HVTest HTHL-200A User manual

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Dear Client
Thank you for Purchasing our HTHL-200A Micro Ohmmeter.
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. Functions..............................................................................................6
III. Features...............................................................................................7
IV. Specifications....................................................................................7
V. Panel Layout....................................................................................... 8
VI. Work Principle................................................................................... 8
VII. Operation Methods......................................................................... 9
VIII. Problems and Solutions............................................................ 10
IX. Notes..................................................................................................10
Appendix A：Basic Knowledge about Contact Resistance.... 11
Appendix B：Standard Reference for Conducting Loop
Resistance of Circuit Breaker...........................................................12

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I. Overview
Nowadays Power Systems widely use model QJ44 DC double arm bridge
to measure contact resistance (DC resistance and Loop resistance of
high-voltage circuit breaker) while the minimum current of such model is 1mA
which hardly find the decrease of cross-sectional area of transformers’
conductive circuit conductor. The measurement of loop resistance of high
voltage switchgear is affected by oil layer and oxide between static and
dynamic contact port, so the resistance measurement value will be several
times larger, and can not reflect the true value of contact resistance. Therefore,
the Ministry of Electric Power in national standards SD301-88 "AC 500KV
Electrical Equipment Transfer and Preventive Test Procedure" and new
version of " Electrical Equipment Preventive Test Procedure" stipulate that the
testing current of circuit breaker and isolating switch contact resistance is not
less than 100A to ensure accurate test results.
HTHL-200A Portable Micro Ohmmeter measures up to the latest power
system standards--DL/T845.4-2004 designed for measuring loop resistance of
Switching Control Equipment using High-frequency switching power supply
technology and digital circuit technology. Test current of the Tester is
DC-100mA
Or DC-200mA which is recommended in the national standards. The
tester can measure the loop resistance at those values and display results in
digital. It is high precision and good stability and can meet most power
systems’ requirements in onsite high-voltage switches maintenance and
high-voltage switches factory loop resistance measurement. (It performances
accurately and stably)
II. Functions
HTHL-200A Portable Micro Ohmmeter is suitable for measuring loop
resistance of high-voltage switches in high-precision. It also applies on other

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test occasions that need high current and micro resistivity.
III. Features
(1) High current: For latest power supply technology, the tester can
continuously output high current which overcomes the weakness of
instantaneous current produced by pulsed power. It can effectively
breakdown/puncture the oxide layer of the switches and then get precise
results.
(2) Strong anti-interference ability: The last number of test data will stably
show in the LCD screen only with ±1 error even in strong Interference
situation.
(3) Long service life: All the precise resistances used in the tester can
reduce the temperature’s impact on the measurement results and military
connectors can enhance vibration resistance.
(4) Convenience: Small size, light weight.
IV. Specifications
1. Measurement Range：1～1999μΩ
2. Resolution：1μΩ
3. Test Current ：DC 50A, DC 100A, DC 150A, DC 200A, four fixed
outputs.
4. Work Mode：continuous
5. Measurement Accuracy：0.5%±1d
6. Display：three and a half LCD
7. Power Supply：AC220V±10% 50Hz
8. Work Environment：
Temperature：－10℃～40℃Humidity：≤80 %RH
9. Dimension：370×320×260 （mm）
10. Weight：9.6kg（Accessories excluded）

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V. Panel Layout
Figure 1 Panel Layout diagram
1、 Resistance Display
（μΩ）
2、Ground
3、Power Outlet
4、Power Switch
5、Measurement Switch
6、Current Selection
7、Current Output I－
8、Measurement Input V－
9、Measurement Input V＋
10、Current Output I+
VI. Work Principle
HTHL-200A Portable Micro Ohmmeter bases on the Current-voltage
testing principle that also known as Four-line method testing technology. More
details show in Figure 2.

