As shown in Fig. 3-42, (p. 3-71), both additional conditions are valid
independently of each other, i.e. the following sequence is possible and requires
appropriate care in the application:
1.
The disconnection of an end is enabled by the additional condition:
MAIN: En. disc. end x EXT
2.
This enabling condition and the disconnection request will end, for
instance, with a fault in the triggering circuit.
3.
As soon as the measured current value in the disconnected end
drops below the 0.05 I
nom
threshold then the disconnection will be
cancelled.
The effective disconnection of an end is signaled by a state signal.
(041 149) MAIN: End a disconnected
(041 158) MAIN: End b disconnected
(041 159) MAIN: End c disconnected
(041 168) MAIN: End d disconnected
The ends are disconnected without delay, if the conditions above are fulfilled,
and this state is stored in fail-safe memory. The transfer of the actual connection
state, however, into non-volatile memory is carried out with an operate/reset
time-delay of approximately 0.5 s in order to prevent synchronicity problems
resulting from simultaneously switching on/off the auxiliary power supply and the
signal voltage at the binary signal input.
During the initialization phase after a failure of the auxiliary power supply, the
stored state is compared with the current state of the input functions. If a
discrepancy is detected (e.g. MAIN: En. disc. end x EXT AND NOT
MAIN: Disconnect End a EXT, or vice versa) the alarm message
SFMON: Disc. end x invalid is issued and the device remains blocked. The
blocking is cancelled as soon as the discrepancy ends, i.e. when the current state
of the binary input matches the logical state stored in the device. This is carried
out without checking the additional conditions mentioned above. Since the alarm
is being stored in the monitoring signal memory, it must be acknowledged by the
user.
P634 3 Operation
3-70 P634/EN M/R-42-A // P634‑311‑653
To Next Page
Loading...
