entering this will connect the device and allow it to be used as the
T-H200 control panel.
The home page of the APP (Figure 4.14) shows two functional selections: cable sheath fault
test and cable main insulation fault test. The user can select and open the corresponding
page according to the different cable fault types.
4.3 Cable sheath fault test
After confirming that the fault is a cable sheath fault, select the “Cable sheath fault test”
mode and follow the instructions below.
4.3.1 Cable shield resistivity test
First Step: Resistivity test Connections
The operator interface shows the connection diagram for the resistivity test. The colour
scheme of the diagram should be followed precisely, using the different coloured connectors
provided. Note that “HV” shown on the APP circuit diagram, refers to a High Voltage
generator, such as the Kehui T-100C or Kehui T-305E (in DC mode).
i. Before connection, make sure the cable is completely disconnected and is fully discharged.
Residual charge on the cable can make it extremely dangerous.
ii. Ensure that the battery charger is not connected to the T-H200 (n.b. if the battery completely
discharges during testing, the T-H200 should be completely disconnected before recharging)
Figure 4.11 –Tablet
boot-up vi App Start
page

T-H200 User Manual Version 1.2 | 13
iii. Connect the auxiliary line (the cable core) and the healthy shield together at the remote end
with a wire.
iv. Connect the current measurement faulty shield terminal (green connector) to the healthy
shield.
v. Connect the current measurement HV terminal (red connector) to the HV generator’s HV
capacitor output terminal.
vi. Connect the current measurement faulty shield terminal (green connector) to the healthy
shield.
vii. Connect the voltage measurement auxiliary wire terminal (black connector) to the auxiliary
line (cable core).
viii. Connect the voltage measurement faulty shield terminal (yellow connector) to the healthy
shield.
ix. Ground the HV generator’s grounding terminal to the working ground (or the auxiliary
ground).
x. Ground the protective ground of the HV generator.
xi. The protective ground and the working ground must be separated.
Second Step：Resistivity measurements
After entering the screen shown in Figure 4.18, the interface will show the precautions for
HV operation. It will display the "Test current" and "Test voltage" values in real time, and the
instrument will automatically calculate the "full length resistance".
Figure 4.13 –Cable sheath fault test
showing actual equipment
Figure 4.12 –Cable sheath
fault test

T-H200 User Manual Version 1.2 | 14
30.87
30.87
1059
1059
30.87
34.3
0.0599
573
Operation of the HV generator when using the Kehui T-100C (refer to the T-100C manual for
full instructions):
i. For the “mode of operation” select “DC” by pressing the CYCLIC/DC button.
ii. Reduce the HV output (OUTPUT ADJUST) to zero by turning it fully anti-clockwise.
iii. Switch on the power supply.
iv. Press the “START” button to engage the HV output. The indication light will be on, and there
is a hissing sound.
v. Slowly rotate the Output Adjust knob to increase the output HV voltage, observing both the
voltmeter and the ammeter. When the current reaches 50-100mA, stop raising the HV
voltage.
vi. On the tablet APP, select “cable length” and enter the exact length of the cable, the APP will
calculate the “resistivity” automatically, and store the value for the next stage of operation.
Note that the T-100C is the preferred power source for the T-H200, however it will also work
with other suitable high voltage sources and can be powered from the Kehui T-305E surge
generator, used in DC mode. Note that the output must be negative.
Figure 4.14 –Resistivity
measurement screenshot
Figure 4.15 –T-100C front panel

T-H200 User Manual Version 1.2 | 15
4.3.2 Cable sheath fault distance measurement
First Step：Connection
The display in Figure 4.20 shows the connection diagram. The connection needs to be exactly
as shown in the diagram.
Before connection, make sure that the cable is completely disconnected and is fully
discharged. Residual charge on the cable can make it extremely dangerous.
i. Connect the auxiliary line (either the cable core or the healthy shield of another cable) with
the faulty shield.
ii. Connect the rest of the set-up following the colour scheme of the connection diagram.
Second Step: fault distance measurement
Slowly increase the DC HV voltage on the HV generator (e.g. Kehui T-100C) until the test
current is approximately 50 - 80mA. In the screenshot shown in Figure 4.21, the "Test
current" and "Test voltage" are displayed in real time and the instrument automatically
calculates the "faulty section resistance". The cable resistivity obtained previously will be
used to calculate the "fault distance” automatically.
Figure 4.16 –Cable sheath
fault location connection
diagram

