Some standard content:
National Metrology Verification Regulation of the People's Republic of China JJG105—2000
Tachometer
2000-05-08 Issued
2000-10-01 Implementation
Issued by the State Administration of Quality and Technical Supervision
JJG 105--2000
Verification Regulation
of Tachometer
JJG 105--2000
Replaces JJG105—1983
JJG 328—1983
JJG329—1983
JJG 327—1983
This regulation was approved by the State Administration of Quality and Technical Supervision on May 8, 2000 and came into force on October 1, 2000.
Responsible unit: National Technical Committee for Measurement of Vibration, Shock and Rotational Speed Drafting unit: Beijing Metrology and Testing Institute
China Institute of Metrology
This regulation is entrusted to the National Technical Committee for Measurement of Vibration, Shock and Rotational Speed for interpretation Main drafters of this regulation:
Wu Chengqi
Sun Peisheng
Participating drafters:
Wang Beilin
Xue Shuying
JJG105—20 00
(Beijing Metrology and Testing Institute)
(China National Institute of Metrology)
(Beijing Metrology and Testing Institute)
(Shanghai Automation Instrument Co., Ltd. Tachometer Factory) (China National Institute of Metrology)
Terms:
Technical requirements
Verification conditions and verification items.
Verification methods
Verification result processing and verification cycle,
JJG 105-2000
JJG 105—2000
Verification procedures for tachometers
This procedure applies to the verification of all types of tachometers that are newly manufactured, in use, and after repair. 1Terms
1.1 Tachometer
The instrument that measures the speed of various rotating objects is called a tachometer. 1.2 Revolution speed ratio: The ratio of the actual speed of the tachometer shaft to the tachometer scale value. A 1:1 tachometer may not indicate the speed ratio. 1.3 Intrinsic error of tachometer: The error of the tachometer under standard conditions. The basic error of the tachometer can be given in the form of reference error: Yuan = no×100%
Where: — basic error of tachometer, %;
n——the average value of the meter under test, r/min; no
nominal value of the calibration point, r/min;
N——a specific speed value (related to the calibration method), r/min. (1)
The basic error of the tachometer can also be given in the form of absolute error, called indication error, to facilitate the expression of the quantitative error of the digital meter:
An =n-ng
Where: An——speed indication error, r/min. 1.4 Indication variation of tachometer (2)
The maximum difference in the indication change when the same measured quantity is read repeatedly without any change to the measured object.
The variability of the tachometer indication can also be expressed in two forms with different symbols: 6 = nma + \ml × 100%
An, = nmax - nmin
Variability of indication, %;
Where: h
n max+ nmin
Variability of indication, r/min;
The maximum and minimum speed values in the same measurement, r/min1.5 Hysteresis error of tachometer (3)
G105—2000
Under the same conditions, when the measured value remains unchanged but the travel direction of the tachometer is different, the absolute tachometer return error of the difference between the values is given in the form of reference error: ve+
1.6 Swing ratio of tachometer When the speed decay is calibrated at the calibration point, the range of the tachometer pointer swing is the speed tends to be stable. The speed decay swing rate is given in the form of reference error: n×100%
Where: 3—swing rate, %;
nThe pointer swing value in the same measurement, /min. 1.7 Accuracy of time base frequency The deviation of the frequency value of the oscillator forming the time base from the nominal frequency, expressed by the following formula: A6
Where: A. Accuracy of time base frequency;
A. Average value of the frequency measured at the same time, H2; f. Standard frequency value, Hz
1.8 Stability of time base frequency (6)
The degree of change of the frequency of the oscillator forming the time base within a specified time, expressed by the following formula: The specified time should be indicated:
1.9 Reference standard In a given area or within a given organization, usually the measurement standard with the highest metrological characteristics, the measurements made there are derived from it.
In this regulation, the reference standard for speed calibration is called speed standard device: the standard frequency signal source is used for the calibration of the time base frequency accuracy and stability of the tachometer. 2
JJG105—2000
1.10 Reference conditions are the conditions for use specified for the performance test of the measuring instrument or for the comparison of the measurement results. Reference conditions generally include the reference value or reference range of the influence quantity acting on the measuring instrument. 1.11 Comparison
A set of operations to compare the values of the same kind of measurement reference, standard or working measuring instruments of the same accuracy level under specified conditions.
