Some standard content:
Trial Verification Regulation for DC Digital Voltmeters
JJG315—1983
Trial Verification Regulation for True Current Digital Voltmeters
Yerification Regulation t I
Digital Weltmeter
JJG315—1963
This verification regulation was approved by the national metrology department on April 19, 1983, and was implemented on March 1, 1984. The responsible unit is: China Metrology Research Institute
Original unit: China Metrology Research Institute The main drafter of this regulation:
Feng Tuling [China Metrology Research Institute] Participating drafters:
Su Desheng [China Metrology Research Institute] Zhang Chundi (China Metrology Research Institute) E Jiaye (China Metrology Research Institute)
Reference requirements and verification conditions
Error correction methods
Other items Purpose Verification and test
Verification scope and processing of verification results
Complete the verification of the main technical documents...
Record 2 DC digital voltmeter verification system·Purpose
Appendix 3 DC digital voltmeter verification record format Appendix 4 Other technical specifications Special tests
Trial verification procedures for DC digital voltmeters
Introduction
This procedure is applicable to the verification of DC digital voltmeters (XDVM) produced and processed, and the DC voltage measurement part of digital multimeters. This procedure is also applicable to certain measuring instruments that convert real current into voltage for digital scientific research, as well as analog/digital converters (AT converters) related to these instruments. The calibration of L-LVM
With the rapid development of digital technology and the widespread use of high-performance digital instrument (LDVM), it has been gradually involved. LDVM is the most basic part of DVM and digital instrument. In view of this situation, it is necessary to first unify the calibration method of L-LVM, and gradually consider the rationality of both manufacturing and convenience, which is the basic starting point for the formulation of this regulation. 2. Technical requirements and calibration conditions for calibration
" Calibration overview
TC-DVM is a high-precision instrument. In order to use it correctly and ensure the accuracy of the measurement results, various L-LVMs must be calibrated. The calibration work is divided into the following 3 situations: 1.1 Synchronous calibration
This is a routine calibration of general precision instruments. One is under standard conditions. The periodic verification contents under the condition of the equipment should include: basic error, superposition error, load tolerance, resolution, display capability, input terminal resistance, zero current and other technical indicators such as analog interference suppression ratio. The DCDVM of periodic verification should be rated in advance. 1.2 Repair diagnosis
After the damaged VM is repaired, in order to ensure the reliability of the equipment, it should be checked again according to the items of periodic verification. It is also called according to the repair situation, or add some important verification contents. 1.3 Acceptance inspection
It is the inspection work of the new instrument (including imported 1VM) connected. It has more requirements than periodic verification, such as temperature coefficient, influence of power supply change, insulation resistance, withstand voltage test, measurement speed, response time, signal quality and other technical indicators. "Verification", type adjustment and other items specified in the acceptance verification can be carried out in parallel. 2. Appearance and electrical inspection
In order to determine whether the instrument can operate normally, the instrument itself shall be inspected externally and powered on before verification. 2.1 Appearance inspection
2.1.1 The appearance and structure are intact, and the indicator panel, reading structure, manufacturer, instrument number, model, etc. should be clearly marked.
2.1.2 The instrument has no loose parts or mechanical damage, etc.: whether the instrument parts, auxiliary lines, power supply, and grounding terminals are complete; whether switches, knobs, etc. are turned correctly; 2.1.3 The power supply voltage and frequency of the instrument, the fuse of the power supply fuse meet the requirements, and replacement shall not be hindered. In particular, the input AC 220V or E10V power supply should be connected correctly and the ground should be connected correctly. 2.2 Electrical inspection
Check the appearance of the product, and make sure that the power is on for the test. 2.2.1 All switches and knobs must be in the correct position, and the input signal types (DC voltage, AC voltage, resistance, current) must correspond to the measuring function. 2.2.2 Power on and run the preheating according to the manual, and check the electrical performance. 2.2.3 Check whether the "voltage", "frequency value", "positive and negative calibration" and other function cards are working normally. 2.2.4 According to the measurement range and measurement range of the meter under test, input appropriate DC voltage signals in sequence, check the manual, range switching and instrument operation are normal. Change the signal, and observe whether the readings are discontinuous, whether there are overlaps, or not charging.
