• Only the trip part of the function can be used together with the blocking scheme. It is
not possible to use the echo function to send the echo signal to the remote line IED.
The echo signal would block the operation of the distance protection at the remote
line end and in this way prevents the correct operation of a complete protection
scheme.
• A separate direct intertrip channel must be arranged from remote end when a trip or
accelerated trip is given there. The intertrip receive signal is connect to input CRL.
• The WEI function shall be set to WEI=Echo&Trip. The WEI function block will then
give phase selection and trip the local breaker.
Avoid using WEI function at both line ends. It shall only be activated at the weak-end.
16.3.3 Setting guidelines
The parameters for the current reversal logic and the weak-end infeed logic (WEI)
function are set via the local HMI or PCM600.
Common base IED values for primary current (IBase), primary voltage (VBase) and
primary power (SBase) are set in a Global base values for settings function GBASVAL.
GlobalBaseSel: It is used to select a GBASVAL function for reference of base values.
16.3.3.1 Current reversal logic
Set CurrRev to Enabled to activate the function.
Set tDelayRev timer at the maximum reset time for the communication equipment that
gives the carrier receive (CRL) signal plus 30 ms. A minimum setting of 40 ms is
recommended, typical 60 ms.
A long tDelayRev setting increases security against unwanted tripping, but delay the fault
clearing in case of a fault developing from one line that evolves to the other one. The
probability of this type of fault is small. Therefore set tDelayRev with a good margin.
Set the pick-up delay tPickUpRev to <80% of the minimum sum of breaker operate time
+ communication delay time, but with a minimum of 20 ms.
16.3.3.2 Weak-end infeed logic
Set WEI to Echo, to activate the weak-end infeed function with only echo function.
Set WEI to Echo&Trip to obtain echo with trip.
Set tPickUpWEI to 10 ms, a short delay is recommended to avoid that spurious carrier
received signals will activate WEI and cause unwanted carrier send (ECHO) signals.
Section 16 1MRK 506 369-UUS -
Scheme communication
764 Line distance protection REL670 2.2 ANSI
Application manual
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