The current transformer calibrator is a special instrument used for verifying current transformers. Traditional current transformer calibrators mostly adopt the difference principle to obtain the difference, and then use a rectangular coordinate AC potentiometer to measure the difference. The verification process is relatively complex and has a single function. 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 of the verified current transformer, such as ratio error, phase error, frequency, harmonic content, etc. This new type of transformer calibrator mainly consists of a signal conditioning unit, data acquisition, and calibration software programs.
The new current transformer calibrator has a display soft panel, which is equivalent to the front panel of the original calibrator. On this soft panel, the sampling channel, data scanning rate, data reading rate, and buffer 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) The current transformer calibrator consists only 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) The 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 the system's own errors. Moreover, it is easy to operate and significantly reduces the work intensity of calibration.
3) Its software-based composition feature determines that users can break through the limitations of traditional calibrators whose functions are specified by manufacturers. Users can conveniently modify or expand the instrument's functions according to their own needs, achieving custom development, making it easy to develop current transformer calibrators that reflect different user needs.
4) Since it is PC-based, it can be easily connected to various peripherals or networks. With such a calibrator, current transformers distributed in different places can be verified, adapting to the networked and automated needs of measurement management, and has broad market prospects.
