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U/I(/ϕ) Pickup
7SA6 Manual
C53000-G1176-C156-2
(address 1611 ) is set to below the minimum short-circuit current (approx. 10 %). This
also applies to the phase currents during earth faults or double earth faults.
In address 1630 1ph FAULTS you can choose whether a phase–to–earth loop shall
be selected in an earthed network during single–phase pickup without earth current
–release). The setting 1ph FAULTS = phase-earth is useful if no or only little
(I
E
earth current can flow via the measuring point in the event of earth faults. With 1ph
FAULTS = phase to phase only the leading phase–phase loop is measured in
the event of a single–phase pick-up in the earthed network.
Two further general settings refer to the final times, i.e. the tripping times in a worst
case scenario for faults outside all distance zones. They should be set above the delay
times for distance zones providing a final back-up option (also see "Independent
Zones Z1 up to Z5" in Section 6.2.4.2).
The directional final time DELAY FORW. PU (address 1602 ) only works with short cir-
cuits in forward (line) direction if there is no impedance within a distance zone after
pick-up.
The non-directional final time DELAY NON-DIR. (address 1603 ) works for all short-
circuits if there is no impedance within a distance zone after pick-up.
The meaning of the settings can be seen from Figure 6-21. Iph> (section a, address
1611 ) is the minimum current as described in the previous section, Iph>> (section c)
is the overcurrent pick-up.
U
V
Load Range
60
U(Iϕ>)
50
U(I>>)
d
40
U(I>)
30
20
a
10
Iph>
1
Figure 6-21
Parameters of
In most cases the angular dependence is not required. Then the voltage-dependent
section b is valid which results in the characteristic a-b-c. When controlling with Uphe
in the addresses 1612 Uph-e (I>>) and 1613 Uph-e (I>) the voltages for
phase–to–earth are inserted to determine the voltage-dependent branch b; corre-
spondingly when using Uphph the voltages for phase–to–phase are set in the ad-
dresses 1614 Uph-ph (I>>) and 1615 Uph-ph (I>) . The relevant settings are
determined according to the "Pickup Mode" (see above).
The characteristic has to be set such that it is just below the minimum expected volt-
age at the maximum expected load current. If in doubt, check the pick-up conditions
in accordance with the U/I characteristic.
Pick-up only
e
at ϕ>
c
b
Pick-up Independent
from Angle
Iϕ>
Iph>>
2
U/I/ ϕ pick-up
Functions
I
3
I
N
6-39
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