Some standard content:
National Metrology Verification Regulation of the People's Republic of China JJG874--2007
Temperature Indication Controller
Temperature Indication Controller2007-02-28Promulgated
Implementation on 2007-08-28
The General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China issued JJG874—2007
Verification Regulation of
Temperature Indication ControllerJJG874—2007
Replaces JJG874—1994
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on February 28, 2007, and came into effect on August 28, 2007.
Responsible unit: National Technical Committee on Temperature Metrology Main drafting unit: Tianjin Metrology Technology Research Institute Participating drafting units: Changzhou Metrology Technology Research Institute Italy Olonqiang (China/Hong Kong) Representative Office Testo Instruments International Trading (Shanghai) Co., Ltd. Xuzhou Elite Electric Technology Co., Ltd.
This regulation is entrusted to the National Technical Committee on Temperature Metrology to be responsible for the interpretation of this regulation Main drafters:
JJG874—2007
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Wang Chaoying (Tianjin Metrology Technology Research Institute) Liu Wei (Tianjin Metrology Technology Institute) Tian Yun (Tianjin Institute of Metrology) Participating drafters:
Li Junwei (Changzhou Institute of Metrology) 6819796
Home and Country Education
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Wu Fengrong (Italy Olonqiang (China/Hong Kong) Representative Office) Chen Jun (Testo Instruments International Trading (Shanghai) Co., Ltd.) Li Chaofei (Xuzhou Elite Electrical Technology Co., Ltd.) National Preparation National Group Single National Store
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Foreign Center Tong Ying Steel International University
Company Public China (Xinhua) 4.1 Indication error
Stability
Set point error
4.4 Switching difference
5 General technical requirements
Appearance
Insulation resistance
5.3 Insulation strength
6 Control of measuring instruments
6.1 Verification conditions
6.2 Verification items
6.3 Verification method
Processing of verification results | |tt||6.5, Verification cycle·
JJG874—2007
Appendix A Verification record format for temperature indicating controllers
1 Scope
J.JG874-2007
Verification procedure for temperature indicating controllers
This procedure applies to the initial verification, subsequent verification and in-use inspection of pointer-type and digital temperature indicators, temperature indicating controllers and temperature controllers (hereinafter referred to as temperature controllers) with a measurement range of (-50～+300)℃ and using temperature measuring thermistors or other semiconductor temperature measuring sensors. 2 Terminology
2.1 Thermistor
A temperature sensing element used for temperature measurement made of polycrystalline semiconductor materials whose resistance value changes exponentially with temperature. 2.2 Error of setpoint The difference between the measured temperature value and the temperature value corresponding to the set point when the output variable is output according to the specified requirements. 2.3 Cut-off value
The temperature value measured when the output changes from one state to another in the upper stroke (or lower stroke) of the temperature controller. 2.4 Cut-off difference The difference between the upper and lower stroke cut-off values.
2.5 Scale interval
The difference between the two values of two adjacent scale marks. 2.6 Graduation line
The line segment used to scale the scale mark within the limit indication limit 2.7 Main scale mark
The line segment with scale mark and rest value within the limit indication limit. Its line segment is thicker than the general scale line. Overview
The temperature controller is generally composed of temperature measurement indication and control parts together or separately. The temperature measurement part is based on the characteristics of the temperature sensor changing with temperature. After being processed by the corresponding circuit (including application of operational amplifier, microprocessor, etc.), the instrument indicates the corresponding temperature. The temperature control part is generally composed of a setting circuit, a corresponding signal processing circuit and a comparison circuit, and a position control execution circuit.
Sensor
Measurement circuit
Setting circuit
Signal processing circuit
Comparison circuit
Principle block diagram of temperature indicating controller
Instrument indication circuit
Control execution circuit
4 Measurement performance requirements
4.1 Indication error
JJG874—2007
Outing Baojin Energy Indicator
4.1.1 The allowable temperature error value is expressed as: y=±N
Where: N—allowable temperature error value, °C. 4.1.1.1 The indication error of the pointer temperature controller shall be in accordance with the provisions of Table 1. Measuring range/C
Indication allowable error/
Digital temperature control
Measuring range/℃
Indication allowable error/℃
Switching difference/℃
SOE ONS
Table 1 Indication error of pointer-type temperature controller
00-300
Maximum error
Temperature controller
Indication allowable error and switching difference
20~200
For any temperature controller whose measuring range is not listed in the table, the indication allowable error and switching difference shall be subject to the production
.
