ABB REG316 4 Series Operating Instructions Manual page 129

REG 316*4 1MRB520049-Uen / Rev. F
I
R
I>
U j
&
ST
j
&
Receive
I
S
I>
U j
&
TR
j
&
I
T
I>
U j
&
RS
j
&
Fig. 3.5.7.3 Block diagram
Time allowed for a signal to be received
Where directional functions are configured in both line terminals,
each can send a signal from its "MeasBwd" output to the "Re-
ceive" input of the function at the opposite end of the line (e.g.
via a PLC channel) when it is measuring a fault in the reverse di-
rection. This signal prevents the respective directional overcur-
rent function from tripping, because the fault cannot be in the
zone between them. The functions therefore have to allow time,
i.e. the "wait time", for the signal from the opposite line terminal
to be received. If none is received within "tWait", the circuit-
breakers are tripped at both ends.
The time set for "Delay" acts in this kind of scheme as a backup
which does not rely on the communication channel. Thus when
the "Receive" input is being used, the setting for "Delay" must be
longer than the setting for "tWait":
"Delay" > "tWait".
Forwards meas. R
Reverse meas. R
Forwards meas. S
Reverse meas. S
Forwards meas. T
Reverse meas. T
td = "Delay"
t = "tWait"
ABB Switzerland Ltd
³ 1
t
&
³ 1
³ 1
Start R
Forwards meas.
AUS
³ 1
td
Start S
Reverse meas.
Start T
Start
3-91