Siemens SIPROTEC 7SJ62 Manual page 288

Functions
2.17 Flexible Protection Functions
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 212
BkrClosed I MIN (Power System Data 1) has been exceeded.
• Automatic reclosing (AR):
The AR cannot be started directly. In order to interact with the AR, the trip command of the flexible function
needs be linked in CFC to binary input no. 2716 „>Start 79 Ph" or no. 2715.„>Start 79 Gnd". Using
an operating time requires the pickup of the flexible function to be linked to binary input no. 2711 „>79
Start".
• Fuse-Failure-Monitor (see description at „Blocking Functions").
• 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 block-
ing 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 re-
quires the phase-selective inrush indications to be logically combined with the binary input for blocking the
function trip command (no. 235.2114 „>$00 BLK.TRIP"). The flexible function 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 Chapter 2.22). All functions associated with general device pickup and trip-
ping 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 T TRIPCOM MIN.
288
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008