4.2 Stability
Digital temperature control
4.3 Set point errorbzxZ.net
The fluctuation of the indication value of the instrument shall not be allowed to jump in the interval counting sequence. The setting error of the temperature controller should not exceed the indication error 4.4 Switching error 20--300 0~-300 The specification gives the indicator The switching error of the pointer temperature controller should not be greater than 1/2 of the absolute value of the allowable error when the upper limit temperature is ≤100℃. When the upper limit temperature is greater than 4, it should not be greater than the absolute value of the indication error. The switching error of the digital temperature controller shall be implemented according to the provisions of Table 2. The temperature controller with adjustable switching error shall meet the requirements of the switching error adjustment range.
5 General Technical Requirements
5.1 Appearance
5.1.1 The nameplate of the temperature controller shall be marked with the product name, model, measurement range, company name, factory number, manufacturing year and month, and the symbol "℃" representing the international temperature scale Celsius. 5.1.2 The packaging material used for the temperature controller measurement sensor should be free of cracks. The lead connector must have good contact. The protective tube and packaging material used for the temperature sensor should be able to withstand the corresponding operating temperature. 5.1.3 The exposed parts of the temperature controller (terminals, panels, switches, etc.) should not be loose or damaged; the digital indicator panel should not have defects that affect the reading. Each switch and knob should have the corresponding function and a certain adjustment range when in the specified state.
JJG874—2007
The starting point adjuster of the indicating instrument of the pointer temperature controller should be able to be adjusted to the starting point of the pointer normally, and the pointer of the indicating instrument should move smoothly without needle jamming, jitter and hysteresis. 5.1.5 The pointer of the pointer-type temperature controller should be within 1/4 to 3/4 of the shortest scale line. The width of the pointer tip shall not be greater than the width of the main scale line and shall be perpendicular to the scale line. 5.1.6 The display value of the temperature controller shall be clear. The digital display of the digital temperature controller shall have no overlapping characters and the brightness shall be evenly checked. There shall be no phenomenon of dimming or missing strokes. The decimal point and the symbols indicating the positive and negative temperature states and the overload state shall be displayed correctly. 5.1.7 The setting knob mark of the temperature controller shall be able to be set on any scale line of the scale and coincide with it. ENOH NIISTE
5.2 Insulation resistance
At ambient temperature (15~
The insulation resistance shall meet the requirements of Table 3
Power supply terminal and housing
Input terminal and housing
Terminal and power supply terminal
Output terminal and housing
Terminal and output terminal
5.3 Insulation strength
When the test voltage with a fixed frequency of 50 is applied at an ambient temperature of
(15~35), there should be no alarm phenomenon
When the relative humidity is <80%0, the insulation resistance between the terminals of the temperature controller is
Insulation resistance technical requirements
When the humidity is 80%RH, the insulation resistance between the terminals of the temperature controller is
The insulation resistance between the terminals of the temperature controller is
The insulation resistance between the terminals of the temperature controller is
The insulation resistance between the terminals of the temperature controller is
The insulation resistance between the terminals of the temperature controller is
Specification
Duration min
Breakdown and leakage current are set at 5mA Dielectric strength test voltage
Instrument terminal voltage 2 nominal value/V
OKU6OCHINA
60≤U<130
130≤U<250
Measuring instrument control
Measuring instrument control includes initial verification, subsequent verification and in-use inspection. 6.1 Verification conditions
6.1.1 Verification equipment
Test voltage/V
6.1.1.1 Standard instrument: a set of (-60300)C second-class standard mercury thermometers or other standards with an accuracy level not lower than that of second-class standard mercury thermometers. 6.1.1.2 Constant temperature bath: technical performance see Table 5. JJG874—2007
Table 5 Technical requirements for constant temperature bath
Alcohol low temperature bath
Reading device.
Ice point meter.
Using temperature
Range/℃
60~Room temperature
Room temperature-95
95~300
500V, 10-level insulation resistance meter
Maximum
Temperature difference in working area/C
Horizontal
Temperature difference in working area/℃
Temperature control fluctuation
/C·(10min)--
The output voltage is not less than 1500V, the output power is not less than 0.25kW, and the withstand voltage tester has leakage current setting.
