Functions
2.15 Flexible Protection Functions
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
186
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 time delay 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 thresh-
old 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 „>$00 Dir.TRIP“), it will be logically
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. Other-
wise, the logic is the same as depicted in Figure 2-77.
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 (Power
System Data 1) has been exceeded.
• With the Automatic Reclosure Function (AR):
The AR cannot be started directly. To cooperate with AR, the trip command of the flexible function must be
linked with the binary input FNo. 2716 „>79 TRIP 3p“ via CFC. To use an action time, the pickup of the
flexible function must additionally be linked to the binary input FNo. 2711 „>79 Start“.
• Fuse-Failure-Monitor (see description at „Blocking Functions“).
• With inrush restraint:
A direct cooperation with the inrush restraint is not possible. If a flexible function is to be blocked by the
inrush restraint, this blocking must be configured via CFC. Furthermore, please note that the flexible function
must be delayed by at least 20 ms to enable the inrush restraint to pick up reliably before the flexible function.
• With the overall device logic:
The pickup indication of the flexible function is included in the general pickup, and the tripping in the general
trip. All functionalities associated with the general pickup and general trip therefore also apply to the flexible
function.
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