Supervisory Functions
155
7SS52 V4 Manual
C53000-G1176-C182-3
(
6310/CU
) is used to set the response of the pro-
tection after pickup of the differential current supervision.
With setting
a pickup of the differential current supervision causes only
an alarm and not a blocking of the protection.
the protection will be blocked for the duration of the malfunc-
tion. Phase- and bus zone-selective blocking is performed if the parameter
6305/CU
) is set accordingly.
With setting
the blocking of the affected phase and zone is treated
as with
. It differs from the setting
in that the protection is re-
leased by an operator input ”
” or a binary input ”
BI FNo. 6/CU
) as soon as the malfunction is eliminated.
(
6311/CU
) is used to set the response of the pro-
tection after pickup of the differential current supervision.
With setting
a pickup of the differential current supervision causes only
an alarm and not a blocking of the protection. You should select this setting if you want
to set the protection to maximum selectivity.
the protection will be blocked for the duration of the malfunc-
tion.
If a malfunction occurs in the check zone, the corresponding phase of the protection
is blocked completely. The blocking is released as soon as the value that initiated it
drops below the pickup threshold.
With setting
the blocking of the affected phase and zone is treated
as with
. It differs from the setting
in that the protection is re-
leased by an operator input ”
BI FNo. 6/CU
) as soon as the malfunction is eliminated.
When an external fault is tripped by an external protection device, linearized current
transformers with TPZ cores may carry during the demagnetizing phase a DC compo-
nent that mimicks a fault in the protection zone.
In order to avoid spurious tripping, the differential current may be monitored for the
presence of a pure DC component. For this purpose the zero crossing supervi-
sion
) must be activated.
the zero crossing supervision will be activated.
the zero crossing supervision will be deactivated.
The parameter
6313A/CU
) is used to set the threshold of the differential
current for the zero crossing supervision.
Set this limit value to 50% of the corresponding limit value for the differential current
in the parameters
Id> BZ
(
6102/CU
) and
Id> CZ
(
6104/CU
), or
Id> BZ - EF
(
6109A/CU
) or
Id> CZ - EF
(
6111A/CU
), using the earth fault characteristic.
The DC component monitoring is performed for each measuring system. The differen-
tial current of the selective protection zones and of the check zone is compared with
the set threshold.
f the zero crossings of the current do not recur at the latest after 32 ms (f
N
=
50 Hz) or
27 ms (f
N
=
60 Hz), the measuring system assumes a DC current and issues a selec-
tive blocking command to the protection. The blocking is maintained until the current
drops below the threshold again.
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