The main purpose of the transformer calibrator is to verify the technical performance of voltage transformers and current transformers used in the field or in the laboratory. To achieve this goal, the transformer calibrator must form a complete transformer calibration device together with related equipment. Since there is a close technical correlation between the performance indicators of the transformer calibrator and the related equipment, in order to correctly study and understand the overall concept of the transformer calibrator, it is necessary to have a basic understanding of the transformer calibration device.
Transformer calibrators in China can be roughly divided into three generations: the first generation of electrical calibrators is cumbersome to operate and has complex wiring; the second generation of calibrators adopts more advanced electronic circuits, which is more convenient to use than the previous generation, but requires manual switching of range gears during measurement and displays limited information during testing. Most of the third generation calibrators use microcontrollers, which improves the intelligence of the instrument. Some instruments have computer communication interfaces, enhancing the level of office automation.
Here we mainly introduce the main features of the third generation transformer calibrator:
(1) It uses a microcontroller to implement functions such as measurement, control, and display;
(2) It has a computer interface to improve office automation and reduce manual labor intensity;
(3) It has a large screen display, providing a friendly user interface and rich measurement information;
(4) It can automatically perform transformer measurement and automatically switch the current and voltage load boxes;
(5) It has good protection measures and can promptly inform users of error information;
The instrument can achieve class 2. Currently, most calibrators on the market use the resistance-capacitance phase-shifting 90° method for data measurement. This method is susceptible to environmental temperature and power frequency. Once the above environment changes, the measurement data will be greatly affected.
The YTC2168 transformer calibrator adopts a unique circuit principle and DSP technology to avoid the above problems.
From the perspective of measurement principles, transformer calibrators can also be divided into two categories: direct comparison type and difference measurement type.
Early transformer calibrators were mainly designed based on the direct comparison principle, that is, the secondary voltage or current of the standard transformer and the tested transformer are respectively sent to the transformer calibrator. Through measuring circuits such as resistive voltage dividers, resistance-capacitance voltage dividers, and magnetic potential comparators, the difference voltage or difference current between the two is obtained. After processing, it becomes the ratio error and phase error of the tested voltage transformer or current transformer relative to the standard transformer.
