【JJG313-2010】5.3.6.3 Current, load and power factor used in error measurement
During periodic calibration, the error measurement of current transformers shall be carried out according to the conditions listed in it.
The secondary load can be set to the rated value or the actual value.
The secondary load of newly manufactured and repaired current transformers is specified as the rated value.
When calibrating a large number of newly manufactured current transformers of the same model, the error measurement points can be reduced on the premise of confirming that they meet the requirements of this regulation after supervision and random inspection by the metrology agency or relevant competent authorities.
In addition to the first calibration, users are allowed to apply for calibration of only part of the power factor according to their actual use, but uncalibrated power factors are not allowed to be used in work.
【JJG 314-2010】5:3.5.2 Voltage, load and power factor used in error measurement
During periodic calibration, the error measurement of voltage transformers shall be carried out according to the conditions listed in Table 3. The secondary load can be set to the rated value or the actual value.
The secondary load of newly manufactured and repaired voltage transformers is specified as the rated value.
For voltage transformers used under special conditions, error tests shall be conducted according to the actual voltage percentage, secondary load and power factor conditions.
When calibrating a large number of newly manufactured voltage transformers of the same model, after supervision and random inspection by the metrology agency or the competent department, the error measurement points can be reduced on the premise of confirming that they meet the requirements of this regulation.
【Article Interpretation】If there are no special requirements, the errors of current transformers and voltage transformers are measured under the conditions that the secondary load is the rated value and the lower limit value and the power factor is equal to it.
For current transformers and voltage transformers with other load requirements, the errors shall be measured under the specified load.
【JJG313-2010】5.3.6.4 For current transformers with multiple current ratios, all current ratios shall be calibrated.
Bus type current transformers can only calibrate one current ratio at each rated ampere-turn.
For busbar current transformers with a rated primary current greater than 2.5kA, the equal ampere-turn method is allowed to be used for verification when the primary conductor magnetic field does not affect its error more than 1/10 of its error limit; if the primary conductor magnetic field does not affect its error more than 1/6 of its error limit, and the actual error of the standard does not exceed 1/10 of the error limit of the current transformer being tested, the equal ampere-turn method can also be used for verification.
During verification, the position deviation of the primary conductor from the center axis should not be greater than 1/10 of the through-hole diameter; the distance between the primary return conductor and the winding shall not be less than the maximum geometric size of the transformer.
If the primary conductor is a symmetrically distributed split busbar, the distance requirement can be reduced in proportion to the number of split roots.
