ABB REG650 Technical Manual page 151

1MRK 502 043-UUS B
Technical Manual
In LEXPDIS (40) function the zone measurement is done as shown in figure 64.
Offset
XoffsetZ1
Z1diameter
IEC06000456 V2 EN
Figure 64: Zone measurement in LEXPDIS (40) protection function
The impedance Z1 is constructed from the measured apparent impedance Z and the
impedance corresponding to the centre point of the impedance characteristic (Z1 or
Z2). If the magnitude of this impedance is less than the radius (diameter/2) of the
characteristic, this part of the protection will operate.
If the directional restrain is set Disabled the impedance zone operation will start the
appropriate timer and LEXPDIS (40) will trip after the set delay (tZ1 or tZ2).
If the directional restrain is set Enabled the directional release function must also
operate to enable operation. A new impedance is constructed from the measured
apparent impedance Z and the XoffsetDirLine point on the y-axis. If the phase angle of
this impedance is less than the set DirAngle LEXPDIS (40) function will be released,
see figure 65.
Impedance protection
R
Z (apparent impedance)
Z1 = Z - (XoffsetZ1 +
Z1diameter/2)
Z1 or Z2
en06000456-2.vsd
Section 7
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