2.18 Protection Function Control
177
7ST6 Manual
E50417-G1176-C251-A3
2.18.1.3 Pickup Logic for the Entire Device
Pickup Indications
The fault detection logic combines the fault detection (pick-up) signals of all protection
functions. The group alarms
„Relay PU“
and
„Protection PU“
are available re-
spectively for a general device pickup and a general pickup of the protection functions.
The above indications can be allocated to LEDs or output relays. They can also be
used for local display, and for transfer of the indications to a personal computer or a
control centre.
General Device
Pickup
The pickup signals are combined with OR and lead to a general pickup of the protec-
tion device. It is signaled with the alarm
„Protection PU“
. If no protection function
of the device has picked up any longer,
„Protection PU“
disappears (indication:
„OFF“).
The general pickup is a prerequisite for a number of internal and external consequen-
tial functions. The following are among the internal functions controlled by general
device pickup:
• Start of trip log: From general device pickup to general device dropout, all fault in-
dications are entered in the trip log.
• Initialization of oscillographic records: The storage and maintenance of fault values
can also be made dependent on the occurrence of a trip command.
• Generation of spontaneous indications: Certain fault indications can be displayed
as so-called spontaneous indications (see „Spontaneous Indications“ below). This
indication can also be made dependent on the general device trip.
• Start action time of automatic reclosure (if available and used).
External functions may be controlled by this indication via an output contact. Examples
are:
• Automatic reclose devices.
• Channel boost in conjunction with signal transmission by PLC.
• Further additional devices or similar.
Spontaneous Indi-
cations
Spontaneous indications are fault indications which appear in the display automatical-
ly following a general fault detection or trip command of the device. In the case of 7ST6
they are the following:
„Relay PICKUP“:
Protective function that picked up;
„S/E/F TRIP“:
Protective function that tripped;
„PU Time“
:
Operating time from the general pickup to the dropout
of the device, in ms;
„TRIP Time“
:
Operating time from general pickup to the first trip
command of the device, the time is given in ms;
„Xpri =“
:
X (primary) (Xpri=);
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