Alstom MiCOM P54 Series, Technical Manual, Page: 375 / 1024

Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546
(OP) 5-201
OP
If
Rst CB mon LO By
is set to
User Interface
the a further command appears in the the CB
CONTROL column of the menu,
CB mon LO reset
. This command can be used to reset the
lockout.
This logic is included in the Figure 113 and Figure 114 (CB Monitoring figure).
An auto-reclose lockout state of a circuit breaker will generate an auto-reclose circuit breaker
lockout alarm (
AR CBx lockout
) and DDB 306 or 328 is set, corresponding to CB1 or CB2
being locked out, as per the logic diagrams in AR Figure 57 and Figure 58.
The auto-reclose lockout conditions can be reset by various commands and settings options
found under the CB CONTROL column of the menu.
These settings and commands are described below:-
If
Res LO by CB IS
is set to
Enabled
, the circuit breaker lockout is reset if the circuit breaker
is manually closed successfully. For this the circuit breaker must remain closed long enough
so that it enters the “In Service” state. (See section 5.4,
Circuit Breaker In Service
and
Figure 109, Figure 110, Figure 111, Figure 112, Figure 113 and Figure 114.
If
Res LO by UI
is set to
Enabled
, the circuit breaker lockout can be reset by the user
interface commands
Reset CB1 LO
or
Reset CB2 LO
found in the CB CONTROL column of
the menu.
If
Res LO by NoAR
is set to
Enabled
, the circuit breaker lockout can be reset by temporarily
generating an “AR disabled” signal according to the logic described in section 5.6.6.2,
“Auto-reclose Enable” logic and AR Figure 5.
If
Res LO by ExtDDB
is set to
Enabled
, the circuit breaker lockout can be reset by
activation of the relevant input DDB
Rst CB1 Lockout
or
Rst CB2 Lockout
(DDB 446 /
1422) mapped in the PSL.
If
Res LO by TDelay
is set to
Enabled
, the circuit breaker lockout is automatically reset after
a user defined time delay as set in
LO Reset Time
setting.
The reset circuit breaker auto-reclose lockout logic is shown in AR Figure 57 and Figure 58
(logic diagram supplement).
5.7 Dual circuit breaker system voltage checks (P544/P546)
5.7.1 Dual circuit breaker system checks overview (P544/P546)
In some situations it is possible for both “bus” and “line” sides of a circuit breaker to be live
when the circuit breaker is open, for example at the ends of a feeder which has a power
source at each end. Therefore, when closing the circuit breaker, it is normally necessary to
check that the network conditions on both sides are suitable, before giving a CB Close
command. This applies to both manual circuit breaker closing and auto-reclosure. If a
circuit breaker is closed when the line and bus voltages are both live, with a large phase
angle, frequency or magnitude difference between them, the system could be subjected to
an unacceptable shock, resulting in loss of stability, and possible damage to connected
machines.
System checks involve monitoring the voltages on both sides of a circuit breaker, and, if both
sides are live, performing a synchronism check to determine whether the phase angle,
frequency and voltage magnitude differences between the voltage vectors, are within
permitted limits.