The current transformer calibrator is a special instrument used for verifying current transformers. Traditional current transformer calibrators mostly adopt the difference principle to take the difference, and then use a rectangular coordinate AC potentiometer to measure the difference. The verification process is relatively complex and the function is single. The original current transformer calibrator has been difficult to meet the technical requirements for verifying the product quality of new electronic current transformers. Therefore, it is very necessary to develop a new type of current transformer calibrator.
The current transformer calibrator has distinct microcomputer-based instrument characteristics, and many of its functions are implemented by software. The feature of this development scheme is to virtualize the functional circuits of the original current transformer calibrator, and use software to measure multiple performance indicators such as ratio error, phase error, frequency, and harmonic content of the verified current transformer. This new type of transformer calibrator mainly consists of a signal conditioning unit, data acquisition, and calibration software programs.
The display soft panel of the new current transformer calibrator is equivalent to the front panel of the original calibrator. On this soft panel, the sampling channel, data scanning rate, data reading rate, and cache size of the calibrator's data acquisition card can be directly set. The soft panel is connected to the instrument's graphical program through a port. The graphical program, i.e., the calibration software, is the core of this new type of calibrator. It is compiled according to user needs, not only integrating all functions of the calibrator but also performing data transmission functions.
The portable current transformer calibrator developed based on virtual instrument technology has the following advantages:
1) This current transformer calibrator only consists of a signal conditioning box, a data acquisition card, a computer (or laptop), and corresponding measurement and calculation software. The device is small in size, light in weight, and easy to carry.
2) This calibrator can detect and analyze multiple technical performance indicators of the current transformer, such as ratio error, phase error, frequency, and harmonics. It can also output, store, or print them. The entire process is intelligently completed by the computer in the instrument, which not only greatly improves the calibration efficiency but also improves the calibration level through automatic compensation and correction of its own system errors. Moreover, it is easy to operate and significantly reduces the work intensity of calibration.
3) Its software-based composition characteristics determine that users can break through the limitation that the functions of traditional calibrators purchased in the past are specified by the manufacturer. They can conveniently modify or expand the functions of the instrument according to their own needs, realize custom development, and make it easy to develop current transformer calibrators that reflect different user needs.
4) Since it takes a PC as the core, it can be conveniently connected to various peripherals or networks. Using such a calibrator, current transformers distributed in different places can be verified, adapting to the needs of networked and automated measurement management, and has broad market prospects.
