ABB Relion 670 Series Applications Manual page 418

Section 15
Scheme communication
has to be sent through the primary fault. The unblocking function uses a guard signal CR_GUARD,
which must always be present, even when no CR signal is received. The absence of the CR_GUARD
signal during the security time is used as a CR signal. This also enables a permissive scheme to
operate when the line fault blocks the signal transmission. Set the
15.1.2.4 Intertrip scheme
In some power system applications, there is a need to trip the remote end breaker immediately
from local protections. This applies for instance when transformers or reactors are connected to
the system without circuit-breakers or for remote tripping following operation of breaker failure
protection.
In an intertrip scheme, the send signal is initiated by an underreaching zone or from an external
protection (transformer or reactor protection). At the remote end, the received signals initiate a
trip without any further protection criteria. To limit the risk for an unwanted trip due to the
spurious sending of signals, the timer
communication channel.
The general requirement for teleprotection equipment operating in intertripping applications is
that it should be very secure and very dependable, since both inadequate security and
dependability may cause unwanted operation. In some applications the equipment shall be able to
receive while transmitting, and commands may be transmitted over longer time period than for
other teleprotection systems.
15.1.3 Setting guidelines
The parameters for the scheme communication logic function are set via the local HMI or PCM600.
Configure the zones used for the CS send and for scheme communication tripping by using the
ACT configuration tool.
The recommended settings of
time for analogue channels according to IEC 60834-1. It is recommended to coordinate the
proposed settings with actual performance for the teleprotection equipment to get optimized
settings.
15.1.3.1 Blocking scheme
Operation
Set
Set
SchemeType
tCoord
Set
Set tSendMin
Unblock
Set
Set tSecurity
412
tCoord should be set to 10-30 ms dependant on the type of
tCoord timer are based on maximal recommended transmission
Enabled
=
Blocking
=
= 25 ms (10 ms + maximal transmission time)
= 0 s
Disabled
=
(Set to NoRestart if Unblocking scheme with no alarm for loss of guard is to
be used.
Restart if Unblocking scheme with alarm for loss of guard is to be used)
Set to
= 0.035 s
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1MRK 511 401-UUS F
tSecurity to 35 ms.
Bay control REC670
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