2 .2.5 Change the input signal to check whether it can be done 1, and the display is 2.2.6 Before the sampling mode is checked
, check whether manual, automatic, and continuous reading timing sampling can be performed. The interception table should be placed in the constant overflow case 241, and then the main technical indicators are calibrated. 3 Principles for selecting calibration points
3.1 The basic measurement is a measure of the performance of an L-LVM. The calibration should be carefully selected, and generally the whole range is required.
3.2 Considering the sensitivity of DVM, the basic measurement points should be selected evenly. 3.3 The range coverage should be considered, that is, the continuity of the measurement error of each range should be guaranteed, and there should be no discontinuity points in the middle of each range. 3.4 According to the different working principles of TDC-DVM, the principles for selecting calibration points should also be somewhat different. 3.5 Other Other non-basic ranges should consider the upper and lower limits and the corresponding calibration points of the maximum error of the basic range. According to the above requirements, less than 10 calibration points are collected in the basic range, and 3 to 5 calibration points are taken in the non-basic range.
3.6 The voltage drop of the positive and negative polarities is measured in a group of pairs. According to the above principles, the number of test points is selected, and the calibration work can be carried out. 4 Requirements for standard devices and other equipment
4.1 The comprehensive error of the entire standard device system should be less than 1/3-1.5 of the allowable error of the TX-DVM under test. 4.2 The stability and stability of the voltage of the first current signal source should be less than 1/5~1 of the allowable error of the VM under test. The signal source should be continuously adjustable or adjusted by external adjustment equipment. The signal source has a low internal resistance, and the AC ripple and peak noise in the output DC voltage are as small as possible, and do not cause additional errors such as DCDVM. 4.3 The standard instruments and residual equipment used should be measured regularly and qualified. 4.4 When the error of the standard resistance is less than 1/5 of the allowable error of the sensitive test LX-TVM, it can be ignored. When it is greater than 1/5 of the allowable error of the whole powder 1XDVM, it cannot be ignored. At this time, the following principles should be followed: If the error of the meter is 10% and the error of the standard is -\%, the verification error result should be kept within 2 (1)%.
When the standard with an error of ± m% is used for verification, if the error of the verification result exceeds ± e%, but is kept within (e-)%, it cannot be used as a basis for return. 4.5 The entire measuring circuit system should have good parallelization and grounding facilities to avoid single-mode and common-mode interference, and should be away from electromagnetic fields and magnetic fields to avoid electromagnetic field induction, electrostatic induction, etc. 5. Regarding standard conditions and rated working cases, according to the provisions of Safety 11X:485, combined with the specific conditions of my country, it is required that the basic error of DC.DVM be determined, calibrated and used according to the standard provisions specified in the table.
