ABB REG650 Technical Manual page 133

1MRK 502 034-UEN -
Technical Manual
XoffsetZ1
Z1diameter
IEC06000456 V2 EN
Figure 65: Zone measurement in LEXPDIS protection function
The impedance Z1 is constructed out from the measured apparent impedance Z and
the impedance corresponding to the centre point of the impedance characteristic
(Z1 or Z2). If the amplitude 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 off the impedance zone operation will start the
appropriate timer and LEXPDIS will trip after the set delay (tZ1 or tZ2).
If the directional restrain is set On the directional release function must also
operate to enable operation. A new impedance is constructed as XoffsetDirLine. If
the phase angle of this impedance is less than the set DirAngle LEXPDIS function
will be released, see figure 66.
Offset
Z (apparent impedance)
Z1 = Z - (XoffsetZ1 +
Z1diameter/2)
Z1 or Z2
en06000456-2.vsd
Section 6
Impedance protection
R
127