Alstom MiCOM P546 - 2.4 Channel aided schemes (Distance option only); 2.4.1 Distance scheme PUR - permissive underreach transfer trip (Distance option only); 2.4.2 Distance scheme POR - permissive overreach transfer trip (Distance option only); 2.4.3 Permissive overreach trip reinforcement (Distance option only)

P54x/EN AP/La4 Application Notes
(AP) 6-34 MiCOM P543, P544, P545 & P546
AP
2.4 Channel aided schemes (Distance option only)
The MiCOM P54x offers two sets of aided channel (“pilot”) schemes, which may be operated
in parallel.
Aided Scheme 1 - May be keyed by distance and/or DEF and/ or delta directional
comparison
Aided Scheme 2 - May be keyed by distance and/or DEF and/ or delta directional
comparison
When schemes share the same channel, the same generic scheme type will be applied - i.e.
ALL Permissive Overreach, or ALL Blocking.
2.4.1 Distance scheme PUR - permissive underrea
ch transfer trip (Distance option only)
This scheme is similar to that used in the LFZP Optimho, SHNB Micromho, LFZR, and
MiCOM P44x
(note 1)
distance relays. (Note 1: matches PUP Z2 mode in P441/442/444). It
allows an instantaneous Z2 trip on receipt of the signal from the remote end protection.
Send logic: Zone 1
Permissive trip logic: Zone 2 plus Channel Received
The “Dist dly” trip time setting should be set to Zero, for fast fault clearance.
2.4.2 Distance scheme POR - permissive overreach transfer trip (Distance option only)
This
scheme is similar to that used in the LFZP Optimho, SHNB Micromho, LFZR, and
MiCOM P44x
(note 2)
distance relays. (Note 2: matches POP Z2 mode in P441/442/444, and
POR2 scheme in LFZP/LFZR). Note that the POR scheme also uses the reverse looking
zone 4 of the relay as a reverse fault detector. This is used in the current reversal logic and
in the optional weak infeed echo feature.
Send logic: Zone 2
Permissive trip logic: Zone 2 plus Channel Received
The “Dist dly” trip time setting should be set to Zero, for fast fault clearance.
2.4.3 Permissive overreach trip reinforcement (Distance option only)
The
send logic in the POR scheme is done in such a way that for any trip command at the
local end, the relay sends a channel signal to the remote end(s) in order to maximize the
chances for the fault to be isolated at all ends.
Note: The send signal is generated by the ‘Any trip’ command and is sent on
both channels, Ch1 and Ch2, if more than one channel is in use. This
feature is termed permissive trip reinforcement, and is a deliberate
attempt to ensure that synchronous tripping occurs at all line ends.
2.4.4 Permissive overreach scheme weak inf
eed features (Distance option only)
Where weak infeed tripping is employed, a typical voltage setting is 70% of rated
phase-neutral voltage. Weak infeed tripping is time delayed according to the WI Trip Delay
value, usually set at 60 ms.