ABB RELION REB500 Technical Manual page 169

1MRK 505 406-UEN B
I
0
I-Setting
I-dir
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
• t
Wait
• Tx: send
• V-setting: reference voltage
Blocking directional comparison scheme
Providing the conditions for directional measurement are fulfilled, that is, the current higher
I-dir and the voltage higher than its enabling level V-setting , a protection function
than
transmits a blocking signal to the remote station immediately when a fault is detected in the
backward direction.
A protection function measuring a fault in the direction of the protected line trips at the end of
the adjustable waiting time
Bay protection functions REB500
Technical manual
Tx: I-Setting  MeasFwd  t
T: I-Setting  MeasFwd  t
TB: MeasBwd  t TransBlk
<Tx: MeasBwd  Rx>
TB: MeasBwd  t TransBlk
<Tx: MeasBwd  Rx>
V-Setting
Basic functions
Echo and "Transient blocking"
Echo
: basic time
: waiting time
I-dir = 0.7 I-Setting
tWait , providing a blocking signal is not received beforehand.
© Copyright 2019 ABB. All rights reserved
Basic
 Rx
Basic
I
asymm
U
0
18000061-IEC19000466-1-en.vsdx
Section 5
Bay protection functions
163