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Figure 2 Schematic diagram
The current goes through I+ and I- ports to the resistance Rx, current
value can be got from the ammeter I, and the voltage between V+ and V- will
be shown in the voltmeter V. Based on data I and V, the resistance value can
be calculated.
VII. Operation Methods
1. Wire as shown in the Figure 3.
Figure 3 Four-terminal Wiring diagram
2. The junction of panel and test lines should be tightly screwed.
3. You should use Four-terminal wiring method in which current line
should be fasten to I+ and I- ports and voltage line should be fasten to V+ and
V- ports. Current and voltage must have the same polarity.
4. After checking the connection of tester and test lines, access/contact to

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220V AC and start the tester.
5. Adjust the “Current Selection” knob to you need fixed output and then
press the “Measurement Switch” button, the data displayed in the monitor is
the test value of loop resistance. Displaying 1 indicates the loop resistance
value is beyond the measurement range.
6. Completed measurement, please disconnect the power switch and put
the test lines into accessories bag.
VIII. Problems and Solutions
Problems
Solutions
No respond after powering
on
Check if AC power is on
Check the power Cables
Check if the Fuse is Burn out.
Display 0 during
measurement
Check if “Test” button is pressed.
Check if current output lines have poor
contact.
Check if the fixed output of “Current Selection”
is correct
Display actual current
values but resistance value
is evidently larger or 1
( beyond range)
Check if resistance value is too large
Check if current lines places laterally
Check if current output lines have poor
contact or the port connected to the test piece
is oxidized.
IX. Notes
1. Please read the manual carefully before using this tester.
2. Please wire properly as recommended in this manual.
3. This tester cannot measure resistance that is in a live circuit.

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4. Ground should be connected during the use of this equipment.
5. Arbitrary replacement of current lines is forbidden.
6. The tester should be put in ventilated, dry, cool and cleaning place. Pay
attention to humid or erosive gas that may damage this equipment.
Appendix A：Basic Knowledge about Contact Resistance
1. What is contact resistance?
Contact resistance is the additional resistance caused by the connection
of static contact and dynamic contact.
2. What are the components of circuit breaker contact resistance?
Circuit breaker contact resistance is composed of shrink resistance and
surface resistance of static contact and dynamic contact.
3. What caused circuit breaker contact resistance out of work?
1) Contacts are burned because of Short.
2) If circuit breaker contact resistance is poor connected, that will cause
changes in itinerary. Serious Excess load/Overload will cause the contact
pressure or contact area changes.
3) Finished installation, the breaker has not been put into use for a long
time, so the dynamic/static contacts are oxidized and the Surface Resistance
becomes larger.
4) Due to long-term running the spring out of shape, which cause the
contact pressure drop.
5) Long-term operation cause machine wear.
6) For less oil circuit breaker, unqualified insulating oil will lead the
occurrence of acid reaction, the result is the contact surface being eroded. And
insulating oil is mixed with impurities, after breaking the short-circuit current
between dynamic contact and static contact, the residual carbon particles or
metal powder will boost the contact resistance.
4. What can affect contact resistance?
1) Material properties: Resistivity, hardness, chemical properties,

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mechanical strength and resistivity of metallic compound.
2) Contact form: Point contact, line contact and area contact.
3) Situations of contact area: The oxide film formed in contact area (the
Silver exception), whose resistance is larger than that of metal.
4) Contact pressure
5) Roughness of contact area
Appendix B ：Standard Reference for Conducting Loop
Resistance of Circuit Breaker
Model
Loop Resistance
of Each Phase
（μΩ）
Model
Loop Resistance
of Each Phase
（μΩ）
SN1-10
<95
DW1-60G
200
SN2-10G
75
SW1-110
700
SN4-10
50—60
SW2-110I
180
SN4-20
50—60
SW3-110
160
SN4-10G
20
SW4-110
300
SN4-20G
20
SW6-110
180—220
SN5-10
100
SW2-220
400
SN6-10
80
SW4-220
600
SN10-35
<75
SW6-220
<400
DW1-35
550
SW7-220
<190
DW1-60
500
KW1-220
400
DW3-110
1100—1300
KW2-220
170
DW2-110
800
KW3-220
110
KW1-110
150
KW4-220
130
KW3-110
45
DW2-220
1520
KV4-110A
60
DW3-220
1200
DW3-110G
1600—1800
SW6-330
＞600