ABB RELION REX640 Technical Manual page 422

Section 4
Protection functions
416
If the Enable voltage limit setting is set to "True", the magnitude of the
polarizing quantity is checked even if the Directional mode was set to
"Non-directional" or Allow Non Dir to "True". The protection relay
does not accept the Start value or Start value Mult setting if the
product of these settings exceeds the Start value setting range.
Typically, the ENA_MULT input is connected to the inrush detection function
INRHPAR. In case of inrush, INRPHAR activates the ENA_MULT input, which
multiplies Start value by the Start value Mult setting.
Directional calculation
The directional calculation module monitors the angle between the polarizing
quantity and operating quantity. Depending on the Pol quantity setting, the polarizing
quantity can be the residual voltage (measured or calculated) or the negative sequence
voltage. When the angle is in the operation sector, the module sends the enabling
signal to the timer module.
The minimum signal level which allows the directional operation can be set with the
Min operate current and Min operate voltage settings.
If Pol quantity is set to "Zero. seq. volt", the residual current and residual voltage are
used for directional calculation.
If Pol quantity is set to "Neg. seq. volt", the negative sequence current and negative
sequence voltage are used for directional calculation.
In the phasor diagrams representing the operation of DEFxPDEF, the polarity of the
polarizing quantity (Uo or U2) is reversed, that is, the polarizing quantity in the phasor
diagrams is either -Uo or -U2. Reversing is done by switching the polarity of the
residual current measuring channel (see the connection in the Protection relay's
physical connections section). Similarly the polarity of the calculated Io and I
switched.
For defining the operation sector, there are five modes available through the
Operation mode setting.
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REX640
Technical Manual