5.1 Verification conditions
[JJG313-2010] 5.1.1 Environmental conditions
5.1.1.1 Ambient temperature 10℃~35℃, relative humidity not more than 80%.
[JJG314-2010] 5.1.1 Environmental conditions
5.1.1.1 Ambient temperature 10℃~35℃, relative humidity not more than 80%.
[Article interpretation] The reference ambient temperature of the basic error specified in Chapter 3 Metrological Performance Requirements is 0℃~40℃, while the ambient temperature required for verification here is 10℃~35℃, which are not the same; because when considering the environmental conditions for verification, in addition to ensuring that the measured instrument can be used normally and has no additional errors, it is also necessary to consider that the verification device can work normally under this environmental condition and ensure its accuracy.
Therefore, the reference environmental conditions for the basic error do not necessarily need to be the same as the environmental conditions required for verification, and should be determined according to the verification standard device and the laboratory's requirements for verification error.
In addition to standard current and voltage transformers and current and voltage ratio standard devices, the transformer calibration standard devices also include transformer testers and transformer load boxes.
Standard transformers and ratio standards are actually manufactured according to the standards of instrument transformers, so the temperature and humidity ranges required by the transformers being tested are the same.
In addition, JG169-2010 stipulates that the temperature reference conditions for the basic error of the transformer tester are 0℃~40℃, and JJF1264-2010 "Transformer Load Box Calibration Specification" stipulates that the error of the transformer load box at the reference temperature of 20℃+5℃ shall not exceed +3%, and the additional error shall not exceed +2% for every 10℃ change. Based on this, it is believed that the error within the temperature range of 10℃~35℃ shall not exceed ±5%, and the impact on the transformer calibration can be controlled within 1/10 of the basic error limit.
The above analysis shows that the calibration standard device can ensure the required accuracy within the temperature range of 10℃~35℃.
The relative humidity conditions of the environment required for verification are consistent with the relative humidity conditions of the reference environment for basic error.
[JJG313-2010] 5.1.1.2 The measurement error introduced by the electromagnetic interference generated by the equipment used for verification, such as boosters, voltage regulators, etc., during operation shall not exceed 1/10 of the error limit of the current transformer under test.
[JJG314-2010] 5.1.1.2 The measurement error introduced by the electromagnetic interference generated by the equipment used for verification, such as boosters, voltage regulators, etc. during operation shall not exceed 1/10 of the error limit of the voltage transformer under test.
[JJG313-2010] 5.1.1.3 The measurement error caused by the external electromagnetic field shall not exceed 1/20 of the error limit of the current transformer under test.
[JJG314-2010] 5.1.1.3 The measurement error caused by the external electromagnetic field shall not exceed 1/20 of the error limit of the voltage transformer under test.
【JJG313-2010】5.1.2 Power supply and regulating equipment The power supply and regulating equipment should have sufficient capacity and fineness of regulation.
The frequency of the power supply should be 50Hz±0.5Hz (60Hz±0.6Hz), and the waveform distortion coefficient should not exceed 5%.
Note: When calibrating current transformers of level 0.01 and above, pay attention to the influence of the waveform distortion of the power supply and the neutral line voltage of the power supply on the measurement results.
When the measured indication is unstable or abnormal, consider using a higher quality power supply.
【JJG314-2010】5.1.2 Power supply and regulating equipment
The power supply and regulating equipment should have sufficient capacity and fineness of regulation.
The frequency of the power supply should be 50Hz±0.5Hz (60Hz±0.6Hz), and the waveform distortion coefficient should not exceed 5%.
Note: When calibrating voltage transformers of level 0.01 and above, pay attention to the influence of the waveform distortion of the power supply and the neutral line voltage of the power supply to the ground on the measurement results.
When the measurement indication is found to be unstable or abnormal, consider using a higher quality power supply.
