Technical requirements for high and low voltage switchgear

When a partial discharge occurs inside the high-voltage switchgear, most of the radio waves generated by charging and discharging are shielded by the plastic shell of the switchgear, and a small part of the radio waves will generate a transient working voltage to the ground according to the interface of the metal material shell. The detection camera is used to detect the outer layer of the metal shell, and the instantaneous potential difference change can reflect the partial discharge level inside the switchgear.

According to the arrangement of multiple detection cameras on the surface of the high-voltage switchgear, and add multiple electromagnetic interference collection cameras around the switchgear, continuous detection is carried out at the same time. According to the basic principle of time delay, the precise positioning of the partial discharge power supply in the switch cabinet can be completed.

Basic specifications

(1) The camera should be equipped with intelligent sensing technology to ensure that it can flexibly reflect the partial discharge inside the machine and equipment;

(2) The equipment display information page should be human-machine friendly, and ensure that the interface can display clear information in different natural environments, which is conducive to the rapid loading of on-site test engineers;

(3) The setting method of the main parameters (condition influence threshold, severe charge and discharge level threshold, etc.) should be simple and clear;

(4) The equipment should have the functions of basic estimation of partial discharge severity and timely display of characteristic quantities;

(5) The display content of partial discharge data should include common characteristic quantities that can reflect the development trend of partial discharge, such as the number of single pulses, the number of single pulses per cycle, relative severity, etc.;

(6) The partial discharge data display should conform to iec60270, and the PC value or DB value can be used. Combining with on-site standards, the decibel value method is proposed. Among them: DB=20log (MV), see appendix a for the correlation between DB and MV, the equipment should at least consider the provisions of appendix a, if the PC value method is selected, the calculation correlation between the PC value and the DB should be displayed;

(7) The equipment should have self-calibration and inspection functions. When using on site, quickly identify whether the equipment is normal;

(8) The design plan of the equipment should be conducive to the operation of on-site staff;

(9) The system software should have a certain ability to record data and information, and at least consider the ability to accumulate and store data and information within a week;

(10) The data information coaxial cable between the camera and the server should be shielded by coaxial output, and the characteristic impedance should be consistent with the input resistance of the server;

(11) The camera should be built-in, and the contact between the camera and the machine should be sufficiently reliable;

(12) The system software simultaneously detects the total number of connected cameras should have strong scalability and be suitable for the optimal detection of the total number of different switchgear groups;

(13) The equipment should have good zero-drift suppression capability;

(14) There are several adjustable options for the display of data information recording interval.

The high-voltage switchgear temperature measuring device is designed and operated by a high-performance single-chip microcomputer. Compared with the traditional power switch status indicator, the function of the intelligent system is improved. In addition to displaying the on and off information of the power switch, it can also be distinguished and emphasized that the power switch car is in the middle of the experimental part and the working part, outside the cabinet door. In addition, the video and voice anti-touch reminder function, the data dashboard function and the over-temperature alarm function have also been improved.