ABB RELION RET670, Applications Manual

Page: 837 / 1016

The WEI function can be extended to trip also the breaker in the weak side. The trip is
achieved when one or more phase voltages are low during an echo function.
Together with the blocking teleprotection scheme some limitations apply:
• 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 connected to input
CRL.
• The WEI function shall be set to OperationWEI = Echo&Trip . The WEI function
block will then give phase selection and trip the local breaker.
16.4.3 Setting guidelines
SEMOD156555-1 v2
SEMOD156562-5 v4
The parameters for the current reversal and weak-end infeed logic for phase segregated
communication function (ZC1WPSCH) are set via the local HMI or PCM600.
Common base IED values for primary current ( IBase ), primary voltage ( UBase ) and
primary power ( SBase ) are set in Global base values for settings function GBASVAL .
GlobalBaseSel : It is used to select a GBASVAL function for reference of base values.
Current reversal logic
Set OperCurrRev to On to activate the function.
Set tDelayRev timer at the maximum reset time for the communication equipment that
gives the carrier receive (CRLx) 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 to involve 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 .
Weak-end infeed logic
Set OperationWEI to Echo , to activate the weak-end infeed function with only echo
function.
Set OperationWEI to Echo&Trip to obtain echo with trip.
1MRK 504 163-UUS A
Section 16
Scheme communication
Transformer protection RET670 2.2 ANSI 831
Application manual