Functions
6-128 7SA6 Manual
C53000-G1176-C156-2
The instantaneous tripping following manual closure is blocked as long as the inrush-
stabilization recognizes a rush current. This prevents instantaneous tripping by a
stage which, under normal conditions, is sufficiently delayed during energization of a
transformer.
6.7.2 Applying the Function Parameter Settings
During the configuration of the device functions (refer to Section 5.1, address 131
Earth Fault O/C
) it was determined which characteristics of the overcurrent time
protection would be available. Depending on the configuration selected there, and the
ordered version of the relay, only those parameters applicable to the available curves
are accessible now.
By means of the parameter
3101 FCT EarthFltO/C the earth fault protection can
be switched
On or Off. This refers to all functions of the earth fault protection.
Each individual stage, if not required, can be set to
Inactive (see below).
Blocking Theearthfaultprotectioncanbeblockedbythedistanceprotectiontogivepreference
to the selective fault clearance by the distance protection over tripping by the earth
fault protection. In setting address
3102 BLOCK for Dist. it is determined whether
blocking is done during each fault detection of the distance protection (
every Pick-
up
) or only during single-phase fault detection by the distance protection (single-
phase Pickup
) or only during multiple-phase fault detection by the distance protec-
tion (
multi-phase Pickup). If blocking is not required, the setting No is applied.
The earth fault protection should be blocked during single-pole automatic reclose
dead time, to avoid pick-up with the false zero sequence values arising during this
state (address
3103 BLOCK 1pDeadTim). A setting of Yes is therefore only required
if single-pole tripping is possible. Otherwise the setting
No (presetting) remains.
Definite Time
Stages
First of all, the mode for each stage is set: Op. mode 3I0>>> (address 3110),
Op. mode 3I0>> (address 3120)andOp. mode 3I0> (address 3130). Each stage
can be set to operate
Forward (usually towards line) or Reverse direction (usually
towards busbar) or
Non-Directional (in both directions). If a single stage is not re-
quired, set its mode to
Inactive.
Thedefinitetimestages
3I0>>> (address 3111), 3I0>> (address 3121)and3I0>
(address 3131) can be used for a three-stage definite time overcurrent protection.
Theycanalsobecombinedwiththeinversetimestage
3I0p PICKUP (address 3141,
see below). The pick up thresholds should in general be selected such that the most
sensitive stage picks up with the smallest expected earth fault current.
The 3I
0
>> und 3I
0
>>> stages are best suited for fast tripping stages (instantaneous),
as these stages use an abridged filter with shorter response time. On the other hand,
the stages 3I0> and 3I0p are best-suited for very sensitive earth fault detection due to
their effective method of suppressing harmonics.
If no inverse time stage but rather a fourth definite time stage is required, the “inverse
time” stage can be implemented as a definite time stage. This must already be taken
regard of during the configuration of the protection functions (refer to Section 5.1,
address
131 Earth Fault O/C = Definite Time). For this stage, the address
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