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1MRK 506 355-UEN A
Line distance protection REL670 2.1 IEC
Commissioning manual
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 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.
Section 11
Checking the directionality
247
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