DC resistance measuring instrument

PC36CDC resistance measuring instrumentIntroduction to Performance Characteristics:

PC36 seriesDC resistance measuring instrumentIt is a specialized instrument for measuring the DC resistance of wire and cable conductors, and the technical performance of the instrument should fully meet GB/T3048.4Test method for electrical performance of wires and cables Direct current resistance test of conductor The technical requirements for measuring equipment include fast, accurate, stable readings, and easy use. It is an updated product of QJ57 and QJ36 electric bridges. Compared with similar digital micro ohmmeters, this instrument has the following characteristics:

1.1 High measurement sensitivity and resolution.200μ OmegaThe maximum resolution of the gear range is 0.01μ Omega10^-8Ω), which has improved the highest resolution compared to existing digital micro ohmmeters10 times.PC36CDC resistance measuring instrumentThe device adopts a specially designed high-sensitivity and low-noise nanovolt amplifier, with a voltage sensitivity of 100nV (0.1MV)This indicator has reached the technical level of a 6 1/2 digit digital voltmeter. The instrument is in the "low current TLO" measurement state (low measurement current, high sensitivity)Capable of measuring sensitivity and resolution, using10A current measurement 100mm²Copper wire with a cross-section of 1 meter, with 5 valid readings, measuring 1000mm²A copper wire with a cross-section of 1 meter also ensures 4 effective readings, which is an order of magnitude higher than existing digital low resistance meters. It is particularly suitable for measuring ultra large cross-section wires and ultra small cross-section fine wires.

1.2 Multi current measurement function.The various ranges of this instrument are set with different measurement currents to choose from, which are indicated on the instrument panel. This performance overcomes the shortcomings of current measurement that cannot be adjusted by digital meters and some bridges (such as QJ57), and the heating of the measured conductor caused by excessive current in certain gears. In order to achieve multi current measurement, the instrument adopts an innovative digital proportional measurement circuit, which works similarly to an electric bridge. Compared to the commonly used constant current source in current digital micro ohmmeters—The voltage meter method is different, and the final expression of the reading of this instrument is independent of the measured current, greatly reducing the accuracy requirements for the constant current source, while improving the accuracy and stability of the instrument measurement.

1.3 Rate current measurement function.In order to facilitate the implementation of the method in GB/T 3048.4, Article 5.6, which uses two measuring currents with a ratio of 1:1.41 to test the resistance value of the sample separately and determine whether the temperature rise exceeds the standard, this instrument is equipped with three levels of current with a ratio of 0.707:1.00:1.41 for switching, avoiding the loss of measurement accuracy and resolution caused by changing the range gear to reduce the measuring current.

1.4 External thermoelectric balance function.In order to reduce the influence of external contact potential and thermoelectric potential on the measurement results, this instrument is equipped with an external potential balance adjustment device. This method isGB/T 3048.2 Test methods for electrical properties of wires and cables - Test for electrical resistivity of metallic conductor materialsOne of the recommended methods in section 6.5.3.

1.5 Reverse current measurement functionAccording to Article 5.5 of GB/T 3048.4, when the resistance of the sample is less than 0.1When Ω, the current should be measured again in reverse and the arithmetic mean should be taken. In the bridge method, this function is achieved by switching the external commutation switch, while digital micro ohmmeters usually do not allow current reversal and cannot achieve the standard operation requirements. This instrument adopts a specially designed bidirectional current protection circuit, which allows for Reverse current measurement is carried out, and a high-power commutation relay is installed inside the instrument. The current commutation operation is implemented through a panel switch, which is simple to operate and easy to use.

1.6 Manual temperature correction function for copper and aluminum wires (PC36C). When the experimental environment temperature is between 15-25Within the temperature range, by settingPC36CThe temperature correction switch of the instrument will measure the resistance value of the copper or aluminum wire according toGB/T 3048.4The recommended formula automatically converts the wire to a reference temperature of 20 degrees CelsiusThe resistance value at ℃.

