Siemens SIPROTEC 7SA522 Manual page 232

2 Functions
Interrogation of the
Circuit Breaker
Ready State
Processing the
Circuit Breaker
Auxiliary Contacts
232
tomatic reclosure is blocked for a manual-close-blocking time 7%/2&. 0&. If a trip
command is issued during this time, it can be assumed that a metallic short-circuit is
the cause (e.g. closed earth switch). Every trip command within this time is therefore
a final trip. With the user definable logic functions (CFC) further control functions can
be processed in the same way as a manual–close command.
A precondition for automatic reclosure following clearance of a short circuit is that the
circuit-breaker is ready for at least one TRIP-CLOSE-TRIP-cycle when the automatic
reclosure circuit is started (i.e. at the time of the first trip command). The readiness of
the circuit-breaker is signalled to the device through the binary input ´!&% 5HDG\µ
(FNo. 371). If no such signal is available, the circuit-breaker interrogation can be sup-
pressed (presetting) as automatic reclosure would otherwise not be possible at all.
In the event of a single cycle reclosure this interrogation is usually sufficient. Since, for
example, the air pressure or the spring tension for the circuit breaker mechanism
drops after the trip, no further interrogation should take place.
Especially when multiple reclosing attempts are programmed, it is recommended to
monitor the circuit breaker condition not only prior to the first but also before each fol-
lowing reclosing attempt. Reclosure will be blocked until the binary input indicates that
the circuit breaker is ready to complete another CLOSE-TRIP cycle.
The time needed by the circuit-breaker to regain the ready state can be monitored by
the 7SA522. This monitoring time &% 7,0( 287 starts as soon as the CB indicates
the not ready state. The dead time may be extended if the ready state is not indicated
when it expires. However, if the circuit breaker does not indicate its ready status for a
longer period than the monitoring time, reclosure is locked out dynamically (see also
"Reclose Block", above).
If the circuit-breaker auxiliary contacts are connected to the device, the reaction of the
circuit-breaker is also checked for plausibility.
In the case of single pole tripping this applies to each individual breaker poles. This
assumes that the auxiliary contacts are connected to the appropriate binary inputs for
each pole (´!&% 3ROH /µ, FNo. 366; ´!&% 3ROH /µ, FNo. 367; ´!&% 3ROH
/µ, FNo. 368).
If instead of the individual pole auxiliary contacts, the series connections of the nor-
mally open and normally closed contacts are used, the CB is assumed to have all
three poles open when the series connection of the normally closed contacts is closed
(binary input ´!&% S 2SHQµ, FNo.411). All 3 poles are assumed closed when the
series connection of the normally open contacts is closed (binary input ´!&% S
&ORVHGµ, FNo. 410). If neither of these conditions are present, it is assumed that the
circuit breaker has one pole open (even if this condition also theoretically applies to
the two-pole open state).
The device continuously checks the switching state of the circuit-breaker: As long as
the auxiliary contacts indicate that the CB is not closed (three-pole), the automatic re-
closure function cannot be started. This guarantees that a close command can only
be issued if the CB previously tripped (out of the closed state).
The valid dead time begins when the trip command disappears or signals taken from
the CB auxiliary contacts indicate that the CB (pole) has opened.
If the CB opens three-pole after a single-pole trip command, this is considered as a
three-pole tripping. If three-pole reclosure cycles are allowed, the dead time for three-
pole tripping is activated in the control mode with trip command (see margin
heading "Control Mode of the Automatic Reclosure")above; in control by pickup, the
pickup configuration of the starting protective function(s) is still decisive. If three-pole
7SA522 Manual
C53000-G1176-C155-3