ABB Relion 650 Series Technical Manual page 93

1MRK 506 326-UUS B
A current-based phase selection is also included. The measuring elements continuously measure
three phase currents and the residual current, and compare them with the set values. The current
signals are filtered by Fourier's recursive filter, and separate trip counter prevents too high
overreaching of the measuring elements.
The characteristic is basically non-directional, but FDPSPDIS (21) uses information from the
directional function (ZDNRDIR) to discriminate whether the fault is in forward or reverse direction.
The pickup condition STCNDZI is essentially based on the following criteria:
1. Residual current criteria, that is, separation of faults with and without ground connection
2. Regular quadrilateral impedance characteristic
3. Load encroachment characteristics is always active but can be switched off by selecting a
high setting.
The current pickup condition DLECND is based on the following criteria:
1. Residual current criteria
2. No quadrilateral impedance characteristic. The impedance reach outside the load area is
theoretically infinite. The practical reach, however, will be determined by the minimum
operating current limits.
3. Load encroachment characteristic is always active, but can be switched off by selecting a high
setting.
The DLECND output is non-directional. The directionality is determined by the distance zones
directional function (ZDNRDIR). There are outputs from FDPSPDIS (21) that indicate whether a
pickup is in forward or reverse direction or non-directional, for example FWD_A, REV_A and
NDIR_A.
These directional indications are based on the sector boundaries of the directional function and
the impedance setting of FDPSPDIS (21) function. Their operating characteristics are illustrated in
figure 41.
60°
Non-directional (ND)
ANSI05000668 V1 EN-US
Figure 41: Characteristics for non-directional, forward and reverse operation of Phase
Line distance protection REL650
Technical manual
X
60°
R
Forward (FWD)
selection with load encroachment, quadrilateral characteristic FDPSPDIS (21)
© Copyright 2011 ABB Power Grids. All rights reserved
X
60°
R
60°
Reverse (REV)
en05000668_ansi.vsd
Section 5
Impedance protection
X
R
87