1.7 Temperature measurement function and automatic correction function for conductor temperature（PC36E）Our company has established first-class platinum resistors

Standard thermometer7 1/2High precision micro ohmmeter with stability achieved0.01A high-performance conductor resistance measuring instrument has been newly developed in a thermal laboratory based on a constant temperature furnace at ℃PC36EIt can accurately measure the true temperature of the conductor and directly display the reference temperature after temperature correction20The resistance value of the conductor at ℃.

PC36EThe emergence of this technology has made the operation of conductor resistance testing the most simplified, achieving one-step completion of resistance measurement, temperature measurement, and temperature correction, replacing the traditional three operation steps, greatly saving manpower and material resources, and having higher temperature correction accuracy. Instrument supply5The temperature coefficient of commonly used materials can be0-40Accurate temperature correction within the temperature range of ℃ greatly reduces the requirement for environmental temperature control range during conductor resistance measurement. It can be used not only in laboratories but also in workshop sites, directly measuring on coiled cables using bridge fixtures1The resistance value at a distance of meters avoids the loss and waste of metal materials caused by cutting off sampling, while also saving time and manpower.

1.8 High accuracy and long-term stabilityThis instrument has the highest accuracy among similar instruments. The internal standard resistor is made of precision manganese copper material and has undergone a special long-term aging process. It has the same low temperature coefficient and annual stability as the BZ3 series standard resistor. The high sensitivity potential input terminal of the instrument adopts a low thermal potential, long-life silver switch and a low thermal potential gold-plated connector, which can ensure the accuracy and long-term stability of the measurement.

2 PC36CDC resistance measuring instrumentBasic Parameters

The basic parameters of the instrument are shown in the table1

Table 1 Basic Parameters

3 Technical Requirements

3.1 Environmental conditions for instrument use

3.1.1 Environmental temperature: 0-40℃

3.1.2 Relative humidity not exceeding 85% RH

3.1.3 Power Supply: 220V±10%, 50Hz±2Hz

3.1.4Except for the geomagnetic field, there are no electromagnetic fields such as electric pulses or sparks

3.2 Basic error in resistance measurement

The basic errors of each range of the instrument are shown in the table2

Table 2 Basic Error

among whichR_X: Meter reading value (resistance reading) R_m: Measured full range value

3.3 Accuracy level of resistance measurement

The accuracy level and maximum allowable error of each range of the instrument are shown in the table3

Table 3 Accuracy level and maximum allowable error

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3.4 rated current

The rated current nominal values for each measurement gear of the instrument are shown in the table4.

Table 4 Rated current nominal values

3.5 Bidirectional current measurement

After eliminating the thermoelectric potential deviation of the measurement circuit, the difference between the measurement results of the instrument under forward current and reverse current shall not exceed the basic error of the instrument1/2.

3.6 Copper aluminum wire temperature correction, manually input ambient temperature (PC36C):

3.6,1Temperature correction range: set value of ambient temperature15.0—25.0℃, minimum step value0.1℃。

3.6.2 Temperature correction characteristics: When the material of the measured resistor is copper or aluminum, the temperature correction factorK_tComplies with the following formula:

K_t= 1/ [1+0.004( t-20 )] = 250 / (230 + t )

Among them:tFor the ambient temperature

3.6.3 Instrument indication valueR_X =R₂₀=K_t*R_t

among whichR₂₀：20Resistance value at ℃R_tThe ambient temperature istResistance value at time

3.7Automatic temperature measurement and temperature correction (PC36E):

3.7.1Temperature measurement range:0—40℃,Resolution:0.01℃。

3.7.2 Temperature measurement accuracy:

Between 15-25Within the temperature range of ℃, the temperature measurement error shall not exceed ±0.05℃;

Between 10-30Within the temperature range of ℃, the temperature measurement error shall not exceed ±0.1℃;

at0—40Within the temperature range of ℃, the temperature measurement error shall not exceed ±0.15℃。

3.7.3 Temperature correction characteristics: Temperature correction coefficientK_tComplies with the following formula:

K_t= 1/ [1+a]₂₀( t-20 )] .

