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Parameter: Blk. after fault extinction
•
Recommended setting value (_:13021:107) Blk. after fault extinction = yes
If the Blk. after fault extinction parameter is set to yes, the tripping delay is reset after the detec-
tion of the fault extinction. Therefore, if the tripping delay is set for a short time, the possibility of an overfunc-
tion is avoided. The reason for an overfunction is a slower attenuation in the zero-sequence system following
the fault extinction. Siemens recommends keeping this default setting if the stage is used for tripping.
To protect against intermittent ground faults, the stage uses the parameter Dropout delay to delay a
dropout due to fault extinction. If you are using the stage for protection against intermittent ground faults,
disable the blocking.
Parameter: Directional mode
•
Default setting (_:13021:106) Directional mode = forward
When a fault is detected, the selection of the parameter Directional mode defines whether the pickup of
the stage occurs in forward or backward direction.
Parameter: V0> threshold value
•
Default setting (_:13021:103) V0> threshold value = 15.000 V
With the parameter V0> threshold value, you define the sensitivity for the indication of the direction and
the pickup of the stage.
Note that the sensitivity of the direction determination itself is not influenced. The direction determination
always works with maximum sensitivity.
If high-resistive ground faults must also be reported, very sensitive settings are possible, for example, V0>
threshold value = 5 V secondary.
Parameter: Maximum operational V0
•
Recommended setting value (_:13021:105) Maximum operational V0 = 3.000 V
With the parameter Maximum operational V0, you define the maximum operational zero-sequence
voltage V0. If the fundamental-component value of the zero-sequence voltage V0 does not exceed the param-
eter Maximum operational V0 in a time slot of 100 ms after the function has started, the stage is reset.
The setting is made with reference to the zero-sequence voltage V0 according to its definition.
Network Structure
Radial network
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
Description
In radial networks, operational zero-sequence voltages are rather small.
Siemens recommends using the default value of 3.000 V.
Protection and Automation Functions
6.15 Sensitive Ground-Fault Detection
583
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