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 tCoord
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.
16.1.3 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.
16.1.3.1 Blocking scheme
M13869-8 v6
Set
Operation
=
On
Set
SchemeType
=
Blocking
Set
tCoord
= 25 ms (10 ms + maximal transmission time)
Set
tSendMin
= 0 s
Set
Unblock
=
Off
(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
16.1.3.2 Delta blocking scheme
GUID-F4359690-F433-46CB-A173-8C14559E3FCF v1
Set
Operation
=
On
Set
SchemeType
=
DeltaBlocking
Set
tCoord
= 0 s
Set
tSendMin
= 0 s
Table continues on next page
1MRK 506 369-UEN B Section 16
Scheme communication
Line distance protection REL670 2.2 IEC 707
Application manual
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