Alstom MiCOM P546 - 1.23.13 Delta blocking scheme (Distance option only)

Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546 (OP) 5-73
OP
DIR FWD
Z (T)
DIR FWD
Z (T)
R
R
DIR REV
DIR REV
G
H
CTX
CRX
Signalling
Equipment
CTX
CRX
Signalling
Equipment
&
DIR FWD
1
CB
Open
DIR FWD
1
CB
Open
&
&
1
Trip G
END G
t
0
Z
TZ(T)
&
1
Trip H
END H
t
0
Z
TZ(T)
DIR FWDDIR FWD
P1234ENa
P1019ENa
Figure 48 Delta directional comparison POR scheme (Distance option only)
1.23.13 Delta blocking scheme (Distance option only)
The si
gnaling channel is keyed from operation of the Delta Reverse elements of the relay. If
the remote relay has detected Delta Forward, then it will operate after the trip delay if no
block is received. Listed below are some of the main features/requirements for a permissive
overreaching scheme:
 BLOCKING schemes require only a simplex signaling channel.
 The blocking signal is transmitted over a healthy line, and so there are no problems
associated with power line carrier signaling equipment.
 Delta blocking schemes tend to be less secure than permissive schemes because failure
of the signaling channel could result in an unwanted tripping later. Therefore blocking
schemes are best supervised by use of a Channel out of Service indication.
 Fast tripping will occur at a strong source line end, for faults along the protected line
section, even if there is weak or zero infeed at the other end of the protected line.
 If a line terminal is open, fast tripping will still occur for faults along the whole of the
protected line length.