Among them:t: Sample temperature

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alpha₂₀Temperature coefficient of resistance of wire material (20)℃), commonly used conductor materialsalpha₂₀The data is:

Copper and aluminum bars:alpha₂₀ =3.93×10^-3/℃； Hard aluminum wire:alpha₂₀ =4.03×10^-3/℃；

Annealed aluminum wire:alpha₂₀ =4.07×10^-3/℃(The above data comes from Appendix B of GB/T 3048.2)

Hard copper wire (thick, diameter greater than or equal to 2mm):alpha₂₀ =3.81×10^-3/℃；

Hard copper wire (thin, diameter less than 2mm):alpha₂₀ =3.77×10^-3/℃；(The above data comes from GB/T 3953)

The PC36E panel is equipped with the temperature coefficients of the five types of conductor materials mentioned abovealpha₂₀The selection switch,alpha₂₀The numerical value is displayed on the instrument screen.

3.7.4 Instrument indication valueR_X =R₂₀=K_t*R_t

among whichR₂₀：20Resistance value at ℃R_tThe ambient temperature istResistance value at time

3.7.5Additional temperature correction error

3.7.5.1Temperature correction static error:

After the ambient temperature is sufficiently stable and the measured sample is placed in the measurement environment for a sufficient period of time, the additional temperature correction error is the instrument temperature measurement error and the material temperature coefficientalpha₂₀The product of:

Between 15-25Within the temperature range of ℃, the additional error of temperature correction shall not exceed ±0.02%;

Between 10-30Within the temperature range of ℃, the additional error of temperature correction shall not exceed ±0.04%;

Between 0-40Within the temperature range of ℃, the additional error of temperature correction shall not exceed ±0.06%.

3.7.5.2Temperature correction dynamic error:

When the ambient temperature fluctuates or there is a significant difference between the temperature of the measured sample and the ambient temperature, due to heat exchange between the sample and the surrounding environment, the temperature of the sample is unstable, and the surface temperature is not consistent with the center temperature. The temperature sensor located on the surface of the sample cannot accurately measure the true temperature of the sample, resulting in dynamic errors in temperature correction3.7.5.1The allowable error range,Users should try to avoid the above situation as much as possible.

3.8 insulation resistance

The insulation resistance between the power input terminal, the chassis grounding terminal, and the instrument measuring terminal should not be less than20MOh.

3.9 Power frequency withstand voltage

The power input terminal should withstand 45H between the chassis grounding terminal and the instrument measuring terminalz-65HzAt any frequency, the actual sine AC voltage is 1.5kVDuration 1minTest, no breakdown or arcing phenomenon.

4. Usage and Precautions

4.1 Introduction to Panel Functions

4.1.1 PC36Cpanel

picture1 PC36Cpanel

Among them（1）LCD display screen（2）Range selection switch

（3）Function selection switch（4）Power switch

（5）Zero calibration and balance knob（6）Reading hold switch

（7）Measure current forward and reverse selection switch

（8）Measurement status selection switch

（9）Current outputC1End (red)

（10）Voltage inputP1TheP2end

（11）Current outputC2End (black)

（12）Temperature input switch (step value:1℃）

（13）Temperature input switch (step value:0.1℃）

（14）温度校正（TC）Open or close（TC OFF）Select switch

Explanation: The range selection switch (2) has 12 gears but only 6 toggle positions. There are two scale lines on the knob pointing to different gears in the upper and lower halves. When the measurement state is selected as "normally"When measuring the current position, the "Nor" character appears on the display screen, and the top six gears (in blue font) are valid; When the measurement status selection switch is in the "low current" (low current high sensitivity) position, the "Low" character appears on the display screen, and the six gears in the lower half (black font) are valid. When converting the instrument range, the display screen shows the full range value (2, 20, 200, 2000) and resistance units (Ω, m Ω, μ Ω) for that gear.

4.2 Resistance measurement steps

4.2.1pressC1TheP1TheP2TheC2Connect the instruments and measuring fixtures in sequence (see figure)3），C1TheC2For the current end, connect it to the outside of the fixture;P1TheP2As the potential terminal, connected to the inside of the fixture, the red thick line isC1The fine line isP1The thick black line isC2The fine line isP2Due to the high measurement sensitivity of this instrument, when connectedP1TheP2At the end, it is advisable to avoid human contact as much as possible to prevent the heating of voltage nodes by the human body, which can cause thermocouple effects. The resulting thermoelectric potential will affect the measurement of small resistance.

