Siemens 6MD85, Manual

Page: 633 / 1256

Application and Setting Notes (Advanced Stage)
Parameter:
Dynamic settings
•
Default setting
(_:661:26) Dynamic settings
=
no
Parameter Value Description
no
The influence on the overcurrent-protection stage by device-internal or
external functions is not necessary.
yes
If a device-internal function (automatic reclosing function or cold-load
pickup detection) or an external function should affect the overcurrent-
protection stage (such as change the setting of the threshold value or time
delay, blocking of the stage), the setting must be changed to
yes
.
This makes the configuration parameters
Influence of function...
as well as the dynamic settings
Threshold
,
Operate delay
and
Stage
blocked
of the stage visible and enables the settings to be set for the
specific influence.
Influence of AREC
The example of how the overcurrent stage (1st stage) can be used as a fast stage before automatic reclosing
describes the influence exerted by AREC.
The setting of the overcurrent stage (1st stage) results from the time-grading schedule. Additionally, it is to be
used as fast stage before an automatic reclosing. Because a fast disconnection of the short-circuit current
takes priority over the selectivity prior to reclosing, the tripping delay can be set to
0
or a very small value. To
achieve the selectivity, the final disconnection must be done with the grading time.
AREC is set to 2 reclosings. A secondary
Threshold
of
1.5 A
and a
Operate delay
of
600 ms
are
assumed (according to the time-grading schedule) for the overcurrent-protection stage. The standard settings
of the stage are set to these values.
To realize the application, the configuration settings
Effected by AR cycle 1
and
Effected by AR
cycle 2
are changed in the example to
yes
(= influenced). This activates the
AR cycle 1
and
AR cycle
2
input signals within the stage. When they become active, they switch to the assigned dynamic settings.
The two dynamic settings
Operate delay
assigned to these input signals (sources of influence) are set to
the time delay
0
(instantaneous tripping). The two dynamic settings
Threshold
assigned to these input
signals are set to the normal threshold value of
1.5 A
.
If the threshold value (
1.5 A
) is exceeded before AREC 1 and AREC 2, the overcurrent-protection stage trips
instantaneously. If the fault still exists after AREC 2 (unsuccessful AREC), the stage trips with the time delay of
600 ms
according to the time-grading schedule.
Influence of External Devices
The influence of an external device can also be configured. The above is an example of how the overcurrent-
protection stage (1st stage) can be used as a fast stage before automatic reclosing, in which case the AREC
function is performed by an external device.
To realize the application, the configuration setting
Effected by binary input
must be changed to
yes
(= influenced). This activates the
>Activ. dyn. settings
input signal within the stage. When the input
signal becomes active, it switches to the assigned dynamic settings. The external device must provide the
Cycle 1
and
Cycle 2
signals or, alternatively, the
AR ready
signal. The signals must be connected with
the binary input signal
>Activ. dyn. settings
.
The dynamic setting
Operate delay
, which is assigned to the input signal (source of influence)
>Activ.
dyn. settings
, is set to the time delay
0
(instantaneous tripping). The dynamic setting
Threshold
assigned to this input signal is set to the normal threshold value of
1.5 A
.
If the threshold value (
1.5 A
) is exceeded before AREC 1 and AREC 2, the overcurrent-protection stage trips
instantaneously. If the fault still exists after AREC 2 (unsuccessful AREC), the stage trips with the time delay of
600 ms
according to the time-grading schedule.
7.4.8.2
Protection and Automation Functions
7.4 Overcurrent Protection, Phases
SIPROTEC 5, High-Voltage Bay Controller, Manual 633
C53000-G5040-C015-9, Edition 11.2017