Siemens 7SA511 manual July 27

7SA511 Line Protection Relay Chapter 7

4. Press the 4L21E?key02Ito continueMPEDAtoNtheCEnextSaddress, 4202 in the example shown below.

5.Press the Yeskey to confirm checking the active and reactive component of the load impedance for the indicated loop. The message “IN PROGRESS” will appear in the second line of the display until the test is complete. When complete, the calculated values will appear in the displayXRr=as shown belownnn(refer also to Figure 7-1).

The n’s in this example display represent the

actual numeric values that should appear in the relay’s display.

6. Repeat steps 2 through 5 of this procedure for each of the six measurement loops.

Provided that the direction is indicated, all six measurement loops should indicate the same, known direction of the load flow. If all directions are wrong, then the polarity of the measuring transformers and the programmed setting at address 1101 (polarity) do not agree. Check the polarity and program correctly. If the indicated directions for the individual phases differ (e.g. phase 1 is forward and phase 2 is reverse), either the individual phase connections in the transformers are interchanged or the polarity connections are not correct. Check the connections.

Capacitive loads caused by under-excited generators or charging currents can frequently result in undefined or inconsistent directional information. By means of the load impedance calculation, the position of the load impedance vector can be determined. The load impedances allow determination of the position of the load impedance vector as shown in the R/X diagram in Figure 7-1.

July 27, 1995 7-7