ABB RELION REX640 Technical Manual page 347

1MRS759142 F
Table 391: Polarizing quantities
Polarizing quantity
Pos. seq. volt
Neg. seq. volt
Self pol
Cross pol
The directional operation can be selected with the
user can select either "Non-directional", "Forward" or "Reverse" operation. By setting
the value of
the directional information is invalid.
The
value of
in the operating direction are seen in the operating zone and all the faults in the
opposite direction are seen in the non-operating zone. The value of
angle depends on the network configuration.
Reliable operation requires both the operating and polarizing quantities to exceed
certain minimum amplitude levels. The minimum amplitude level for the operating
quantity (current) is set with the
amplitude level for the polarizing quantity (voltage) is set with the
voltage setting. If the amplitude level of the operating quantity or polarizing
quantity is below the set level, the direction information of the corresponding phase
is set to "Unknown".
The polarizing quantity validity can remain valid even if the amplitude of the
polarizing quantity falls below the value of the
case, the directional information is provided by a special memory function for a
time defined with the
DPHxPDOC is provided with a memory function to secure a reliable and correct
directional protection relay operation in case of a close short circuit or an earth
fault characterized by an extremely low voltage. At sudden loss of the polarization
quantity, the angle difference is calculated on the basis of a fictive voltage. The
fictive voltage is calculated using the positive phase sequence voltage measured
before the fault occurred, assuming that the voltage is not affected by the fault.
The memory function enables the function to operate up to a maximum of three
seconds after a total loss of voltage. This time can be set with the
time setting. The voltage memory cannot be used for the "Negative sequence
voltage" polarization because it is not possible to substitute the positive sequence
voltage for negative sequence voltage without knowing the network unsymmetry
level. This is the reason why the fictive voltage angle and corresponding direction
information are frozen immediately for this polarization mode when the need for
a voltage memory arises and these are kept frozen until the time set with
Mem time elapses.
When the voltage falls below
is used to determine the phase angle. The measured voltage is applied again as
soon as the voltage rises above
voltage is also discarded if the measured voltage stays below
and hysteresis for longer than
REX640
Technical Manual
Allow Non Dir to "True", the non-directional operation is allowed when
Characteristic angle setting is used to turn the directional characteristic. The
Characteristic angle should be chosen in such a way that all the faults
Voltage Mem time setting.
The value for the
since the accuracy in low signal levels is strongly affected by the
measuring device accuracy.
Description
Positive sequence voltage
Negative sequence voltage
Self polarization
Cross polarization
Min operate current setting. The minimum
Min operate voltage setting. In this
Min operate voltage setting should be carefully selected
Min operate voltage at a close fault, the fictive voltage
Min operate voltage and hysteresis. The fictive
Voltage Mem time or if the fault current disappears
Protection functions
Directional mode setting. The
Characteristic
Min operate
Voltage Mem
Min operate voltage
Voltage
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