Setting Guidelines - ABB REL650 Applications Manual

1MRK 506 334-UUS A
12.2.3
12.2.3.1
Application manual
circuit power of the source. To overcome these conditions, weak-end infeed (WEI) echo
logic is used. The fault current can also be initially too low due to the fault current
distribution. Here, the fault current increases when the breaker opens in the strong
terminal, and a sequential tripping is achieved. This requires a detection of the fault by an
independent tripping zone 1. To avoid sequential tripping as described, and when zone 1
is not available, weak-end infeed tripping logic is used.
The WEI function sends back (echoes) the received signal under the condition that no fault
has been detected on the weak-end by different fault detection elements (distance
protection in forward and reverse direction).
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 prevent 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.
Avoid using WEI function at both line ends. It shall only be activated at the weak-end.

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.
GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
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.
Section 12
Scheme communication
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