6.1.2 Environmental conditions
6.1.2.1 Calibration environment temperature: (15～35)℃: humidity <80%RH. 6.1.2.2 The environmental conditions for the use of standard instruments and electrical measuring equipment should comply with their corresponding regulations. 6.1.3 Power supply conditions
The power supply voltage change shall not exceed 1% of the rated voltage, and the power supply frequency change shall not exceed 1% of the rated frequency. 6.2 Verification items
The verification items are shown in Table 6.
Table 6 Verification items
Verification items
Indication error
Set point error
Switching difference
Stability
Insulation resistance
Insulation strength
First verification
Note: "+" indicates the items to be checked, and "_" indicates the items that may not be checked. 6.3 Verification method
6.3.1 Appearance inspection
Observe the temperature controller visually, which shall comply with the provisions of 5.1. 6.3.2 Preheating and adjustment after power-on
Subsequent verification
In-use inspection
JJG874—2007
After the power is turned on, preheat according to the time specified by the manufacturer. If there is no clear specification, generally preheat for 15 minutes, and then conduct verification. For instruments with external "zero adjustment" and "full adjustment", pre-adjustment is allowed after preheating, but no further adjustment is allowed during the verification process.
6.3.3 Verification of indication error
6.3.3.1 Verification points: For the first verification of the temperature controller, the verification points for the pointer-type temperature controller shall be evenly distributed on the main scale line of the entire measuring range, and for the digital temperature controller, they shall be evenly distributed on the temperature points of ten or hundred (including the upper and lower limits of measurement), and shall not be less than 5 verification points (calibration points can also be added according to user requirements, but the verification points should be selected on the main scale line or on the temperature points of ten or hundred). 6.3.3.2 For subsequent verification or in-use inspection of the temperature controller, the verification points for the pointer-type temperature controller shall be evenly distributed on the main scale line of the entire measuring range, and for the digital temperature controller, they shall be evenly distributed on the temperature points of ten or hundred (including the upper and lower limits), and shall not be less than 3 verification points (calibration points can also be added according to user requirements, but the verification points should be selected on the main scale line scale or on the temperature points of ten or hundred). 6.3.3.3 Verification sequence: first calibrate the zero point, then calibrate point by point towards the upper or lower limit. 6.3.3.4 Reading method: for pointer-type temperature controllers, read the reading perpendicular to the dial scale line to 1/10 of the minimum scale value. When reading with a magnifying glass, the line of sight should pass through the center of the magnifying glass. For digital temperature controllers, read directly, and the number of readings should not be less than two (for digital temperature controllers with unstable last digit display, the reading can be increased to four times and the average value is taken).
6.3.3.50℃ point verification: insert the temperature sensor of the temperature controller into an alcohol low-temperature tank or an ice point device containing an ice-water mixture. When using an ice point device, the working end should not be less than 20mm from the bottom and wall of the ice point device. Read after the indicated value stabilizes.
6.3.3.6 Verification of other temperature points: the comparison method is used during verification. Insert the temperature sensor of the temperature controller into a constant temperature tank and compare it with the indicated value of the standard thermometer. After the indication is stable, read the value. During the reading process, the temperature of the thermostat bath shall not deviate from the temperature of the calibration point by more than ±0.20℃. (Based on the standard thermometer) The temperature change of the bath shall meet the temperature control fluctuation requirements in Table 5. Read from the standard, read to the object to be tested, and then read from the object to the standard. 6.3.3.7 The actual temperature and indication error are calculated according to formula (2) and formula (3) respectively: T=A+X
Where: T—actual temperature of the thermostat bath, ℃; A—indication of the standard thermometer, ℃;
X—correction value on the certificate of the standard thermometer for the calibration point, ℃y=tT
Where: y—indication error of the temperature controller at the point to be tested, ℃; t——indication of the temperature controller at the point to be tested, ℃.
