HVTest HTHL-100B User manual

1
Dear Client
Thank you for Purchasing our HTHL-100B 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

2
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

3
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.

4
－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.

5
Contents
1、Overview.............................................................................................. 6
2、Functions................................................................................. 7
3、Features...................................................................................7
4、Specifictions............................................................................. 8
5、Panel Layout............................................................................ 9
6、Measurement Principle........................................................... 10
7、Operating Method...................................................................10
8、Matters Needing Attention.............................................................. 12
9、Fault Phenomenon And Elimination..............................................12
10、Packing List..................................................................................... 14
Appendix 1: Basic knowledge of contact resistance.错误！未定义书签。
Appendix 2: Circuit Breaker Conductive Loop Resistance Standard
Reference Value.............................................................. 错误！未定义书签。

6
1.Overview
At present, the measurement of contact resistance in the power
system generally uses the conventional QJ44 type double-arm DC
bridge, and the test current of this type of bridge is only mA level, it
is difficult to find the defect of reducing the cross-sectional area of
  the loop conductor, and the contact of the high-voltage switch
conductive loop is measured. In the case of resistance, the
measured value is somewhat larger due to the influence of the oil
film and the oxide layer between the contacts, and the contact
resistance value cannot be truly reflected. To this end, the Ministry
of Power Standard SD301-88 "AC 500KV power equipment
handover and preventive test procedures" and the new "Power
Equipment Preventive Test Procedures" to make the measurement
current of the circuit breaker, isolation switch contact resistance is
not less than DC 100A, To ensure accurate test results.
The instrument is designed according to the latest power standard
DL/T845.4-2004 of the People's Republic of China, using
high-frequency switching power supply technology and digital
circuit technology. It is suitable for the measurement of the loop
resistance of switch control devices. The test current is DC 100A
and 200A recommended by national standards. The loop
resistance can be measured directly at a current of 100A, or the
loop resistance can be directly measured at a current of 200A. The

7
final test results are displayed numerically. The instrument has
accurate measurement and stable performance, and meets the
requirements of on-site high-voltage switch maintenance and
high-voltage switch factory loop resistance test in power and power
supply departments.
2.Function
The instrument is suitable for high-precision measurement of
high-voltage switch contact resistance (loop resistance), and is also
suitable for other applications requiring high current and
micro-resistance measurement.
3.Features
1. Large current: Using the latest power technology, it can
continuously output large current for a long time, overcomes the
shortcomings of the pulsed power supply instantaneous current,
can effectively penetrate the switch contact oxide film, and obtain
good test results.
2. Strong anti-interference ability: Under severe interference
conditions, the last bit of the LCD screen can be stable within ±1
word range, the reading is stable and the repeatability is good.
3. Long service life: All high-precision resistors are used to

8
effectively eliminate the influence of ambient temperature on the
measurement results. At the same time, the use of military
connectors enhances the anti-vibration performance.
4. Easy to carry: small size and light weight.
4. Specifictions
1. Measurement range: 1 ~ 1999μΩ
2. Discrimination: 1μΩ
2. Test current: DC 50A, 100A two-speed fixed output
3. Measurement accuracy: 0.5% ± 1d
4. Working mode: continuous
5. Display mode: three and a half LCD
6. Working power supply: AC220V±10% 50Hz
7. Ambient temperature: temperature - 10 ° C ~ 40 ° C humidity ≤
80 % RH
8. Volume: 300 (length) × 290 (width) × 220 (height) mm3
10. Quality: 6kg (without accessories)

9
5.Panel Layout
Figure 1 Panel structure
1.Resistance display
（μΩ）
2、Grounding Rod
3.Current Output I
＋
4、Measurement
input U＋
5.Measurement input
U－
6、Current Output
I－
7、Power outlet
8、Power switch
9、Test button
10.Current Selection
Switch

10
6.Measurement Principle
This instrument adopts the principle of current and voltage
method, also known as four-wire method test technology. The block
diagram of principle is shown in Figure 2.
Fig. 2 Test schematic diagram
By the current source through the "I+, I-" two ports (also known as
the I-port), to supply the measured resistance Rx current, the size
of the current has ammeter I read out, Rx voltage drop "U+, U-" two
ports (also known as V-port) take out, by the voltmeter V read out.
Through the measurement of I and U, the resistance of the tested
resistance can be calculated.
7.Operating Method
1. Connect according to the figure three wiring method.

