Siemens SIPROTEC 4, User Manual

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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 includes in particular:
Fault Detection / Pickup Logic
Processing Tripping Logic
Pickup Logic of the Entire Device
General Device Pickup
The pickup signals for all protection functions in the device are connected via an OR logic and lead to the
general device pickup. 4 It is initiated by the first function to pick up and drop 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 consequential functions. The
following are among the internal functions controlled by general device pickup:
•
Start of a trip log: From general device pickup to general device dropout, all fault messages are entered in
the trip log.
•
Initialization of Oscillographic Records: The storage and maintenance of oscillographic 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 reclosing devices,
•
Starting of additional devices, or similar.
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 tripping 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 2-136 ). At the same time, the minimum trip command duration
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 dura-
tion 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 either by pressing the LED reset key or by activating an appropriately
allocated binary input (
>Reset LED
). A precondition, of course, is that the circuit-breaker close coil – as usual
– remains blocked as long as the trip signal is present, and that the trip coil current is interrupted by the auxil-
iary contact of the circuit breaker.
2.24
2.24.1
2.24.2
Functions
2.24 Function Logic
SIPROTEC 4, 7SJ62/64, Manual 315
C53000-G1140-C207-8, Edition 08.2016