Siemens 7SC80 Manual page 327

present and the binary input has been activated. The trip command can be blocked via binary inputs (no.
235.2115 >$00 BL.TripA ) and (no. 235.2114 >$00 BLK.TRIP ). The phase-selective blocking of the trip
command is required for interaction with the inrush restraint (see „Interaction with other functions"). The
function's dropout ratio can be set. If the threshold (>-element) is undershot after the pickup, the dropout
time delay will be started. The pickup is maintained during that time, a started trip delay time continues to
count down. If the trip time delay has elapsed while the dropout time delay is still during, the trip command
will only be given if the current threshold is exceeded. The element will only drop out when the dropout time
delay has elapsed. If the time is set to zero, the dropout will be initiated immediately once the threshold is
undershot.
External Trip Commands
The logic diagram does not explicitly depict the external trip commands since their functionality is analogous.
If the binary input is activated for external trip commands (no. 235.2112
treated as threshold overshooting, i.e. once it has been activated, the pickup time delay is started. If the
pickup time delay is set to zero, the pickup condition will be reported immediately starting the trip time delay.
Otherwise, the logic is the same as depicted in
Interaction with Other Functions
The flexible protection functions interact with a number of other functions such as the
•
Breaker failure protection:
The breaker failure protection is started automatically if the function initiates a trip. The trip will,
however, only take place if the current criterion is met at this time, i.e. the set minimum current
threshold 7006 50BF PICKUP has been exceeded.
•
Inrush restraint:
Direct interaction with the inrush restraint is not possible. In order to block a flexible function by the
inrush restraint, the blocking must be carried out in CFC. The flexible function provides three binary
inputs for blocking trip commands selectively for each phase (no. 235.2115 to 235.2117). They have to
be linked with the phase-selective indications for detecting the inrush (no. 1840 to 1842). Activating a
crossblock function requires the phase-selective inrush indications to be logically combined with the
binary input for blocking the function trip command (no. 235.2114
tion also needs to be delayed by at least 20 ms to make sure that the inrush restraint picks up before the
flexible function.
•
Entire relay logic:
The pickup signal of the flexible function is added to the general device pickup, the trip signal is added to
the general device trip (see also Section
device pickup and tripping are thus also applied to the flexible function.
After the picked up element has dropped out, the trip signals of the flexible protection functions are held
up at least for the specified minimum trip command time 210 TMin TRIP CMD.
Jump Detection
The jump detection determines positive and negative jumps of different measurands, for example for phase
currents, voltages, voltages of side 2, power values, power factor, or frequency.
This enables the jump detection to deliver a decision criterion for other protection functions by means of a
difference consideration, for example to localize a fault with adjacent devices.
The flexible protection functions offer all setting options to implement the jump detection for different quanti-
ties.
With the parameters OPERRAT. MODE and MEAS. QUANTITY, you can set the measurand to use. Select
Delta value as the MEAS. METHOD. If you want the positive jump to cause pickup, select the setting
Exceeding as PICKUP WITH, for the negative jump Dropping below.
The function calculates the positive and negative delta between the current values of the harmonic, for
example, of IA, IB, IC, and the values of the third from last cycle. If the present current is higher than the
current of the third from last cycle, a positive jump is detected. In the other case, the function detects a nega-
tive jump. Which cycle is evaluated depends on the selected measurand.
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
Figure 2-109.
2.25 Function Logic). All functions associated with general
2.19 Flexible Protection Functions
>$00 Dir.TRIP ), it will be logically
>$00 BLK.TRIP ). The flexible func-
Functions
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