The primary load impedance must have an angle (PHI) between the setting angles for
the directional lines. In case of default settings this means:
• for forward (exported) load: -15 deg < PHI < 115 deg
• for reverse (imported) load: 165 deg < PHI < 295 deg
The settings for forward load: - ArgDir < PHI < ArgNegRes and the settings for
reverse load: 180 deg - ArgDir < PHI < 180 deg + ArgNegRes included in the
directional functions ZDRDIR or ZDMRDIR are available under the HMI menu:
• Main menu/Settings/IED Settings/Impedance protection/
DirectionalImpedance
3. The directionality of the load current is shown by the High speed distance protection
ZMFPDIS or ZMFCPDIS under the HMI menu: Main menu/Test/Function status/
Impedance protection/HighSpeedDistance or by the directional function ZDRDIR
or ZDMRDIR and it is available under the HMI menu: Main menu/Test/Function
status/Impedance protection/DirectionalImpedance
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
Section 13 1MRK 504 165-UUS -
Checking the directionality
294 Transformer protection RET670 2.2 ANSI
Commissioning manual
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