P54x/EN AP/La4 Application Notes
(AP) 6-78
MiCOM P543, P544, P545 & P546
AP
For a single phase fault, CB1 will trip single phase and CB2 will trip three phase. When the
fault has been cleared, CB1 will reclose single phase without any system voltage checks
after the selected Single Phase AR dead time, then, after the follower time delay, CB2 will
reclose three phase, subject to a synchronism check between the line and Bus 2.
For a two phase or three phase fault, both circuit breakers will trip three phase. When the
fault has been cleared, CB1 will reclose three phase after the selected Three Phase AR
dead time, with either live bus/dead line or live bus/live line check synchronism between the
line and Bus 1. When CB1 has successfully reclosed, after the follower time delay, CB2 will
reclose three phase, subject to a synchronism check between the line and Bus 2.
For live line/live bus three phase reclosing of either circuit breaker, acceptable conditions are
typically:
The phase angle difference is not greater than 20 degrees;
The slip frequency is not greater than 0.05 Hz/s; and
The magnitudes of both the applied line voltage and “compensated” Bus voltage are
between 85% and 120% of nominal; and
The magnitude of the difference between the applied line voltage and the “compensated”
Bus voltage on either side of the circuit breaker is not greater than 10% of nominal.
It is assumed that reclosing at the remote line end will be either single phase with no system
voltage checks, or three phase with live bus/live line synchronism check.
5.2 Circuit breaker status
The ci
rcuit breaker open/closed status is signalled to the auto-reclose scheme by separate
type 52B auxiliary switch contacts on each circuit breaker pole (contact open when circuit
breaker phase is closed, contact closed when the circuit breaker pole is open).
5.3 Voltage inputs
The voltage i
nputs to the auto-reclose equipment are:
3 phase input (3P + N, magnitude 110 V Ph-Ph, 63.5 V Ph-N) from a line VT, connected
to the Line VT (main VT) input;
1 phase input (A-B, magnitude 110 V) from a Bus1 VT connected to the Bus1 VT
(CB1 CS VT), input;
1 phase input (A-B, magnitude 110 V) from a Bus2 VT connected to the Bus2 VT
(CB2 CS VT), input.
Under healthy system conditions each bus VT (check sync VT) input leads the A-phase to
Neutral Line VT input (main VT) by 30 degrees and has voltage magnitude of 110 V
(assumes settings in secondary values).
5.4 Application settings
Typical val
ues for the principal settings and user commands related to the auto-reclosing
and system voltage check functions are given below. They are presented in the order in
which they appear in the menu. The hexadecimal numbers in brackets/parentheses
represent the Courier cell location in the menu.
5.4.1 CB CONTROL menu:
In the
CB CONTROL column, the Autoreclose Mode command (07 0B) should be activated
by setting to In Service;
The data cell AR Status (07 0E) should display In Service.
The CB1 Status Input (07 11): should be set to 52B 1Pole;
The CB2 Status Input (07 80): should be set to 52B 1Pole.
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