Functions
6-105
7SA522 Manual
C53000-G1176-C119-2
For the inverse time overcurrent stage 3I
0P
it is possible to select from a variety of
curves depending on the version of the relay and the configuration (Section 5.1, ad-
dress
) that was selected. If an inverse overcurrent stage is not required, the ad-
dress
LVVHWWR(DUWK)DXOW2&
=
'HILQLWH7LPH
. The 3I
0P
–stage
can then be used as a fourth definite time stage (refer to “Definite Time Stages”
above). In the case of the ANSI–curves (address
(DUWK)DXOW2&
=
72&
$16,
) the following alternatives are available in the address
,QYHUVH
,
6KRUWLQYHUVH
,
/RQJLQYHUVH
,
0RGHUDWHO\LQY
,
9HU\LQYHUVH
,
([WUHPHO\LQY
and
'HILQLWHLQY
The curves and equations the curves are based on are illustrated in the technical data
(Section 10.9).
The setting of the pick-up threshold
(address
) is similar to the
setting of definite time stages (see above). In this case it must be considered that a
safety margin has already been included between the pick-up threshold and the set-
ting value. The stage only picks up when the measured signal is approximately 10 %
above the setting value.
The time multiplier setting
) is derived from the grad-
ing coordination chart which was set up for earth faults in the system.
In addition to the inverse current dependant time delay, a constant (fixed length) time
delay can also be set if this is required. The setting
(address
added to the time of the set curve.
Inverse Time Over-
current Stage with
Logarithmic–
Inverse Character-
istic
For the inverse time overcurrent stage with logarithmic inverse characteristic the op-
erating mode is initially set:
(address
). This stage can be set
to operate
forward
(usually towards line) or
reverse direction
(usually towards bus-
bar) or
non-directional
(in both directions). If an individual stage is not required, set
its mode to
inactive
.
For the inverse logarithmic curves (address
(DUWK)DXOW2&
=
72&/RJD
ULWKP
) the following can be set: address
=
/RJLQYHUVH
The curves and equations the curves are based on are illustrated in the technical data
(Section 10.5). Figure 6-63 illustrates the influence of the most important setting pa-
rameters on the curve.
(address
) is the reference value for all
current values, while
(address
) determines the beginning
of the curve, i.e. the lowest operating range on the current axis (referred to
). The timer setting
(address
) determines the start-
ing point of the curve (for 3
I
0
=
). The time factor
) changes the slope of the curve. For large currents,
(address
) determines the lower limit on the time axis. For currents larger
than 30·
the operating time no longer decreases.
Finally in address
a fixed time delay can be set as was done for
other curves. This, however, has almost the same effect as an increase of
(address
Summary of Contents for siprotec 7SA522
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Page 89: ...SIPROTEC 4 Devices 4 25 7SA522 Manual C53000 G1176 C119 2 Figure 4 20 CFC Logic example ...
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Page 620: ...Appendix B 48 ...