2 Overview
2.1 This regulation tests various types of average tachometers, that is, the average speed over a period of time. The symbol of the speed quantity is n: the name of the measurement unit is revolutions per minute, and the unit symbol is I/min. : 2.2 Tachometers are classified into fixed and handheld (portable); contact and non-contact; integrated and split types. They are mainly divided into 6 types according to the working principle.
2.2.1 Centrifugal tachometer: When the shaft of the tachometer rotates, the weight on the centrifuge leaves the axis under the action of inertial centrifugal force, and drives the pointer to rotate through the transmission system. When the spring reaction torque and the inertial centrifugal torque are balanced, the scale value shown after the pointer stops rotating is the measured speed value. 2.2.2 Timing tachometer: It is a method of measuring the number of revolutions of a rotating body within a certain time interval to determine the average speed, which is directly indicated on the dial by the pointer. Centrifugal and timing tachometers are usually called mechanical tachometers. 2.2.3 Magnetic induction tachometer: It is made according to the principle of magnetoelectric induction. The rotating magnetic field formed by the rotation of the permanent magnet on the tachometer shaft and the induced current of the sensitive element cutting the magnetic lines of force generate an interaction force. When the interaction torque of the two, i.e. the eddy current electromagnetic torque, is balanced with the reaction torque of the hairspring, the pointer on the tachometer dial indicates the measured speed value.
2.2.4 Electric tachometer: It uses a speed sensor (i.e. a tachometer generator) to connect with the measured rotating shaft and output a voltage signal, and the speed indicator indicates the measured speed value. Magnetic induction and electric tachometers are usually called magnetoelectric tachometers. 2.2.5 Stroboscopic tachometer: It is a tachometer made by using the visual persistence phenomenon of the human eye to measure the speed. 2.2.6 Electronic counting tachometer: It is a tachometer that uses a speed sensor to convert the mechanical rotation frequency into an electrical pulse signal, and counts and displays the corresponding speed value through an electronic counter. 3 Technical requirements
3.1 Appearance and structure of tachometer
3.1.1 The tachometer should be marked with the instrument name, model, indication range, measurement unit, accuracy level, speed ratio, manufacturer, factory number, production date and manufacturing license mark of measuring instruments. 3.1.2 The text symbols, signs, dial scale and scale values marked on the tachometer should be clear and correct. The tachometer shall not have defects that affect the reading.
3.1.3 The fasteners of the tachometer with pointer indication and dial switching should not be loose. The deflection of the pointer and the rotation of the dial should be smooth, without jumping or jamming during operation. The pointer and the dial should be able to return to zero or the specified position after operation. 3
JJG 105—2000
3.1.4 The starting and braking mechanism of the timing tachometer should be sensitive and reliable. In 10 consecutive starting tests, the interval between each two starting tests should not be less than 15s, and only one failure is allowed. For tachometers with a special return to zero button, the pointer should be able to return to the zero line by pressing the return to zero button. 3.1.5 The rotating shaft of the contact tachometer should be clean and free of oil stains, and its working status should be described in the manual. When turning by hand, it should feel good, without sticking, jamming, loose and tight phenomena, and there should be no faults that affect the reading during normal operation.
3.1.6 The digital display of the tachometer with digital display should be clear, accurate and function normally when working. 3.1.7 The working position of each conversion switch, step knob and regulator on the tachometer should be correct, flexible and reliable, and the corresponding measurement limit should be accurate.
3.2 Components of the tachometer
3.2.1 Speed sensor
3.2.1.1 When working according to the sensor installation requirements and usage methods indicated in the tachometer instruction manual, the sensor should be able to accurately transmit the electrical pulse signal corresponding to the speed. 3.2.1.2 The distance between the reflective head of the photoelectric sensor of the handheld tachometer and the measured rotating body should be no less than 8mm, and the roughness Ra of the measuring surface of the rotating body should be no less than 3.2μm. 3.2.1.3 The connection between the sensor and the electronic counter of the split tachometer should be reliable; the connecting wires, connectors and speed sensor accessories should be complete.
3.2.2 Probe and connectors of tachometer
3.2.2.1 If the tachometer uses a rubber probe or a pin-inserted probe, the probe should be clean, free of oil and defects, and maintain reliable contact without affecting the reading.
