Relay protection tester boundary measurement
Automatically determines the two operating boundaries of directional protection and calculates the maximum sensitivity angle. In the “Display Operating Angle Vector Diagram” mode, the two boundary lines and the maximum sensitivity line can be clearly observed from the graph on the right side of the main interface.
Test Parameters
Select a voltage and current output, vary the phase angle (U, D) within a given range, and test the left and right action boundaries.
Since protection is typically implemented using a 90° wiring method, the line voltage and the phase current of the third phase are generally used during testing—for example, voltage UAB and current IC. Sometimes, one phase voltage and one phase current can also be selected for testing, but line currents are usually not chosen. Note that the values of the selected voltage and current can be set, while the voltages of the unselected phases are all equal to the rated voltage with symmetrical angles, and the currents of the unselected phases are all zero.
When setting the search range for (U, I), first determine the set value of the protection device’s “maximum sensitivity angle.” The search range should cover the actual two trip boundaries of the protection. That is, both the starting and ending values of the search must be set outside the operating zone, so that the tester searches from the “non-operating zone” toward the “operating zone.”
The protection does not operate at the beginning of the search. When the angle changes to a certain value, the protection operates—indicating that an operating boundary has been found—and a line is drawn on the graph. The search direction is then immediately reversed to locate the other boundary angle (note: at this point, the starting angle output by the relay protection tester becomes the preset “search end value”). When the second operating boundary is identified, the software draws another line. After calculating the maximum sensitivity line, the software automatically marks it on the graph.
Relay Protection Tester Action Angle Definition
Select the operating angle as “Test Phase Angle,” “(U0, I0),” or “(U2, I2)” according to the type of protection being tested. For conventional directional power or impedance relays, choose “Test Phase Angle,” which is the phase angle between the selected test voltage and current. For zero-sequence or negative-sequence protection, select either (U0, I0) or (U2, I2).
Vector image display
When “Display Three-Phase Voltage and Current Vector Diagram” is selected, the diagram shows vector representations of the voltages and currents for each phase. When “Display Action Angle Vector Diagram” is selected, only the voltage and current values corresponding to the chosen action angle are displayed. For example, selecting (U2, I2) will display only the magnitude and phase angle of U2 and I2. This display method facilitates a clear and intuitive observation of the search process for the operating boundary.
Post time: Jul-30-2026