Siemens siprotec 7SD5 User Manual page 218

2 Functions
tripping is initiated anyway as soon as a multi-pole fault has been detected, as de-
scribed above.
Figure 2-96 shows the logic diagram. The phase determined by the phase selector
can be processed selectively for each phase, for example the internal information „E/F
PickupL1" etc. is used for phase-selective signal transmission.
External signaling of the phase-selective pickup is accomplished via the information
„E/F L1 selec." etc. They appear only if the phase was clearly detected. Single-
pole tripping requires of course the general prerequisites to be fulfilled (device must
be suited for single-pole tripping, single-pole tripping allowed).
Figure 2-96 Logic diagram of single-pole tripping with phase selector
Blocking The earth fault protection can be blocked by the distance protection. If in this case a
fault is detected by the distance protection, the earth fault protection will not trip. This
gives the selective fault clearance by the distance protection preference over tripping
by the earth fault protection. The blocking can be restricted by configuration to single-
phase or multi-phase faults and to faults in distance zone Z1 or Z1/Z1B. The blocking
only affects the time sequence and tripping by the earth fault protection function and
after the cause of the blocking has been cleared, it is maintained for approximately
40ms to prevent signal race conditions. It is issued as fault indication „EF TRIP
BLOCK" (No. 1335).
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7SD5 Manual
C53000-G1176-C169-1