Siemens 6MD85, Руководство пользователя

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Pickup Mode
With the
Pickup mode
parameter, you define whether the stage picks up when there is a lower threshold-
value violation in one measuring element (
1 out of 3
) or when there is a lower threshold-value violation in
all 3 measuring elements (
3 out of 3
).
Pickup Delay
The
Pickup delay
parameter is only available and of relevance if you are using the current-flow criterion of
the function (parameter
Current-flow criterion
=
on
).
If the circuit breaker opens when the current-flow criterion is being used, the undervoltage detection and
current-flow dropout functions conflict with one another. Depending on the threshold value settings for
undervoltage detection and current-flow criterion, it is possible that the undervoltage is detected before the
current-flow criterion has dropped out. In this case, the stage picks up briefly. Use the
Pickup delay
param-
eter to prevent the stage from briefly picking up in this way when the circuit breaker opens. This is achieved
by delaying pickup by approximately 40 ms.
Current-Flow Criterion
The undervoltage protection stages work optionally with a current-flow criterion. The
Current-flow
criterion
works across all tripping stages.
When the
Current-flow criterion
parameter is activated, the undervoltage protection stages only pick
up if a settable minimum current (
Threshold I>
) is exceeded. A current below the minimum current blocks
the stages.
The current-flow criterion can also be set to fulfilled with the binary input signal
>Current flow-crite-
rion
. The function reports when the current-flow criterion is fulfilled.
Figure 7-150 illustrates the influence of the current-flow criterion.
i
i
NOTE
If the
(_:2311:104) Current-flow criterion
parameter is deactivated, the device picks up imme-
diately if a missing measuring voltage is detected while the undervoltage protection is active. The param-
eter setting can be changed even when the device has picked up.
Blocking the Stage
In the event of blocking, the picked-up stage will be reset. The following blocking options are available for the
stage:
•
Via the binary input signal
>Block stage
from an external or internal source
•
From inside on pickup of the Measuring-voltage failure detection. The
Blk. by meas.-volt.
failure
parameter can be set so that measuring-voltage failure detection blocks the stage or does not
block it.
•
From an external source via the binary input signal
>Open
of the function block
Volt.-transf. c.
b.
, which links in the tripping of the voltage-transformer circuit breaker. The
Blk. by meas.-volt.
failure
parameter can be set so that measuring-voltage failure detection blocks the stage or does not
block it.
Application and Setting Notes
Parameter: Pickup mode
•
Recommended setting value
(_:421:101) Pickup mode
=
1 out of 3
With the
Pickup mode
parameter, you specify whether the stage picks up when there is a lower threshold-
value violation in one measuring element (
1 out of 3
) or when there is a lower threshold-value violation in
all 3 measuring elements (
3 out of 3
).
7.16.4
Protection and Automation Functions
7.16 Undervoltage Protection with 3-Phase Voltage
808 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017