T-H200 User Manual Version 1.2 | 16
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35.9
47.7
0.0599
795
4.4 Cable main insulation fault test
After confirming that the fault is in the cable’s main insulation, select the “Cable main
insulation fault test” mode and follow the instructions provided.
4.4.1 Cable resistivity test
First Step: Resistivity test Connections
The operator interface shows the connection diagram for the resistivity test (Figure 4.22).
The colour scheme of the diagram should be followed precisely using the different coloured
connectors provided.
Figure 4.17 - Fault distance measurement
Figure 4.18 - Main insulation resistivity
test connection diagram

T-H200 User Manual Version 1.2 | 17
The following procedure should be followed:
i. Before connection, make sure the cable is completely disconnected and is fully discharged.
Residual charge on the cable can make it extremely dangerous.
ii. Connect the auxiliary line (a healthy cable core, e.g. the first core) to another healthy cable
core (e.g. the second core) at the remote end.
iii. Connect the current measurement HV terminal (red connector) to the HV generator’s (e.g.
Kehui T-100C) HV capacitor output terminal.
iv. Connect the current measurement faulty shield terminal (green connector) to the second
core.
v. Connect the Voltage measurement auxiliary wire terminal (black connector) to the auxiliary
line (first core).
vi. Connect the voltage measurement faulty shield terminal (yellow connector) to the second
core.
vii. Ground the HV generator’s earthing terminal to the working ground (or the auxiliary ground).
viii. Ground the protective ground of the HV generator.
ix. The protective ground and the working ground must be separately earthed.
Second Step：Resistivity measurements
After entering the APP page shown in Figure 4.23, the interface will show the precautions for
the HV operation. It will display the "Test current" and "Test voltage" values in real time, and
the instrument will automatically calculate the "full length resistance".
5059
43.87
0.4865
237
115.4
Figure 4.19 - Resistivity measurements

T-H200 User Manual Version 1.2 | 18
Operation of the HV generator：
i. For the “mode of operation” Select “DC”.
ii. Reduce the HV output to zero.
iii. Switch on the power supply.
iv. Press the “HV output” button to engage the HV output. The indication light will be on, and
there is a hissing sound.
v. Slowly rotate the “HV adjust” knob to increase the output voltage, observing both the
voltmeter and the ammeter. When the current reaches 50-100mA, stop raising the HV
voltage.
vi. Select “cable length” and enter the exact length of the cable, the APP will calculate the
“resistivity” automatically, and store the value for the next stage of operation.
4.4.2 Cable main insulation fault distance test
First Step: Connection
The display shows the connection diagram. The connection needs to be exactly the same as
in the diagram.
i. Before connection, make sure that the cable is completely disconnected and is fully
discharged. Residual charge on the cable can make it extremely dangerous.
ii. Connect the auxiliary line (a healthy cable core) and the faulty core at the remote end
together.
iii. Connect the rest of the set-up according to the colour scheme of the connection
diagram
Figure 4.20 - Main insulation failure test
connection diagram

T-H200 User Manual Version 1.2 | 19
1560
30.6
0.4865
104
50.98
Second Step: fault distance measurement
Using the output control, slowly increase the DC voltage on the HV generator until the test
current is approximately 50 - 80mA. In the screenshot shown in Figure 4.24, the "Test
current" and "Test voltage" are displayed in real time, and the instrument automatically
calculates the "faulty section resistance"; the Cable resistivity result obtained previously will
be used to calculate the" fault distance automatically."
4.5 Battery charging
The data acquisition unit is powered by a rechargeable lithium battery, which provides 5
hours of continuous operation. When the battery voltage is lower than the nominal working
voltage, an alarm will notify the user to charge the battery. If the battery is not recharged,
further usage will eventually cause shut-down of the instrument.
Always ensure that the charger supplied by Kehui for this device is used to charge the
battery
Due to airline regulations, the unit may be shipped with the battery disconnected. When the
unit is first unpacked, plug the charger into a suitable power outlet and insert it in to the
charger socket on the detector and press the on/off switch. If the unit’s Power light does not
illuminate, it is probable that the battery is disconnected. If this happens, it will be necessary
to remove the unit from its case and reconnect the battery jumper.
Figure 4.21 - Main insulation
fault distance calculations

T-H200 User Manual Version 1.2 | 20
5. Packing list - T-H200
No.
Materials
Quantity
1
T-H200 Sheath Fault Locator (data
acquisition unit)
1
2
Tablet with charger
1
3
Grounding Clamp
1
4
8.4V 2A Charger
1
5
Test Lead
1
6
Manual
1
Kehui International Ltd is a company registered in England and Wales with Company Number 10283200