4.2.2Instrument preheating and zero calibration: Turn on the function switch(3)Set to the 'zero calibration' position, the display screen will show“0.00Character, measurement status selection switch（8）Turn to the 'low current' position, range switch（2）Dial to200μ OmegaGear, the instrument is set to the highest sensitivity state at this time, turn on the power switch（4）Power on preheating3After minutes, adjust the zero and balance knobs（5）Make the instrument display value00.00. (Instrument internal zero calibration)

4.2.3Measure circuit potential balance: switch the function switch（3）Switch from 'Zero' to 'Balance' and the display screen will show“BALCharacters, numerical values may appear on the display screen, indicating the presence of unbalanced contact or thermoelectric potentials in the measurement circuit. Adjust the zero and balance knobs again（5）Make the instrument display value within0000and-0000Between them, it can counteract the influence of external potential. It should be noted that the unbalanced potential in the measurement circuit is often caused by the heating voltage node of the human body during the connection process. It is an unstable value that will slowly dissipate with temperature balance. If the reading on the display screen is large, the measurer should wait for a moment until the reading on the display screen drops to5a

Below the word, adjust the balance operation. Attention: After balancing operation, if you turn back to the "zero calibration" gear, the display screen will show "not working" again0The numerical value represents the potential imbalance inside and outside the instrument，After measuring the potential balance of the circuit, the zero calibration operation should not be repeated.If the instrument is in neutral gear, it can be reset to zero, but not in balance gear

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The phenomenon of being able to reset to zero and having a large range of reading changes is usually not a malfunction of the instrument but a failure to connect the measurement circuit. The possible reasons are: aThere is no sample placed on the fixture;b.The potential contact of the fixture is not effectively connected to the sample;c.Instrument'sP1TheP2The connection between the terminal and the fixture potential terminal is not connected, or the connecting wire is broken.

The essence of measuring circuit potential balance is to eliminate the influence of the measurement circuit thermoelectric potential on the measurement results, which is the same as the function of positive and negative current measurement. If it is determined to use positive and negative current measurement, users can directly skip the operation step of circuit potential balance.

4.2.4Resistance measurement: Turn the function switch to1.00I(Rated current measurement) gear, display screen appears“1.00IThe character and the numerical value displayed on the screen are the measured resistance values. If the display screen appears“1—To measure under range, the range switch should be turned on（2）Rotate clockwise until the instrument shows a reading; If the reading is less than1800One word, indicating that the measurement has exceeded the range, the range switch should be rotated counterclockwise to ensure that the measurement has high resolution.If the range is appropriate, the instrument reading should be within1800—19999Between (ignoring decimal points). The selection of measurement range should ensure that the measurement results have the most significant digitsExample: Using1Meter fixture measurement95mm²The copper conductor, in200μ Omega10AThe result of the range measurement is181.54μ Omega,while2000μ Omega10AThe result obtained from the measurement range is181.5μ Omega,at2mΩ1AThe result obtained from the measurement range is0.1815mΩAfterwards2In this situation, for4There is no valid reading for the first scenario5Position reading result181.54Mu Ω is more accurate.

According to the properties and resistance range of the tested device, select the appropriate measurement state and corresponding measurement gear. The instrument has six measurement ranges in the "conventional" measurement state (conventional measurement current), which has the characteristics of high measurement accuracy and good anti-interference performance. In the "low current" measurement state (low measurement current, high sensitivity), there are also six measurement rangesIt has high measurement sensitivity and resolution. The selection of measuring current must also comply withGB/T3048.4According to regulations, the current density of copper wires shall not exceed1A/mm², The current density of aluminum wire shall not exceed0.5A/mm².

with1mTaking fixtures as an example, the recommended measurement states, ranges, and current multiplier settings for common conductors are shown in the table5

table5

4.3 Reading retention:Keep the reading on/off switch（6）Dial to the 'hold' position, the display screen will show“HCharacters, instrument indication lock, convenient for users to record data. If continuous measurement is required, the reading hold switch should be placed in the 'measurement' position.

