Functions
2.13 Flexible Protection Functions
SIPROTEC, 7SJ61, Manual
C53000-G1140-C210-1, Release date 02.2008
194
other Functions“). The dropout ratio of the function can be configured. Should undershooting of the set dropout
value occur after pickup (>-element), then the dropout delay time is started. Pickup is further maintained during
this time and a started trip command delay time continues to run. Should the trip command delay time expire
while the dropout delay time is still running, a trip command will occur only be generated if the threshold value
is exceeded at this time. Only upon expiry of the dropout delay time, the pickup drops out. If the time is config-
ured to zero, the dropout occurs immediately upon undershooting of the threshold value.
Direct Coupling
The direct coupling is not explicitly shown in the logic diagram as the functionality is analogous. When the
binary input to the direct coupling (Fno. 235.2112
„>$00 Dir.TRIP“
) is activated, this is treated like an ex-
ceeding of the threshold value, i.e. the pickup delay time is started upon activation. If it is set to zero, the pickup
is reported immediately and the trip command delay time is started. The logic functions as illustrated in Figure
2-67.
Interaction with other Functions
The flexible protection functions interact with different other functions, e.g.
• with the Circuit-breaker Failure Protection:
The circuit-breaker failure protection is automatically started if the function generates a trip command. How-
ever, tripping only occurs if the current criterion is fulfilled at that time, i.e. the set minimum current threshold
7006
50BF PICKUP
is exceeded.
• With the Automatic Reclosure Function (AR):
Initiation of the AR cannot occur directly. For interaction with the AR, the trip command of the flexible function
must be linked via CFC with binary input Fno. 2716
„>Start 79 Ph“
or Fno. 2715
„>Start 79 Gnd“
.
If operating time is used, the pickup of the flexible function must be linked additionally with the binary input
Fno. 2711
„>79 Start“
.
• With the Inrush Restraint:
A direct interaction with the inrush restraint is not possible. If a flexible function is supposed to be blocked
by the inrush restraint, this blocking must be carried out via CFC. For a phase-selective operation method,
the flexible function makes provision for three binary inputs for a phase-selective trip-command blocking
(Fno. 235.2115 to 235.2117). These must be linked with the phase-selective messages for recognition of
the inrush currents (Fno. 1840 to 1842). If a cross-blocking is to be implemented, the phase-selective inrush
messages are logical OR must be linked to the binary input for blocking the trip-command function (Fno.
235.2114
„>$00 BLK.TRIP“
). It if further important to note that the flexible function must be delayed by at
least 20 ms so that the inrush restraint can pickup safely before the flexible function.
• With the Overall Device Logic:
The pickup message of the flexible function is included in the general fault detection, and tripping in the
general trip (see Chapter 2.16). All functionalities linked to the general fault detection and general trip there-
fore also apply to the flexible function.
The trip commands by the flexible protection function are maintained after reset of the pickup for at least the
configured minimum trip-command duration 210 T TRIPCOM MIN.