11
4 terminal wiring diagram Wrong wiring method
Fig. 3 and 4 terminal wiring diagram
2. The connection between the instrument panel and the test line
should be tight and there should be no looseness.
3. It should be wired according to the four-terminal method, that is,
the current line should be clamped on the outside of the test object,
and the voltage line should be clamped inside the test object. The
current and voltage must be the same polarity.
4. After checking and confirming the error, connect 220V AC, close
the power switch, and the instrument enters the power-on state.
5. Adjust the “Current Selection” knob to select the current gear to
be selected, and then press the “Measure” button. The resistance
meter display value is the measured loop resistance value. If 1 is
displayed, it indicates that the measured loop resistance value is
out of range.

12
6. After the measurement is completed, disconnect the power
switch, and collect the test cable clamp and put it into the
accessory bag.
8.Matters Needing Attention
1. Please read the instructions carefully before using the
instrument.
2. Please follow the correct wiring method on the instruction
manual.
3. This instrument must not test the loop resistance in the live
loop.
4. The instrument must be reliably grounded during use.
5. The user of the current line must not be replaced at will.
6. When the instrument is not in use, it should be stored in a
ventilated, dry, cool, clean place, pay attention to moisture and
corrosion-proof gas.
9 Fault Phenomenon And Elimination
Fault phenomenon
Troubleshooting
No reaction after power-on,
Check for AC power supply
Check power cable

13
no display on LCD screen
Check whether the fuse in the base of
the fuse is blown
The resistance value is
displayed at 0.
Check if the "test" key is pressed
Check whether the current output line
is well connected and not in good
contact.
Check that the "Current Selection" key
is selected correctly
The resistance value is
shown to be significantly
larger or to be 1 (over range)
during the test.
Check if the measured resistance is
too large
Check whether the voltage input line is
connected to the inside of the current
output line
Check whether the voltage output line
is connected properly and whether the
tested joint is oxidized

14
10 Packing List
Appendix 1: Basic knowledge of contact resistance
1. What is contact resistance?
The contact resistance is an additional resistance that occurs when
the stationary contact and the movable contact are in contact with
each other.
2. What are the components of the circuit breaker contact
resistance?
It consists of two parts: the shrinkage resistance and the surface
1、Host
1
2、Special test line (two high current lines 6m, two
high current test clips, two voltage test lines 6m)
1
3、Ground wire
1
4、5A Fuse
3
5、Accessory package
1
6、AC220V Power Cord
1
7、Instruction manual
1
8、Certificate
1
9、Inspection report
1

15
resistance of the contact part of the moving and static contacts.
3. What is the reason for the failure of the circuit breaker contact
resistance?
- The contact burns out when a large short-circuit current is broken.
- Due to poorly adjusted mechanism, the stroke is not fixed,
resulting in a change in stroke. When the overtravel is severely
unqualified, the contact pressure or contact area changes.
- After the circuit breaker is commissioned and installed, it has not
been put into operation for a long time, so that the surface of the
moving and static contacts is oxidized and the contact surface
resistance is increased.
- Long-term operation deforms the spring and reduces the contact
pressure.
- Mechanical wear caused by long-term operation of the
mechanical part.
- For oil-less circuit breakers, it may also be acidic due to the acid
value of the insulating oil, eroding the contact surface. Or floating
impurities in the oil, after the short-circuit current between the
moving and static contacts. Residual particulate carbonaceous,
metal powder, increases contact resistance.
4. Factors affecting contact resistance?
- Material properties: electrical resistivity, hardness, chemical
properties, mechanical strength and electrical resistivity of metal
compounds.

16
- Contact form: point contact, line contact, face contact.
- Contact surface condition: When the contact surface forms an
oxide film (except for silver), the oxide film is much larger than the
metal itself.
- Contact pressure.
- the roughness of the contact surface.
Appendix II: Circuit Breaker Conductive Loop
Resistance Standard Reference Value
Model
Loop
resistance per
phase
（μΩ）
Model
Loop
resistance per
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

17
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