Manual Control; Circuit Breaker - Siemens 7SR21 Manual

4.8

Manual Control

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 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.
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.
4.9

Circuit Breaker

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 pick-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 DAR 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.
©2010 Siemens Protection Devices Limited
7SR21 & 7SR22 Argus Description of Operation
Chapter 1 Page 56 of 71