4.4Resistance measurement under reverse current:When measuring the DC resistance of wire and cable conductors, if the measured resistance is small

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Yu0.1ΩAccording to national standards, resistance measurement under reverse current should be carried out to further offset the influence of thermoelectric potential in the measurement circuit. Select the switch for measuring current in both forward and reverse directions（7）Dial toI-(Reverse current) position, display screen

A negative sign will appear before the resistance value, indicating that the value was measured under reverse current. The absolute value of this data should be compared withI+The data measured under forward current is added and divided by2As the final measurement result, compared with the measurement results under unidirectional current, this value has higher accuracy and reliability.

4.5 Resistance measurement under magnification current:Due to the large temperature coefficient between the tested copper wire and aluminum wire, if the wire is heated due to excessive current during the measurement process, it will cause serious measurement errors. According to national standards, a ratio of1：1.41The two measured currents are used to test the resistance values of the samples respectively, in order to determine whether there is an excessive temperature rise phenomenon. Turn on the function switch（3）Dial to1.41 I (1.41Double rated current)Gear position, display screen appears“1.41ICharacters, compare the obtained numerical value with1.00 IComparing the measurement results under rated current, if the change is less than the value specified in the standard, it indicates that1.00 IThe measurement results under certain conditions are valid, otherwise it indicates that the measurement current is too large, the data is invalid, and the measurement current must be reduced. You can turn the function switch to again0.707 I（0.707When the rated current is doubled, the display screen appears“0.707ICharacters, compare the obtained numerical value with1.00 IComparing the measurement results under rated current, if the change is less than the value specified in the standard, it indicates that0.707 IThe measurement results under certain conditions are valid, otherwise it indicates that the measured current is still too high and the range must be changed to reduce the rated current, or the measurement state selection switch must be placed in the "low current" position.

4.6 Temperature correction of copper and aluminum wires（PC36C）：

Temperature correction switch when measuring copper and aluminum wires(14)Place in 'Correction'（TC）Position, the display screen appears“TCThe 'character indicates entering the measurement mode with temperature correction, and then manually inputting the ambient temperature value, using the division value as0.1A mercury thermometer or other thermometer with a resolution of not less than ℃0.1A thermometer with a temperature of ℃ measures the ambient temperature, and thenInput the temperature into the switch（12）The （13）Set to ambient temperature, with switch（12）The setting range is15-26℃, with a step value of1℃. Switch（13）The setting range is0.0-1.1℃, with a step value of0.1℃The ambient temperature setting value should be the sum of the two, and the instrument indicates the value of the wire at the reference temperature20The resistance value at ℃ eliminates the trouble for users to convert according to the formula.

4.7Automatic temperature measurement and temperature correction(PC36E)：

4.7.1Connection and installation of temperature sensor

Insert the lead plug of the temperature sensor attached to the instrument into the sensor socket on the panel（15），AandBTwo sensors are placed and suspended on the left and right sides of the tested sample respectively (see figure)3）, distance60-70cmFor optimal results, the temperature at both ends of the sample can be sampled separately to eliminate errors caused by different temperatures at both ends of the sample.

Pay attention to keeping the sensor flat and not skewed. The center of the sensor must coincide with the center position of the tested sample. Nylon tape tightly adheres to the tested sample(See figure4)Installed with a micro platinum resistor surfaceIt must come into direct contact with the metal part of the sample, rather than being placed on the insulation skin.

Turn on the temperature correction switch(14)Place in 'Correction'（TC）Position, the display screen appears“TCCharacter, representing

The instrument enters temperature measurement and temperature calibration mode.

picture3 PC36EWiring diagram for measuring fixtures and installation diagram for temperature sensors

picture4 Temperature sensor structure

4.7.2Conductor resistance measurement with automatic temperature correction

Select the temperature coefficient switch of the instrument（16）Place the type of material being tested, such as soft copper wire, display screen

Soft copper wire will appear on the surfacealpha₂₀Numerical value“.00393'，At this point, the instrument indicates that the sample is at the reference temperature20The resistance value at ℃. Attention: If the material of the tested sample is set by this instrument5One of the commonly used materials (see3.7.3Section),instrumentIt is automatic temperature measurement and calibration, and there is no need to perform it separatelyMeasure the temperature of the conductor in this step.

