6.3.6 Current transformer operation variation test
6.3.6.1 Ambient temperature influence
Place the test sample in an artificial climate chamber and place it at the upper and lower limits of the ambient temperature specified in the technical conditions for 24 hours respectively.
Measure the error of the tested transformer according to Article 6.3.4 of this regulation.
Compare this error with the error measured at room temperature (10℃~35℃), and take the one with the larger absolute value of the maximum error change in the upper and lower limit temperature tests as the measurement result of the temperature influence.
If the conditions are not met, the test can be carried out at the natural temperature in winter and summer. The test conducted at the installation site is allowed to be carried out according to the local extreme ambient temperature.
6.3.6.2 Residual magnetism influence
During the test, a DC current equivalent to 10%~15% of the rated secondary current is passed through the secondary winding of the tested current transformer for magnetization.
The duration is not less than 2s. Then measure the error according to Article 6.3.4. Compare this error with the error measured in the demagnetized state, and take the absolute value of the error change as the measurement result of the residual magnetism influence.
6.3.6.3 Influence of adjacent primary conductors
During the test, place adjacent primary conductors according to the manufacturer's technical requirements.
Then perform the error test according to 6.3.4.
Compare this error with the error measured without adjacent primary conductors (or far away), and take the absolute value of the error change as the measurement result of the influence of adjacent primary conductors.
When the test conditions are not met, the influence can be estimated by theoretical calculation.
6.3.6.4 Influence of high-voltage leakage current
During the test, the secondary of the current transformer is connected to the rated load, and the S, terminal is grounded.
The primary side applies the test voltage according to the rated voltage factor specified in GB 1208.
6.3.6.5 Influence of equal ampere-turn method
During the test, change the primary conductor connection according to the technical requirements to change the current ratio, and then perform the error test according to 6.3.4.2.
Take the absolute value of the maximum deviation measured in various test connections as the measurement result of the influence of equal ampere-turn method.
6.3.6.6 Influence of working connection
During the test, connect the primary circuit bus according to the technical requirements and pass the current and voltage equivalent to normal operation.
Then, perform the error test according to 6.3.4.2.
It is allowed to apply current and voltage separately, and then add the influence quantities according to the algebraic sum.
Compare the deviation of the error of the tested transformer under working connection and the error under laboratory conditions, and take the absolute value as the measurement result of the working connection influence.
6.3.7 Voltage transformer operation variation test
6.3.7.1 Ambient temperature influence
Refer to 6.3.6.1.
6.3.7.2 Combined transformer primary conductor magnetic field influence
During the test, the tested voltage transformer is connected to the rated secondary load, and the primary side is connected according to the operating state.
Load the primary bus current to the rated value according to the manufacturer's technical conditions, and then measure the secondary voltage of the tested voltage transformer.
6.3.7.3 External electric field influence of capacitive voltage transformer
The tested capacitive voltage transformer is tested under laboratory conditions and installation conditions respectively.
Calculate the deviation of the test results under the two environments, and take its absolute value as the measurement result of the external electric field influence.
