18000061-IEC19000466-1-en.vsdx
I
0
U
0
I-dir
I-Setting
V-Setting
I
asymm
Tx: I-Setting
MeasFwd
t
Basic
T: I-Setting
MeasFwd
t
Basic
Rx
TB: MeasBwd
t TransBlk
<Tx: MeasBwd
Rx>
TB: MeasBwd
t TransBlk
<Tx: MeasBwd
Rx>
Echo
Echo and “Transient blocking”
Basic functions
IEC19000466 V1 EN-US
Figure 62: Operation of a permissive directional comparison scheme
where:
•
<...>: optional function
•
Iasymm: asymmetrical currents under normal load conditions
•
I-dir: current enable for directional measurement (= 0.7 I-Setting)
•
I-Setting: current enabling level
•
MeasBwd: fault in backwards direction including Transient blocking
•
MeasBwd': fault in backwards direction
•
MeasFwd: fault in forwards direction
•
Rx: receive
•
T: trip
•
t TransBlk: blocking time
•
TB: transient blocking
•
t
Basic
: basic time
•
t
Wait
: waiting time
•
Tx: send
•
V-setting: reference voltage
Blocking directional comparison scheme
Providing the conditions for directional measurement are fulfilled, that is, the current higher
than
I-dir and the voltage higher than its enabling level V-setting, a protection function
transmits a blocking signal to the remote station immediately when a fault is detected in the
backward direction.
I-dir = 0.7 I-Setting
A protection function measuring a fault in the direction of the protected line trips at the end of
the adjustable waiting time
tWait, providing a blocking signal is not received beforehand.
1MRK 505 406-UEN B
Section 5
Bay protection functions
Bay protection functions REB500
163
Technical manual
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