2 Functions
162
7SA522 Manual
C53000-G1176-C155-3
External signaling of the phase-selective pickup is accomplished via the information
´()/VHOHFµ 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 2-71 Logic diagram of single-pole tripping with phase selector
Blocking Tripping of the earth fault protection can be blocked by the distance protection. If then
the distance protection detects a fault, the earth fault protection will not be tripped. 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
40 ms to prevent signal race conditions. It is issued as fault indication ´()75,3
%/2&.µ (FNo 1335).
The earth fault protection can also be blocked during the single-pole dead time of an
automatic reclose cycle. This prevents an incorrect measurement resulting from the
zero sequence current and voltage signals arising in this state. The blocking affects
the entire protection function and is maintained for approximately 40 ms after reclo-
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