3.2.2.2 Connectors of tachometer
The plug-in and connection of each intermediate link of the tachometer should be tight and not loose, and the connection should be reliable. The connecting wires and connectors should be complete and intact. The pin-inserted connection should be compact and reliable, and no additional swing and abnormal jitter should be generated. 3.2.3 The strobe light equipped with a strobe tachometer should meet the following requirements: The strobe light intensity should be stable: The duration of the flash signal should make the single fixed image clear; The distance between the flash light and the rotating body to be measured should be not less than 200mm. 3.3 Working position and status of the tachometer
3.3.1 The manufacturer must explain the position and status of the tachometer for normal operation. ~-Generally, the dial of a handheld tachometer should be in a horizontal working position, and the dial of a fixed tachometer should be in a vertical working position.
3.3.2 The connection method of the tachometer connected by a flexible shaft or other speed transmission cable must keep the speed transmission process correct and the tachometer working state correct. 3.4 Tachometer Accuracy
3.4.1 The tachometer accuracy level is divided into 0.01, 0.02, 0.05, 0.1, 0.2, 0.25, 0.5, 1, 1.5, 2, 2.5.
3.4.2 The accuracy grade classification and various errors of centrifugal tachometers are shown in Table 1. 4
Accuracy grade
Basic error (%)
Indication variability (%)
Return error (%)
Amplitude ratio (%)
JJG 105—2000
Table! Centrifugal speedometer accuracy grade and required error 0.5
Note: Hand-held solid tachometers are not subject to operation error calibration: 1
3.4.3 The accuracy grade classification and various error requirements of timing speed are shown in Table 2, Table 2 The accuracy grade and various error requirements of timing speedmeter 3
The accuracy grade classification and various error requirements of magnetoelectric speedmeter are shown in Table 3, Table 3
Accuracy grade
Basic error %
System variability %
Return error %
Pointer swing rate %
Magnetoelectric tachometer accuracy grade and optional reading error 0.5
1 Hand-held magnetic induction tachometers are not subject to operation error calibration. 1.5
2 For the indicators of electrical instruments and the reduction of mechanical power, the error should not exceed 1.5 of the specified value. 5
JJG105—2000
3.4.5 The accuracy grades and error requirements of stroboscopic tachometers (dial readings) are shown in Table 4. Table 4 Accuracy grades and error requirements of stroboscopic tachometers (dial readings) Accuracy grade
Basic error %
Variability of indication %
3.4.6 The accuracy grades and error requirements of electronic counting tachometers and stroboscopic tachometers (digital display) are shown in Table 5.
Table 5 Accuracy grade and various errors of electronic counting tachometer and strobe tachometer [digital display) Accuracy grade
Allowable indication error
Allowable indication variability
Counter time base frequency
Accuracy better than
Counter time base 4 hours
Frequency stability better than
Significant figures ≥
±1 word
+2 words
5 × 10 -5
5×10-5
Note: n is the speed indication value,
±1 word
+2 words
1×10 4
1×10-4
±1 character
+2 characters
2.5×10-4
2.5 × 10 -4
±1 character
+2 characters
±1 character
+2 characters
±1 character
+2 characters
3.5. The accuracy grade classification and error requirements of other types of tachometers shall refer to the definition content and the provisions of Tables 1 to 5 of this Regulation.
4 Verification conditions and verification items
4.1 Verification environmental conditions
4.1.1 Room temperature (20±5)℃, relative humidity ≤85%. 6
JJG 105—2000
4.1.2: There should be no magnetic field or vibration in the laboratory that may affect the normal calibration of the tachometer: there should be no corrosive gas or liquid around. 4.1.3 The tachometer with a built-in stable power supply should be preheated as required. 4.2 See Table 6 for calibration items and calibration equipment. Table 6 Verification equipment and verification items
Verification equipment
Verification items
Appearance and accessories inspection
Basic error (indication error)
Indication variability
Return error
Swing amplitude
Time base frequency accuracy
Time base frequency stability
Speed standard device
Standard signal source or
Standard frequency meter
Technical requirements
The uncertainty of the standard device should be 2 to 3 times higher than the accuracy level of the tachometer being tested times
The uncertainty of the standard equipment should be 23 times higher than the accuracy level of the tachometer under test
Note: The finalization identification, initial calibration, subsequent calibration, and in-use calibration of the tachometer shall be carried out according to the items listed in Table 6. 5 Calibration method
5.1 Inspection of the appearance, structure and components of the tachometer 5.1.1 Inspection of the appearance and structure of the tachometer
All types of tachometers shall be inspected by visual inspection, manual inspection and power-on inspection. The inspection results must meet the requirements of the relevant provisions of 3.1 of this regulation.