In order to determine the rated working conditions, the instrument is divided into A, 1, (one group: Group A is in a good ring spray 241
Long typical quantity
Ring difference
Phase source seat ()
Large and small reflective
(mnHg)bzxz.net
Sunlight exposure
Pressure due to air flow rate
Study gas dust volume
Air ten has
Air reduced water
Working position quantity
External electric field external electric connection
True son Tao radiation
Alternation power supply voltage
Power supply sea
Shape head true (2)
Change potential positive
( Direct speed electric number)
Patrol electric voltage
Elements [Rebuilding the word voltage conditioning city to determine the standard working conditions and rated working recording parts standard parts
No direct change
Cannot be detected
Cannot be said
Manufacturer department public
Not available
Left and right
Cannot be said
Rated voltage
Cannot be brushed
Mountain manufacturer regulations
By manufacturing "determined
1nH=3.32Ps(version * cow)
Purchase and
Set table dynamic material
+ 5...+
20- 8G
(No strict
607-·E00
Yuanzhi rule purchase
Neck fixed T. Dyeing parts
to-·30
(No）
+60 · 90C
25 - 1 55
no extreme shock,
460-·9C6
sun pre-radiation plus the ring group
suffering time group individual effect is not fast grid
for only the shadow of the table enjoy the name slightly ignored
by the wide range more determined
improved by the annual effect of the annual environment temperature deficiency for
55 hours, and the skin
in the system standard "" said
out system into the factory protection After adjustment, the factory stipulates that the influence of the environment is not likely to be affected. The internal material is set to determine the reference test. Due to the obstruction of ventilation, the upper environmental temperature is 3. The temperature should not exceed the temperature under the simple condition of environmental obstruction (+15%) T:
Continuous workpiece time
Standard bar
Basic section positioning heart is used
Working to do
:32-ib
The instrument is only used in the table; Group B is used in general environment; Group C is used in harsh environment. The rated working error of TVM is determined, calibrated and used according to the specified working conditions. The reading error of DC-DVM is accurate
6.1 Basic error
The basic error formula of DVM is expressed in one of the following forms. 6.1.1
The absolute error expressed by the sum of the two errors is: 4 =+(a% +%[m)
Value of the meter under test (displayed value);
Full scale value of the meter under test:
Error coefficient related to the reading value;
Error coefficient related to the full scale value,
6.t.1 is expressed as the relative difference compared to the IVM reading value: a% -t%
6.2 Accuracy level
Based on the principle of LCM, the external characteristics of the DC voltage meter are unique to electrical measurement. The accuracy of DC:DVM is divided into: D.0005, 0.001, D.002, 0.005, 0.1, .02, .05, 0.1, .2, 0.5 and 1.0. There are 11 levels in total (ton meter 2) 2 True digital voltage level
Annual rated error
(D,=, phase difference)
>2-10cn
>10040
>s00Mn
（1020
≤100
≤ [2~5) ×10 \A
:2--5) k10-\A
S: X PA
:x10 A
x10 *A
1 × In-tA
] x 10 A
DCLVM is a multi-disc instrument, different quantities have different accuracy. General requirements:
(.0005 level, L.001 level, 0.rX02 level, 6-digit display
0.05 level, 0.01 level, should have 5-digit display: 0.02 level, 0.05 level. Should have 4-inch digital display; 0.1 level, should have 3 The digital display is displayed immediately.
Chapter 3.3 Grade Standard
The accuracy grade is mainly determined by the size of the DVM basic measurement error coefficient (!) and the annual stable error. At the same time, the size of the auxiliary resistance and zero current of the required range should be appropriately considered. The grading criteria are as follows: 1.3.1 Under standard conditions, the calibration data after preheating, pre-adjustment and calibration meet the basic error of the meter under test. 1.3.2 Regular periodic inspections are required: The graded 1JVM is required to be tested under standard conditions for a period of time without calibration, and its annual stable error is tested. This error should meet the requirements of (2%, +6%U.): At the same time, the annual change of the value of the meter under test is less than or equal to (%. +%) Where, & is the annual assumed error coefficient of the basic range of the meter under test (if the meter under test If there is no error indicator for one year, the metrology department can determine the accuracy of the meter under test according to the actual test results or the error indicator for half a year! ,
6.3.3 After the annual error is verified, the 24h basic error shall be verified again. This number shall meet the basic error indicator.
G.3.4 The resistance and zero current of the meter under test shall meet the indicators listed in Table 2. The meter under test shall be graded after the above regulations. The certificate of the last inspection shall be available for grading. The first inspection shall not be graded.
After grading, the DC-DVM used by the equipment can be pre-adjusted, but calibration is not allowed. The new microprocessor digital meter (PDVM) is generally passed according to the conventional verification items and determined according to the above standards.
