Intertrip Scheme - ABB RELION 670 SERIES Applications Manual

Section 16
Scheme communication
16.2.2.3
16.2.3
760
subjected to this type of interference, therefore, they must be properly shielded or
otherwise designed to provide an adequate communication signal during power system
faults. At the permissive overreaching scheme, the carrier send signal (CS) might be
issued in parallel both from an overreaching zone and an underreaching, independent
tripping zone. The CS signal from the overreaching zone must not be prolonged while the
CS signal from zone1 can be prolonged. To secure correct operations of current reversal
logic in case of parallel lines, when applied, the carrier send signal CS shall not be
prolonged. So set the tSendMin to zero in this case. There is no need to delay the trip at
receive of the carrier signal, so set the timer tCoord to zero.
Unblocking scheme
Unblocking scheme cannot be used at ZC1PPSCH (85) as a failure of the communication
channel cannot give any information about which phase/phases have a fault.

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 (CCRBRF, 50BF).
In intertrip scheme, the carrier send signal is initiated by an underreaching zone or from
an external protection (transformer or reactor protection). At remote end, the received
signals initiate a trip without any further protection criteria. To limit the risk for unwanted
trip due to spurious sending of signals, the timer tCoord should be set to 10-30 ms
dependant on type and security of the 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.
Setting guidelines
The parameters for the Phase segregated scheme communication logic for distance
protection function ZC1PPSCH (85) are set via the local HMI or PCM600.
Configure the zones used for the CS carrier send and for scheme communication tripping
by using the Application Configuration tool. The recommended settings of tCoord timer
are based on maximal recommended transmission time for analog 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.
1MRK 506 369-UUS -
Line distance protection REL670 2.2 ANSI
Application manual