5.1.2 Inspection of tachometer componentswwW.bzxz.Net
5.1.2.1 After inspection, the sensor of the tachometer shall meet the relevant requirements of 3.2.1 of this regulation. 5.1.2.2 After inspection, the probe of the tachometer shall meet the requirements of 3.2.2.1 of this regulation. 5.1.2.3 After inspection, the connector of the tachometer shall meet the requirements of 3.2.2.2 of this regulation. 5.1.2.4 The strobe light of the strobe tachometer shall meet the requirements of 3.2.3 of this regulation after inspection. 5.2 Inspection of the working position of the tachometer
5.2.1 Determine the working position of the tachometer in accordance with the requirements of 3.3.1 of this regulation and place it in the correct state. 5.2.2 For tachometers with flexible shafts to transmit speed, the flexible shafts or transmission cables must meet the requirements of 3.3.2 of this regulation. 7
JJG 105-2000
5.3 Calibration of handheld centrifugal and magnetoelectric tachometers 5.3.1 Test run inspection
5.3.1.1 Confirm that the contact between the rubber probe on the axis of the meter being inspected and the rotating shaft of the speed standard device is on the axis of the cylinder and there is no sliding.
5.3.1.2 The test run should be carried out three times at the middle value of the common measurement limit of the meter under test. When the tachometer shows no abnormal phenomenon, the indication verification can be carried out again.
5.3.2 Selection of verification points
Evenly select 5 verification points (including the lower limit and the upper limit) within the common measurement limit of the meter under test, and select 1 verification point for each of the remaining measurement limits. It is also possible to increase the verification points or conduct random inspections on the scales in question according to the user's requirements. 5.3.3 Verification of indication
Each verification point should be verified three times according to the following method. First adjust the speed standard device to the corresponding speed value, then slowly contact the rubber probe of the meter under test with the rotating shaft of the speed standard device. After the pointer tends to stabilize, read the swing amplitude of the pointer on the meter under test, and read the speed indication at the same time. Note: The indication value under test refers to the middle value of the pointer swing amplitude at a certain verification point. 5.3.4 Calculation of customer error
The basic error of the meter under test shall be calculated according to formula (1) of this regulation. The variability of the indicated value b of the meter under test shall be calculated according to formula (3) of this regulation. The swing rate β of the pointer of the meter under test shall be calculated according to formula (6) of this regulation. In the above formulas, N is the upper limit value of the corresponding measurement limit of the meter under test (r/min). 5.4 Verification of fixed centrifugal and magnetoelectric tachometers 5.4.1 Fixed centrifugal and magnetoelectric tachometers shall be installed on special fixtures for inspection. The connection between the sensor and the indicator of the electric or electric pulse tachometer shall be correct and reliable, and both shall be fixed and installed according to the working state. Confirm that the connection between the sensor shaft and the speed standard device shaft is on the same axis and there is no decoupling phenomenon. 5.4.2 When the rotation direction of the tachometer shaft is specified, the rotation direction of the shaft during verification shall be consistent with the specified rotation direction.
5.4.3 Test run inspection
Before the indication verification, the test run should be conducted for 1 minute at a position close to the upper limit of the tachometer's measuring range. The indication verification can be conducted only when the tachometer has no abnormal phenomena.
5.4.4 Selection of verification points
Select 5 verification points (including the lower limit and the upper limit) within the measuring range of the meter to be tested. Verification points can also be increased according to the user's requirements. For tachometers with double scales on the dial, the verification points should be selected on each scale according to the above method.
5.4.5 Verification of indication
Each verification point should be verified 3 times according to the following method. Turn on the speed scale push device, first increase the speed value steadily, reach each verification point one by one, and read the process speed indication of each verification point on the meter to be tested; then decrease the speed value steadily, return to each verification point one by one, and read the return speed indication of each verification point on the meter to be tested. Before each reading, observe the pointer swing value and calculate the swing rate according to formula (6) of this regulation. If the swing rate is within the range specified in Table 1 or Table 2, 8
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