Manual Close; Circuit Breaker - Siemens 7SR224 Description & Operation

(1) Description of Operation 7SR224
4.2 M C
ANUAL LOSE
A Manual Close Command can be initiated in one of three ways: via a Close CB binary input, via the
data communication Channel(s) or from the relay CONTROL MODE menu. It causes an instantaneous
operation via 79MC Close CB binary output, over-riding any auto-reclose (AR) sequence in progress.
Repeated Manual Closes are avoided by checking for Positive edge triggers. Even if the Manual Close
input is constantly energised the relay will only attempt one close.
A Manual Close will initiate Line Check if enabled. If a fault appears on the line during the Close
Pulse or during the Reclaim Time with Line Check enabled, the relay will initiate a Trip and Lockout.
This prevents a CB being repeatedly closed onto a faulted line. Where Line Check = DELAYED then
instantaneous protection is inhibited until the reclaim time has elapsed.
Manual Close resets Lockout, if the conditions that set Lockout have reset i.e. there is no trip or
Lockout input present.
Manual Close cannot proceed if there is a Lockout input present.
With the Autoreclose function set to Disabled the Manual Close control is still active.
4.3 C B
IRCUIT REAKER
This menu includes relay settings applicable to both manual close (MC) and auto-reclose (AR)
functionality.
CB Controls Latched
CB controls for closing and tripping can be latched i.e. until confirmation that the action has been
completed i.e. binary input is edge triggered when latched.
Close CB Delay
The Close CB Delay is applicable to manual CB close commands received through a Close CB binary
input or via the Control Menu. Operation of the 79 MC Close CB binary output is delayed by the
Close CB Delay setting.
Close CB Pulse
The duration of the CB Close Pulse is settable to allow a range of CBs to be used. The Close pulse
will be terminated if any protection picks-up operates or a trip occurs. This is to prevent Close and Trip
Command pulses existing simultaneously. A 79 Close On Fault Output is given if a pick-up or trip
operates during the Close Pulse. This can be independently wired to Lockout.
'CB Failed To Open and CB Failed to Close features are used to confirm that a CB has not responded
correctly to each Trip and Close Command. If a CB fails to operate, the AR feature will go to lockout.
'79 CB Close Fail' is issued if the CB is not closed at the end of the close pulse, CB Close Pulse.
Reclaim Timer
The 'Reclaim time' will start each time a Close Pulse has timed out and the CB has closed.
Where a protection pickup is raised during the reclaim time the relay advances to the next part of the
reclose sequence.
The relay goes to the Lockout state if the CB is open at the end of the reclaim time or a protection
operates during the final reclaim time.
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