ABB RET650 2.1 IEC Commissioning Manual page 108

Section 11
Checking the directionality
102
The following will be shown if the load current flows in forward (exporting)
direction:
• L1Dir = Forward
• L2Dir = Forward
• L3Dir = Forward
The following will be shown if the load current flows in the reverse direction
(importing):
• L1Dir = Reverse
• L2Dir = Reverse
• L3Dir = Reverse
Compare this result with the information given by the external equipment, it must
be the same. If the direction of the three phases is not the same, this is a sign of
incorrect connection of the voltage or current transformers serving the distance
protection function. It is also possible that there is a wrong setting for the earthing
point for one or more of the CTs serving distance protection (the setting name is:
CTStarPoint available under the HMI menu:Main menu/Configuration/
Analog modules).
If the directional function shows forward when it should show reverse (or vice-
versa) for all the three phases, this probably means a wrong connection of CTs
and/or VTs serving the distance protection, or it can mean a wrong setting of
earthing point (the setting name is : CTStarPoint) for all the three CTs, or it could
mean a wrong setting for the pre-processing blocks (3PhaseAnalogGroup under
the HMI menu: Main menu/Configuration/Analog modules) connected to the
CTs/VTs and serving the distance protection (verify that no wrong negation has
been set; the setting name is: Negation).
If the directional function shows "No direction" for all the three phases it can
mean that the load current is below the minimum operating current or that the 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 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
1MRK 504 160-UEN -
Transformer protection RET650 2.1 IEC
Commissioning manual