ABB RELION 650 SERIES, Technical Manual

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• Input signal CACC is used for tripping of the communication scheme,
normally the start signal of a forward overreaching step of STFW.
• Input signal CSBLK is used for sending block signal in the blocking
communication scheme, normally the start signal of a reverse overreaching
step of STRV.
• Input signal CSUR is used for sending permissive signal in the underreaching
permissive communication scheme, normally the start signal of a forward
underreaching step of STINn, where n corresponds to the underreaching step.
• Input signal CSOR is used for sending permissive signal in the overreaching
permissive communication scheme, normally the start signal of a forward
overreaching step of STINn, where n corresponds to the overreaching step.
In addition to this a signal from the autoreclosing function should be configured to
the BLKCS input for blocking of the function at a single phase reclosing cycle.
12.4.6.1 Blocking scheme
M13922-9 v5
In the blocking scheme a signal is sent to the other line end if the directional
element detects an earth fault in the reverse direction. When the forward directional
element operates, it trips after a short time delay if no blocking signal is received
from the opposite line end. The time delay, normally 30 – 40 ms, depends on the
communication transmission time and a chosen safety margin.
One advantage of the blocking scheme is that only one channel (carrier frequency)
is needed if the ratio of source impedances at both end is approximately equal for
zero and positive sequence source impedances, the channel can be shared with the
impedance measuring system, if that system also works in the blocking mode. The
communication signal is transmitted on a healthy line and no signal attenuation will
occur due to the fault.
Blocking schemes are particular favorable for three-terminal applications if there is
no zero-sequence outfeed from the tapping. The blocking scheme is immune to
current reversals because the received signal is maintained long enough to avoid
unwanted operation due to current reversal. There is never any need for weak-end
infeed logic, because the strong end trips for an internal fault when no blocking
signal is received from the weak end. The fault clearing time is however generally
longer for a blocking scheme than for a permissive scheme.
If the fault is on the line, the forward direction measuring element operates. If no
blocking signal comes from the other line end via the CR binary input (received
signal) the TRIP output is activated after the
tCoord set time delay.
Section 12
1MRK 506 382-UEN A
Scheme communication
452 Line distance protection REL650 2.2 IEC
Technical manual