Correction method for instrument voltage transformer

Abstract

The invention discloses a correction method for an instrument voltage transformer, and comprises the steps of: firstly combining at least two inductive voltage dividers in a primary-secondary cascade connection, and configurating the transformation ratio tap positions of a primary inductive voltage divider and a secondary inductive voltage divider to enable the transformation ratio after the primary-secondary cascade connection combination to be the same as that of a certain tap position of the instrument voltage transformer; then obtaining errors of the primary inductive voltage divider and the secondary inductive voltage divider by self-correcting and verifying; and finally calibrating the self-corrected and verified primary inductive voltage divider and secondary inductive voltage divider to be a voltage ratio criterion, and comparatively transmitting the voltage ration criterion to the instrument voltage transformer to realize the correction of the change of a certain tap position of the instrument voltage transformer. The correction method for the instrument voltage transformer can improve the correction accuracy of voltage / voltage conversion under the condition of a low-voltage output of the instrument voltage transformer.

Description

technical field [0001] The invention relates to a calibration method of a standard device, in particular to a calibration method of an instrument voltage transformer. Background technique [0002] The function of the instrument voltage transformer is to transform the high voltage into a low standard secondary voltage in proportion to the use of protection, metering and instrumentation devices. Due to the needs of electronic measurement in the fields of industry, military, metrology, scientific research and other fields, the technology of precision instruments and meters has developed rapidly, and new technical requirements for instrument voltage transformers have emerged: [0003] 1) The output voltage is below 10V, such as the secondary rated output of the electronic voltage transformer used in the digital substation of the smart grid is 4V. [0004] 2) The accuracy of conversion from input to output is required to reach the ppm level, such as the 50-100-200-400V / 4V voltag...

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Problems solved by technology

[0038] (3) Manual operation is required for micro-difference compensation, and the verification time is long;

[0039] (4) When verifying the existing stereotyped products such as the FG2 induction voltage divider whose design accuracy is converted to 1ppm input, the output rated voltage is designed to be 100V, and the working voltage of the matching calibrator is also 100V, and this standard is used for comparison When the instrument uses a voltage transformer, it cannot operate at full voltage;

[0040] (5) In order to meet different voltage ratio requirements, the FG2 induction voltage divider is a multi-disc induction voltage divider formed by cascading multiple single-disc induction voltage dividers. When the voltage ratio of the compared instrument voltage transformer is less than 10 : 1 (the voltage transformation ratio of the general instrument voltage transformer is less than 10:1, such as the 100V / 4V segmental equipotential shielding induction voltage divider with an accuracy of 1ppm, and the 50-100-200- 400V / 4V instrument dual-stage voltage transformer), the first disc of the FG2 inductive voltage divider will have no output, but if the FG2 inductive voltage divider is to ensure 1ppm ratio accuracy, the output of the first disc cannot be 0, that is, , when the first disk has no output, its accuracy will be greatly reduced, and the error of the induction voltage divider converted from the voltage transformer used for precision instruments to the input has reached 4×10 -8 , It is difficult to find a higher standard that satisfies the relative inspection by using the relative inspection method; (relative inspection method: the relative error is obtained by comparing the calibrated equipment with the standard equipment) because the "National Metrology Verification Regulations (JJG244-2003)" stipulates: used for traceability The accuracy of the standard equipment should be an order of magnitude higher than that of the equipment being calibrated. At this time, the influence of the error of the standard equipment can be ignored. Therefore, the FG2 inductive voltage divider in the traditional method can only be used as a comparison reference in the calibration of voltage transformers for precision instruments. It cannot be used as a traceability standard, that is, it cannot be used to calibrate instrument voltage transformers

[0041] In summary, due to the above defects, the existing high-precision instrument voltage transformers cannot meet the above new technical requirements: 1) The output voltage is low voltage, that is, the transformation ratio is lower than 10:1; 2) The transformation accuracy is high

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