15.1.2.4 Intertrip scheme
M16866-71 v4
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 tCoor
d should be set to
10-30 ms dependant on the type of 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
IP15021-1 v1
M13869-4 v4
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 tCoord timer are based on maximal recommended
transmission 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
M13869-8 v5
Set
Operation Enabled
Set
SchemeType Blocking
Set
tCoord
25 ms (10 ms + maximal transmission time)
Set
tSendMin
0 s
Set
Unblock Disabled
(Set to
NoRestart
if Unblocking scheme with no alarm for loss of guard is to be
used.
Set to
Restart
if Unblocking scheme with alarm for loss of guard is to be used)
Set
tSecurity
0.035 s
Section 15 1MRK 511 401-UUS A
Scheme communication
472 Bay control REC670 2.2 ANSI
Application manual
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