The impedance characteristic is a distance protection action characteristic of the protective relay. When you want to detect the action boundary of the impedance characteristic of the protective relay, you need to use a microcomputer relay protection tester to detect it. That is, the impedance action boundary of various characteristics such as polygon characteristics, straight lines, arcs, and circular characteristics are searched out in one period.

Before using the microcomputer relay protection tester to detect the impedance characteristics of the protective relay, we need to determine the test items, pay attention to the intelligent selection of the Z (I) characteristic curve, the impedance boundary search or the Z (V) characteristic curve in the single test. One is tested. Set the operation interface according to different test items. For example, the "search mode" is divided into two calculation models: "current constant" and "voltage constant".

When we select the "search impedance boundary" test item, the radial scan line should be set during the operation of the instrument. The parameter settings of the scan line include: scan center, scan radius, scan step length, scan range, search angle, automatic setting of scan parameters, etc. Take the scan center as an example. This parameter should be set as close as possible to the center of the theoretical impedance characteristic diagram of the protection. You can directly enter the data or click to select the scan center. After modifying the scan center branch, the coordinates in the instrument will automatically adjust the position to ensure that the scan center is at the center of the graph.

Then there are tuning parameters, and the instrument can be tested without theoretical impedance boundary graphics. But if there is a theoretical diagram, it is easier for the experimenter to determine the center point of the search and the length of the search line. For details of the theoretical drawing, please refer to the instruction manual of the instrument.