load impedance has an angle which is outside the above given valid angles for
determining forward or reverse direction.
If the directional function shows “No direction” for only some of the three
phases, this probably means a wrong CTs/VTs connection.
4. The measured impedance information is available under the same menu. These
values are not affected by the minimum operating current setting and the
measured values are shown any time the load current is higher than 3% of the
nominal current of the line:
• L1R
• L1X
• L2R
• L2X
• L3R
• L3X
The measured impedance information can still be used to determine the
direction of the load. A positive resistance measured in all phases indicates a
forward (exporting) resistive load (active power), while a negative sign
indicates a reverse (importing) resistive load (active power). Usually it is
enough to look at the resistive values to get information of the load direction,
that must anyway be compared with the indication given by external
equipment measuring the same power flow.
1MRK 502 029-UEN A Section 16
Checking the directionality
231
Installation and commissioning manual
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