6.3.4 Verification of set point error and switching difference (2)
6.3.4.1 Selection of set point: When the temperature controller is first verified, the set point should be set on the main scale line near 30%, 50%, 80% of the entire measurement range or at the temperature point of ten or hundred. 6.3.4.2 When the temperature controller is subsequently verified or inspected during use, the verification point should be set on any main scale line or at the temperature point of ten or hundred within the entire measurement range (except the upper and lower limits of the measurement). Verification points can also be added according to user requirements, but the added verification points should also be selected on the main scale line or at the temperature point of ten or hundred. 5
JJG874—2007
6.3.4.3 Verification method: It should be carried out simultaneously with the indication verification of the temperature controller. Align the setting knob of the temperature controller to the scale line corresponding to the temperature point to be calibrated. Use the setting knob of the digital temperature controller with digital setting to adjust it to the set point value. Insert the temperature sensor of the temperature controller and the standard thermometer into the constant temperature bath at the same time, and then slowly increase the temperature of the constant temperature bath. When the switching indicator changes or when the output state of the temperature controller changes, read the indication of the standard thermometer. The indication is the upper switching value. Then slowly reduce the temperature of the constant temperature bath. Similarly, when the switching indicator changes or when the output state of the temperature controller changes, read the indication of the standard thermometer again. The indication is the lower switching value. During calibration, the bath temperature rise and fall speed should not exceed 0.1℃C/min. Use the same method to operate again. 6.3.4.4 The set point error is calculated according to formula (4): yset = (A + Adown)/2 - Aset
Where: yset -
Set point error, °C;
The average value of the switching point indication on the standard thermometer, C: The average value of the switching point indication on the standard thermometer, C: The set point temperature, °C.
6.3.4.5 The switching difference is calculated according to formula (5): Where: ycut -
Switching difference, °C.
6.3.5 Stability verification
cut = [A-AT]
The stability verification of digital temperature controller is carried out at the same time as the verification of indication error. During the verification, the temperature point can be selected at any point within the temperature measurement range of the temperature controller, and then the temperature is slowly raised to observe whether the display of the temperature controller being tested jumps and displays continuously in sequence. 6.3.6 Insulation resistance
The temperature controller is in the power-off state, and the power switch is in the on position. Use an insulation resistance meter with a voltage of 500V to test the parts specified in Table 3. During the test, the given 500V DC voltage should be maintained for 10s before reading. 6.3.7 Insulation strength
The temperature controller is in the power-off state, and the power switch is in the on position. Use a withstand voltage tester to test the parts specified in Table 3. During the test, the test AC voltage gradually and steadily rises from zero to the voltage value corresponding to Table 4 within (5~10)s. The leakage current is set at 5mA and lasts for 1min. There is no breakdown, arcing phenomenon or leakage current alarm. Then it drops steadily to zero and the power is cut off. The temperature controller should work normally after the test. 6.4 Handling of verification results
A verification certificate shall be issued for qualified temperature controllers according to the requirements of this regulation, and a verification result notice shall be issued for unqualified temperature controllers, with the unqualified items indicated.
6.5 Verification cycle
The verification cycle of a temperature controller shall be determined according to the specific use conditions and use time, and shall generally not exceed 1 year. 6
Appendix A
Inspection unit:
Manufacturer:
Appearance:
Name of standard instrument:
Validity period of standard instrument:
Ambient temperature:
Difference/℃
Humidity:
JJG874—2007
Verification record format of temperature indicating controller
Model:
Factory number:
Measuring range:
Graduation value:
Certificate number:
Stability:
Standard instrument number:
Uncertainty of standard device:||t t||Filling difference:
%RH:Verification basis: JIG874-2007 "Verification Procedure for Temperature Indicating Controllers"Verification point
Indication of standard instrument
Average value of standard instrument
Indication of temperature controller to be inspected
Average value of inspected
Actual temperature
Indication error
Actual temperature=standard indication+correction value
Indication error=inspected value-actual temperature
Verification point
Upper switching value
Upper switching average value (A)
Lower switching value
Lower switching average value (A)
Set point Error/C
Switching difference/℃
Insulation resistance
Insulation strength
Verifier:
Verifier:
y segment=（AE+A）/2-A segment
Sweep=A up-A down
Verification conclusion:
People's Republic of China
National Metrology Verification Procedure
Temperature Indicating Controller
JJG874--2007
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Published by China Metrology Press
No. 2, West Street, Hepingli, Beijing
Postal Code 100013||tt| |Tel: (010) 64275360
http://zgjl.com.cn
Beijing Dixin Printing Co., Ltd.
Published by Beijing Publishing House of Xinhua Bookstore
All rights reserved. No reproduction allowed
16-mo
880mmX1230mm
First edition in April 2007
Printing sheet 0.75
Word count 10,000 words
First printing in April 2007
Print run 1-2000
Uniform book number 155026-2240
Price: RMB 16.00
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