ABB Relion 670 Series Technical Reference Manual page 826

Section 13
Scheme communication
820
BLOCK
WEIBLK1
200 ms
0
CRL
tPickUpWEI
0
WEI = Echo
ANSI09000032 V2 EN
Figure 406: Simplified logic diagram for weak-end infeed logic - Echo
With the WEI= Echo & Trip setting, the logic sends an echo according to the diagram
above. Further, it activates the TRWEI signal to trip the breaker if the echo conditions
are fulfilled and the neutral point voltage is above the set operate value for 3V0PU.
The voltage signal that is used to calculate the zero sequence voltage is set in the
ground fault function which is in operation.
BLOCK
WEIBLK1
0
200 ms
CRL
WEI = Echo&Trip
3V0PU
CBOPEN
ANSI09000020 V2 EN
Figure 407: Simplified logic diagram for weak-end infeed logic - Echo & Trip
The weak-end infeed echo sent to the strong line end has a maximum duration of 200
ms. When this time period has elapsed, the conditions that enable the echo signal to be
sent are set to zero for a time period of 50 ms. This avoids ringing action if the weak-
end echo is selected for both line ends.
&
0
50 ms
0 200 ms
AND
50 ms
100 ms
AND
1MRK505222-UUS C
AND
200 ms
0
ANSI09000032-2-en.vsd
AND
0
AND
ANSI09000020-2-en.vsd
Technical reference manual
ECHO
ECHO
TRWEI