The calibration method of three error corrections There are many error verification methods and standards for 71XIM, but in principle they can be summarized into one: DC standard voltage generator method; direct comparison method (standard digital meter method); DC standard instrument method. Depending on which method is adopted, the most appropriate, economical, and simple method can be selected according to the standard equipment available and the level of the meter being tested. Some of the verification methods for this type of instrument are given below. 7.1 DC standard voltage generator method: This method is shown in Figure 1 (a). Assume that the DC standard voltage generator is U and the actual value is U. The displayed reading of the TWVM being tested is , and the error of the meter being tested is =tt
The corresponding error of the meter is expressed in fractions. =Ue100%
When the range of the polarity DVM is much smaller than the maximum display range of the standard voltage generator or the ranges of the two do not match, a 444
voltage divider can be used. After the voltage divider, it is connected to the test table, as shown in Figure 1 (b). The relative error of the test table is expressed as a fraction: Li,
The voltage divider coefficient of the standard voltage divider.
This method must take into account the influence of the input resistance and power supply of the test table, and select a low voltage divider. This method is convenient and fast, and is suitable for large-scale factory testing of DVM
When the accuracy of the standard voltage source cannot meet the requirements, but the stability is relatively high, the standard source can be used as a light voltage stabilizer, equipped with a standard LVM, and the TVM can be tested by comparison.
.2 Direct comparison method (standard digital old method) The circuit diagram of the direct comparison method is shown in Figure 2 ().
Generally speaking, the number of digits of the standard DVM should be one more than that of the tester VM. In this method, it is necessary to ensure that the standard M is always accurate. For this reason, the standard meter must be regularly calibrated and calibrated.
Standard current meter
Voltage meter#
Standard voltage meter
Standard voltage meter method
When the adjustable voltage power supply box outputs a voltage, the display reading of the standard meter is, the error of the meter under test is, the relative error of the meter under test is expressed in fractions:
,-Ux10%
If the standard meter does not meet the range of the meter under test, or sometimes the standard meter only meets the accuracy requirement for a certain range, the range can be expanded by using standard voltage dividers, as shown in Figure 2 (b), (c). By the same token, we can get:
Or:
DC standard instrument method
KUN100%
This method is to use the DC standard instrument and the DVM under test to measure the same voltage, and use the actual reading value of the DC standard instrument to find the indication value of the meter under test. The DC standard instrument is essentially a true current standard voltage measuring device. There are many types and forms of calibration circuits, but the basic principle is the same. It uses a true current standard voltage ratio standard battery to derive a series of standard voltages. The more typical ones are as follows: 3.1 Potentiometer method
This method is shown in Figure 3.
The DVM can be directly calibrated with a potentiometer. When the range selection is in progress and the DVM is at the basic range, the power consumption is very high. At this time, the potentiometer can be used as a DC standard power source. From its non-powered end (i.e., the output standard voltage signal is converted into IVM. Figure 3 = FN is the standard battery and C is the current detector. IVM calibration with direct comparison method is widely used in production accuracy. 7.3.3 Difference method When the potentiometer inputs a standard voltage (using the common gear dial method), the display of the meter being tested reads L! The relative error of the meter being tested is expressed as a percentage:-n00%
Use the potentiometer to directly determine the basic range of the DVM. The potential barrier 1 of the upper limit of the filter can be satisfied
7.3.1 Calibration of the potentiometer and the voltage divider box [VM] The above calibration circuit is a convenient method when there is no appropriate DC signal source and voltage regulator. When the DVM is tested with a high potential source, it must be equipped with a voltage divider and a voltage source to perform the calibration, as shown in Figure 4.
