Alstom MiCOM P54 Series - 2.4.5 Distance scheme BLOCKING (Distance option only); 2.4.6 Permissive overreach schemes current reversal guard (Distance option only); 2.4.7 Blocking scheme current reversal guard (Distance option only); 2.4.8 Aided DEF ground fault scheme - permissive overreach (Distance option only)

Application Notes P54x/EN AP/La4
MiCOM P543, P544, P545 & P546
(AP) 6-35
AP
2.4.5 Distance scheme BLOCKING (Distance option only)
To allow time for a blocking signal to arrive, a short time delay on aided tripping, “Dist dly”,
must be used, as follows:
Recommended Dly setting = Max. Signaling channel operating time + 1 power frequency
cycle.
This scheme is similar to that used in the LFZP Optimho, SHNB Micromho, LFZR, and
MiCOM P44x
(note 3)
distance relays. (Note 3: matches BOP Z2 mode in P441/442/444).
Send logic: Reverse Zone 4
Trip logic: Zone 2, plus Channel NOT Received, delayed by Tp
Note: Two variants of a Blocking scheme are provided, Blocking 1 and
Blocking 2. Both schemes operate identically, except that the reversal
guard timer location in the logic changes. Blocking 2 may sometimes
allow faster unblocking when a fault evolves from external to internal,
and hence a faster trip.
2.4.6 Permissive overreach schemes current reversal guard (Distance option only)
The re
commended setting is:
tREVERSAL GUARD = Maximum signaling channel reset time + 35 ms.
2.4.7 Blocking scheme current reversal guard (Distance option only)
The re
commended setting is:
 Where Duplex signaling channels are used:
tREVERSAL GUARD = Maximum signaling channel operating time + 20 ms.
 Where Simplex signaling channels are used:
tREVERSAL GUARD = Maximum signaling channel operating time - minimum signaling
channel reset time + 20 ms.
2.4.8 Aided DEF ground fault scheme - permissive overreach (Distance option only)
This PO
R scheme is similar to that used in all other ALSTOM Grid relays.
Send logic: IN> Forward pickup
Permissive trip logic: IN> Forward plus Channel Received
Note: The Time Delay for a permissive scheme aided trip would normally be
set to zero.
2.4.9 Aided DEF ground fault scheme - blocking (Distance option only)
This
scheme is similar to that used in all other ALSTOM Grid relays.
Send logic: DEF Reverse
Trip logic: IN> Forward, plus Channel NOT Received, with a small set delay
To allow time for a blocking signal to arrive, a short time delay on aided tripping must be
used. The recommended Time Delay setting = max. Signaling channel operating time +
20 ms.