If the directional function shows “No direction” for only some of the three
phases, this probably means a wrong CTs/VT
s connection.
4. The measured impedance information is available under the same menu. These
values are not affected by the minimum operating current setting of ZDRDIR
or ZDMRDIR and the measured values are shown any time the load current is
higher than 3% of the base current:
• 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 505 378-UEN A Section 12
Checking the directionality
Line differential protection RED670 2.2 IEC 275
Commissioning manual
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