When the adjustable voltage source outputs a voltage, the value measured by the potential difference meter is L, and the displayed reading of the meter under test is 1, then the relative error of the meter under test is expressed as a percentage: 5-100%
This method is relatively complicated, but the device is accurate, stable and reliable, so it is used in standard measurement. The method is to verify the accuracy of the DVM. When the potential difference meter requires high accuracy, there is no high accuracy potential difference. You can use a multi-speed voltage transformer to measure the difference value, as shown in Figure 5. E is the electromotive force value of the standard battery. You can select one or more standard batteries in series according to the size of the measured voltage to make the difference voltage equal to L, and then use the potential difference to measure the value. This measurement requires a high quality differential meter. It is best to use a low-potential differential meter. Then there is: Can you hear the touch? Use the voltage transformer to determine the DVM. UN= A(E-AU) If the display value of the meter under test is: The relative error of the meter under test is expressed by the white value: -us100%=E. - K(E=AL) ,
mode can be used. In this calibration method, the accuracy of the calibration is guaranteed. The main diagram of the electromotive force and the voltage division coefficient K is shown in Figure 7.3.4. When the DVM is calibrated into a voltage divider box, a multi-speed divider box can be used. The principle can also be used as a potential difference. As shown in Figure 6, the standard battery and the multi-speed divider are matched. First, the positive voltage is made equal to the electromotive force E of the standard battery. The voltage is used as the power supply, but the voltage is small. The difference method is used to determine the position of the galvanometer G, which is fast and has the benefit of the resistance R. Then turn switch K to "2", the voltage divider box will start to output the standard voltage. The difference between VM display value and the voltage divider box display value is the error of M. One way is to use standard voltage to measure 2. If the voltage at two points is accurate and stable, the multi-decade voltage divider box can continuously output the standard voltage and reach the drop period of TIVM, which is equivalent to a standard voltage source. 8 Stability error verification
IXIM's stability error should be carried out in one range. The verification method is the same as the method for determining the difference between LC-LTVM and LC-LTVM. You can choose any one of them. The long-term stability of the signal source is required to be high, otherwise the change of the signal source and the drift of LI\/M cannot be distinguished.
[X-DVM wire is preheated and pre-filled, the input end is shorted, and the probe signal is input without adjusting the instrument. Then the voltage change of each test point is observed.
According to the regulations and requirements of the manual,
can measure the stability error within a specified time period, but the DVM for graded verification must be tested for short-term stability error of 24h and long-term stability error of 1 year. The number of measurements of the DVM should not be less than 3. The short-term stability error formula index of the main record value is used to judge whether the DVM is qualified.
9 Determination of linear error
The linear error is an important index to measure the DVM, which can be combined with the basic error determination. This index is generally only tested within the basic range. The TVM error verification method is basically applicable to the linear error verification. IV Verification and testing of other items
10 The test of the display capability
can be carried out together with the power-on test (generally measuring the basic range). The power source supplies a DC signal, and now the meter under test can be tested. Take the 20000 sequence as an example: 0.0001
.0009—0.0.01.50
It can also be carried out according to the following rules.
0.OC0+.H1
0.00oy-0.00
0.0999 .*0.1030
0.9999 1.0000
.12·...000N—0.000
.019[02.K84.09[
0.199,2[0]-..-·.8999 41.5001.9999 -'2.0000
The drum point can work smoothly and change smoothly, and its display ability is good. Whether it is caused by a problem or not, it is also necessary to check the tribute, negative pole (especially pay attention to whether the positive and zero positions appear alternately), small effective point and load display ability. 11 Resolution method
Generally, the highest resolution of the lookup table is measured only at the minimum range. It can be tested with a high-resolution measuring device. For example, the signal source supplies a DC signal to make the measured WVM display value a certain value, and read the indicated value of the measuring device at the same time: then fine-tune the measured LVM to change the value by one digit, and then read the indicated value of the measuring device. The difference between the two measured values is the resolution of the measured table. 12 Input voltage and zero current test