4.7.3Conductor temperature measurement

Select the temperature coefficient switch of the instrument（16）Placed in the 'conductor temperature measurement' position, the display screen shows℃ symbol,The instrument reading is the temperature of the measured conductor, which isATheBThe average of the actual temperatures at the positions of two sensors. If the material of the tested sample is within the range set by this instrument5In addition to planting materials,Then it can be done throughAfter measuring the temperature of the conductor, convert it using a formula based on the temperature coefficient of the material.

4.8Measurement of coiled cables

4.8.1Measurement of coil resistance

Measure the resistance of the coiled cable,It is necessary to select the coiled cable testing pliers provided by our company, one in red and one in black,C1andP1Two red wires connected to red test pliers;C2andP2Two black wires connected to black test pliers, clamped at both ends of the coiled cable, ready for use4The method of line measurement is used to measure the resistance value of the disk.

4.8.2On semi-finished coiled cables1mMeasurement of conductor resistance

Semi finished coiled cables (without encapsulated insulation) must undergo1mThe common method for measuring conductor resistance to determine whether the cross-section is qualified is to cut it1Samples over a length of meters should be sent to the laboratory for several hours before testing. This method not only consumes labor and time, but also damages valuable non-ferrous metals. Taiou Electronics'PC36Ecan be0-40Accurate measurement of conductor resistance and temperature correction within the temperature range of ℃ can basically adapt to the environmental conditions of the production workshop, creating conditions for achieving lossless conductor resistance measurement. Although cable production workshops of domestic manufacturers generally do not have temperature control at present, and the temperature changes greatly throughout the four seasons, the temperature changes during day and night are not significant. The rate of temperature change under natural conditions is relatively slow, which is in line withPC36EThe requirement for the absolute value of temperature in environmental conditions is not high, as long as the temperature stability is good in a short period of time.

The semi-finished coiled cable must be cooled to the same temperature as the environment before measurement can be carried out. For the convenience of mobile operation, the diagram can be adjusted3The instrument shown and1Rice clamp, installed on a simple manual trolley. On site, avoid heat sources such as electric furnaces, infrared lamps, direct sunlight, and strong air convection such as blowers.

5 Precautions

5.1Requirements for the experimental environment

Due to the large temperature coefficient of the tested sample, small errors in the temperature measurement process often account for the majority of the overall error. Therefore, whether it is manual temperature measurement, manual input, or automatic temperature measurement and calibration, in order to ensure the accuracy of measurement and conversion, it is necessary to ensure the balance of environmental temperature. The instrument, tested sample, and fixture should avoid direct sunlight and direct air conditioning. The tested sample should be placed in this environment for a sufficient period of time to achieve sufficient heat dissipation

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Balance. In order to reduce the dynamic error of temperature correction, it is necessary to make every effort to minimize the fluctuation of environmental temperature

With precision temperature sensors and accurate temperature conversion coefficients（PC36E），The stability of environmental temperature has a greater impact on measurement results than the absolute value of environmental temperature.

Attention should be paid to the regular 'startup'-Stop type air conditioner, there is a transition between start and stop1-2℃The temperature difference can cause significant dynamic errors in temperature correction due to the significant difference in thermal inertia between the sensor of the temperature measuring instrument and the tested sample. The rapidly changing ambient temperature makes it difficult for the temperature sensor to accurately measure the true temperature of the sample,It is recommended to use central air conditioning or variable frequency air conditioning for temperature control in laboratories conducting conductor resistance tests.

When high accuracy is required for conductor resistance testing, it is recommended to use oil bath or water bath measuring fixtures (placing the wire and fixture in transformer oil or pure water), which can significantly reduce the impact of environmental temperature fluctuations on measurement, reduce the heating effect of measurement current on the wire, and improve the accuracy of temperature measurement and the stability of instrument readings.

