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2.22 Function Logic
312
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
2.22 Function Logic
The function logic coordinates the execution of protection and auxiliary functions, it
processes the resulting decisions and information received from the system. This in-
cludes in particular:
– Fault Detection / Pickup Logic
– Processing Tripping Logic
2.22.1 Pickup Logic for the Entire Device
General Pickup The pickup signals for all protective functions in the device are connected via an OR
logic, and lead to the general device pickup. It is initiated by the first function to pickup
and drops out when the last function drops out. As a consequence, the following
message is reported: 501
„Relay PICKUP“
.
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 drop out, all fault
messages are entered in the trip log.
• Initialization of Oscillographic Records: The storage and maintenance of oscillo-
graphic values can also be made dependent on the general device pickup.
Exception: Apart from the settings
ON
or
OFF
, some protection functions can also be
set to
Alarm Only
. With setting
Alarm Only
no trip command is given, no trip log
is created, fault recording is not initiated and no spontaneous fault annunciations are
shown on the display.
External functions may be controlled via an output contact. Examples are:
• Automatic reclose devices,
• Starting of additional devices, or similar.
2.22.2 Tripping Logic of the Entire Device
General Tripping The trip signals for all protective functions are connected by OR and generate the
message 511
„Relay TRIP“
.
This message can be configured to an LED or binary output, just as the individual trip-
ping messages can.
Terminating the
Trip Signal Once the trip command is output by the protection function, it is recorded as message
„Relay TRIP“
(see figure 2-112). At the same time, the minimum trip command du-
ration
TMin TRIP CMD
is started. This ensures that the command is transmitted to
the circuit breaker for a sufficient amount of time, even if the function which issued the
trip signal drops out quickly. The trip commands can be terminated first when the last
protection function has dropped out (no function is in pickup mode) AND the minimum
trip signal duration has expired.
Finally, it is possible to latch the trip signal until it is manually reset (lockout function).
This allows the circuit-breaker to be locked against reclosing until the cause of the fault
has been clarified and the lockout has been manually reset. The reset takes place