Put the test DVM into working state, change the voltage: the ratio of the auxiliary voltage change U at the LVM input terminal to the input current change △ is the test resistance under working state, expressed by scale:. According to this definition, the function can be connected as follows:
When K1, K2 are in the normal position, read the different indications of the whole test IVM respectively: K1 is set to 1, K2 is set to 3, the indication value is 1A, K2 is set to 1, K2 is set to 4, the indication value is [UK, at 2, K at 3, the indication value is [
K, set to 2, K2 is set to 4 Appendix: The indication value is [J24. According to the above reading, the input resistance and quarter current of the meter under test can be calculated according to the following formula: Input resistance
R1 =AU?AI
AU- - [14
Al-Uar i UuPu
Ja-L4-U/R, R is 105.-10)
Zero current can also be tested with a micrometer, as shown in Figure 8, which uses the galvanometer method to test the current difference. Connect the galvanometer G to the input end of VM, and the zero current is: is - aGtR +r)/R
Where is the number of deflection grids of the galvanometer;
The internal resistance of the galvanometer:
C is the sensitivity constant of the galvanometer.When the voltage divider is calibrated, the multi-speed divider can also be used as a potential difference. As shown in Figure 6, the standard battery and the multi-speed divider are matched. First, the positive voltage is used to make the voltage divider's indication equal to the electromotive force E of the standard battery. The resistor R is used as the power supply, so the difference method is used to determine the position of the voltage divider. The current meter G points to zero. Then the switch K is turned to "2", and the divider starts to output the standard voltage. The difference between the VM display value and the divider's indication value is the error of M. One way is to use the standard voltage to measure the voltage. The voltage at the two points is accurate and keeps stable. The multi-decade voltage divider can continuously output the standard voltage and reach the drop period of TIVM. This is equivalent to a standard voltage source. 8 Stability error verification
IXIM's stability error should be carried out in all ranges. The verification method is the same as the LC-LTVM error verification method. You can choose any one. The long-term stability of the signal source is required to be high, otherwise the change of the signal source and the drift of LI\/M cannot be distinguished.
[X-DVM wire preheating, pre-full, short-circuit the input end, and input the probe signal without adjusting the instrument, and then observe the voltage change of each test point.
According to the regulations and requirements of the manual,
can measure the stability error within a specified time period, but the DVM for graded verification must be tested for short-term stability error of 24h and long-term stability error of 1 year. The number of measurements of the DVM should not be less than 3. The short-term stability error formula index of the main record value is used to judge whether the DVM is qualified.
9 Determination of linear error
The linear error is an important index to measure the DVM, which can be combined with the basic error determination. This index is generally only tested within the basic range. The TVM error verification method is basically applicable to the linear error verification. IV Verification and testing of other items
10 The test of the display capability
can be carried out together with the power-on test (generally measuring the basic range). The power source supplies a DC signal, and now the meter under test can be tested. Take the 20000 sequence as an example: 0.0001
.0009—0.0.01.50
It can also be carried out according to the following rules.
0.OC0+.H1
0.00oy-0.00
0.0999 .*0.1030
0.9999 1.0000
.12·...000N—0.000
.019[02.K84.09[
0.199,2[0]-..-·.8999 41.5001.9999 -'2.0000
The drum point can work smoothly and change smoothly, and its display ability is good. Whether it is caused by a problem or not, it is also necessary to check the tribute, negative pole (especially pay attention to whether the positive and zero positions appear alternately), small effective point and load display ability. 11 Resolution method
Generally, the highest resolution of the lookup table is measured only at the minimum range. It can be tested with a high-resolution measuring device. For example, the signal source supplies a DC signal to make the measured WVM display value a certain value, and read the indicated value of the measuring device at the same time: then fine-tune the measured LVM to change the value by one digit, and then read the indicated value of the measuring device. The difference between the two measured values is the resolution of the measured table. 12 Input voltage and zero current test
Put the test DVM into working state, change the voltage: the ratio of the auxiliary voltage change U at the LVM input terminal to the input current change △ is the test resistance under working state, expressed by scale:. According to this definition, the function can be connected as follows:
When K1, K2 are in the normal position, read the different indications of the whole test IVM respectively: K1 is set to 1, K2 is set to 3, the indication value is 1A, K2 is set to 1, K2 is set to 4, the indication value is [UK, at 2, K at 3, the indication value is [
K, set to 2, K2 is set to 4 Appendix: The indication value is [J24. According to the above reading, the input resistance and quarter current of the meter under test can be calculated according to the following formula: Input resistance
R1 =AU?AI
AU- - [14
Al-Uar i UuPu
Ja-L4-U/R, R is 105.-10)
Zero current can also be tested with a micrometer, as shown in Figure 8, which uses the galvanometer method to test the current difference. Connect the galvanometer G to the input end of VM, and the zero current is: is - aGtR +r)/R
Where is the number of deflection grids of the galvanometer;
The internal resistance of the galvanometer:
C is the sensitivity constant of the galvanometer.When the voltage divider is calibrated, the multi-speed divider can also be used as a potential difference. As shown in Figure 6, the standard battery and the multi-speed divider are matched. First, the positive voltage is used to make the voltage divider's indication equal to the electromotive force E of the standard battery. The resistor R is used as the power supply, so the difference method is used to determine the position of the voltage divider. The current meter G points to zero. Then the switch K is turned to "2", and the divider starts to output the standard voltage. The difference between the VM display value and the divider's indication value is the error of M. One way is to use the standard voltage to measure the voltage. The voltage at the two points is accurate and keeps stable. The multi-decade voltage divider can continuously output the standard voltage and reach the drop period of TIVM. This is equivalent to a standard voltage source. 8 Stability error verification
IXIM's stability error should be carried out in all ranges. The verification method is the same as the LC-LTVM error verification method. You can choose any one. The long-term stability of the signal source is required to be high, otherwise the change of the signal source and the drift of LI\/M cannot be distinguished.
[X-DVM wire preheating, pre-full, short-circuit the input end, and input the probe signal without adjusting the instrument, and then observe the voltage change of each test point.
According to the regulations and requirements of the manual,
can measure the stability error within a specified time period, but the DVM for graded verification must be tested for short-term stability error of 24h and long-term stability error of 1 year. The number of measurements of the DVM should not be less than 3. The short-term stability error formula index of the main record value is used to judge whether the DVM is qualified.
9 Determination of linear error
The linear error is an important index to measure the DVM, which can be combined with the basic error determination. This index is generally only tested within the basic range. The TVM error verification method is basically applicable to the linear error verification. IV Verification and testing of other items
10 The test of the display capability
can be carried out together with the power-on test (generally measuring the basic range). The power source supplies a DC signal, and now the meter under test can be tested. Take the 20000 sequence as an example: 0.0001
.0009—0.0.01.50
It can also be carried out according to the following rules.
0.OC0+.H1
0.00oy-0.00
0.0999 .*0.1030
0.9999 1.0000
.12·...000N—0.000
.019[02.K84.09[
0.199,2[0]-..-·.8999 41.5001.9999 -'2.0000
The drum point can work smoothly and change smoothly, and its display ability is good. Whether it is caused by a problem or not, it is also necessary to check the tribute, negative pole (especially pay attention to whether the positive and zero positions appear alternately), small effective point and load display ability. 11 Resolution method
Generally, the highest resolution of the lookup table is measured only at the minimum range. It can be tested with a high-resolution measuring device. For example, the signal source supplies a DC signal to make the measured WVM display value a certain value, and read the indicated value of the measuring device at the same time: then fine-tune the measured LVM to change the value by one digit, and then read the indicated value of the measuring device. The difference between the two measured values is the resolution of the measured table. 12 Input voltage and zero voltage test
Put the test DVM into working state, change the voltage: the ratio of the auxiliary voltage change U at the LVM input terminal to the input current change △ is the test resistance under working state, expressed by scale. According to this definition, the function can be connected as follows:
When K1, K2 are in the normal position, read the different indications of the whole test IVM respectively: K1 is set to 1, K2 is set to 3, the indication value is 1A, K2 is set to 1, K2 is set to 4, the indication value is [UK, at 2, K at 3, the indication value is [