5.2Scope of application of temperature correction function:

Special attention should be paid to:The temperature correction function is only effective when the material of the measured resistor is a specific material with a known temperature coefficient（PC36CFor pure copper and pure aluminumPC36Eprescribed5Common materials)，In addition, when the measured object is a standard resistance, contact resistance, or other physical resistance, and the material of the measured resistance is copper alloy, aluminum alloy, iron alloy, or copper or aluminum wire mixed with miscellaneous copper and aluminum, especially when the instrument is sent for inspection and verified with a standard, the temperature correction switch of the instrument is used（14）Must be placed in the 'off' positionAt this moment, the display screen appears

“TC OFFCharacters,The temperature correction function of the instrument is invalid. When entering the measurement mode of the conventional low resistance meter, the instrument

The displayed value is the actual resistance value of the measured resistor at the ambient temperature at that time. These temperature coefficients are different from the resistance measurements of specific materials. If the temperature correction coefficient of a specific material is mistakenly used, it will cause significant measurement errors, and the calibration of the instrument will also yield incorrect results.

5.3Other precautions

5.3.1This instrument is a specialized equipment for wire and cable conductor resistance testing, which adopts many new technologies and has some performance and characteristics that other digital low resistance meters do not have. In order to operate this instrument safely and correctly and ensure smooth measurement work,Users must carefully read this user manual before use,If you still have any questions, please feel free to call our company for consultation.

5.3.2When measuring the DC resistance of wire and cable conductors,The ambient temperature is within the national standard requirements15-25℃Within the scope, the instrument guarantees the3.3The measurement accuracy shown in the article. at0-40At an ambient temperature of ℃, the instrument can work normally, but the measurement accuracy is reduced by one level.

5.3.3 atC1TheC2TheP1TheP2Function switch when the end is suspended or there is no sample on the testing fixture（3）It must be placed in the 'zero calibration' position, and the function switch should also be placed in the 'zero calibration' position at the end of the measurement“Set the zero gear and disconnect the tested device. Do not open the load while measuring (remove the tested sample). Please also turn on the function switch when the instrument is not in use（3）Set to the 'School Zero' position.

5.3.4 PC36EThe accompanying pair of temperature sensors have undergone precise measurement, calibration, and pairing, and should be used accordingly

Handle with care. When installing and moving, grip the metal part of the sensor and do not drag its leads. Sensor nylon strap

A high-sensitivity micro platinum resistance surface temperature sensor is installed at the center position（2mm×2mmPay special attention to protection, especially the white part, to prevent collisions, scratches from hard objects, and avoid touching with hands to avoid dirt.

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5.3.5Measuring the conductor resistance of cables composed of multiple conductors, the quality of the measuring fixture has a great impact on the accuracy, stability, and repeatability of the measurement results, especially for large cross-section multi strand aluminum stranded wires. Due to the high contact resistance of the oxide film, the uneven distribution of conductor current brings great uncertainty to the measurement results. It is recommended to use a new type of hydraulic fixture, which can apply tons of pressure to the conductor, destroy the oxide layer on the surface of multiple strands of wire, and fully utilize the excellent performance of this instrument.

5.3.6When using the instrument, its ventilation holes should not be covered to ensure good heat dissipation. The testing site must avoid interference sources such as handheld drills, welding machines, high-power contactors, etc.

5.3.7When the instrument is not in use, it should be stored in a ventilated and dry environment to avoid extreme cold and high temperatures.

6 Execution standards and manufacturing assurance

6.1 The execution standard of this instrument is the Shanghai Enterprise StandardQ/AEXJ3.

6.2 Manufacturing guarantee: Users shall use or operate this instrument in accordance with the usage conditions specified in this user manual,From the date of purchase12Within one month, if the product is damaged or cannot function properly due to manufacturing defects, our company is responsible for providing free repair or replacement services to the customer. This instrument is subject to lifelong maintenance.

7 The completeness of the instrument set

Provide the following technical documents and attachments with each instrument:

Product Qualification Certificate 1User Manual1copy

power cord 1Root measuring wire1Pay

temperature sensor 1Pay (only)PC36E）