K, set to 2, K2 is set to 4 Appendix: The indication value is [J24. According to the above reading, the input resistance and quarter current of the meter under test can be calculated according to the following formula: Input resistance
R1 =AU?AI
AU- - [14
Al-Uar i UuPu
Ja-L4-U/R, R is 105.-10)
Zero current can also be tested with a micrometer, as shown in Figure 8, which uses the galvanometer method to test the current difference. Connect the galvanometer G to the input end of VM, and the zero current is: is - aGtR +r)/R
Where is the number of deflection grids of the galvanometer;
The internal resistance of the galvanometer:
C is the sensitivity constant of the galvanometer.0000
If the voltage can work smoothly and change smoothly, its display ability is good. Otherwise, there is a problem. In addition, the voltage and negative poles should be checked (especially pay attention to whether the positive and zero positions appear alternately), the minimum effective point and the load display ability should be checked. 11 Resolution mode
Generally, the highest resolution of the lookup table is only measured at the minimum range. It can be tested with a high-resolution measuring device. For example, the signal source supplies a DC signal to make the displayed value of the WVM under test a certain value, and read the indicated value of the measuring device at the same time: then fine-tune the LVM under test to change the value by one digit in the last position, and then read the indicated value of the measuring device. The difference between the two measured values is the resolution of the table under test. 12 Input voltage and zero current test
Put the test DVM into working state, change the voltage: the ratio of the auxiliary voltage change U at the LVM input terminal to the input current change △ is the test resistance under working state, expressed by scale:. According to this definition, the function can be connected as follows:
When K1, K2 are in the normal position, read the different indications of the whole test IVM respectively: K1 is set to 1, K2 is set to 3, the indication value is 1A, K2 is set to 1, K2 is set to 4, the indication value is [UK, at 2, K at 3, the indication value is [
K, set to 2, K2 is set to 4 Appendix: The indication value is [J24. According to the above reading, the input resistance and quarter current of the meter under test can be calculated according to the following formula: Input resistance
R1 =AU?AI
AU- - [14
Al-Uar i UuPu
Ja-L4-U/R, R is 105.-10)
Zero current can also be tested with a micrometer, as shown in Figure 8, which uses the galvanometer method to test the current difference. Connect the galvanometer G to the input end of VM, and the zero current is: is - aGtR +r)/R
Where is the number of deflection grids of the galvanometer;
The internal resistance of the galvanometer:
C is the sensitivity constant of the galvanometer.0000
If the voltage can work smoothly and change smoothly, its display ability is good. Otherwise, there is a problem. In addition, the voltage and negative poles should be checked (especially pay attention to whether the positive and zero positions appear alternately), the minimum effective point and the load display ability should be checked. 11 Resolution mode
Generally, the highest resolution of the lookup table is only measured at the minimum range. It can be tested with a high-resolution measuring device. For example, the signal source supplies a DC signal to make the displayed value of the WVM under test a certain value, and read the indicated value of the measuring device at the same time: then fine-tune the LVM under test to change the value by one digit in the last position, and then read the indicated value of the measuring device. The difference between the two measured values is the resolution of the table under test. 12 Input voltage and zero current test
Put the test DVM into working state, change the voltage: the ratio of the auxiliary voltage change U at the LVM input terminal to the input current change △ is the test resistance under working state, expressed by scale:. According to this definition, the function can be connected as follows:
When K1, K2 are in the normal position, read the different indications of the whole test IVM respectively: K1 is set to 1, K2 is set to 3, the indication value is 1A, K2 is set to 1, K2 is set to 4, the indication value is [UK, at 2, K at 3, the indication value is [
K, set to 2, K2 is set to 4 Appendix: The indication value is [J24. According to the above reading, the input resistance and quarter current of the meter under test can be calculated according to the following formula: Input resistance
R1 =AU?AI
AU- - [14
Al-Uar i UuPu
Ja-L4-U/R, R is 105.-10)
Zero current can also be tested with a micrometer, as shown in Figure 8, which uses the galvanometer method to test the current difference. Connect the galvanometer G to the input end of VM, and the zero current is: is - aGtR +r)/R
Where is the number of deflection grids of the galvanometer;
The internal resistance of the galvanometer:
C is the sensitivity constant of the galvanometer.
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